t ColumtJia ®nibersiitp mtt)ECitpof^ebj|9orfe COLLEGE OF PHYSICIANS AND SURGEONS Reference Library Given by Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/manualofophthalmOOhogg R,l, j:, C^ckinfi duvnixi W.We^--/rp A MANUAL OF OPHTHALMOSCOPIC SURGERY ; A PRACTICAL TREATISE THE USE OP THE OPHTHALMOSCOPE DISEASES OF THE EYE; JABEZ HOGG, SENIOR ASSISTANT-SURGEON TO THE ROYAL 'WESTMINSTER OPHTHALMIC HOSPITAL; OPHTHALMIC-SnRGEON TO THE ROYAL MASONIC SCHOOLS ; LATE VICE-PUESIDENT OF THE MEDICAL SOCIETY OP LONDON ; FELLOW OF THE LINNEAN SOCIETY ; ETC. AnTHOR OP THE MICROSCOPE, ITS HISTORY, CONSTRUCTION, AND APPLICATIONS; ELEMENTS OP NATURAL PHILOSOPHY ; KTO. " These eyes, though clear To outward view of blemish or of spot. Bereft of light, their seeing have forgot.' THIRD EDITION, RErVVRITTEN AND ENLARGED. LONDON : JOHN CHURCHILL & SONS, NEW BURLINGTON STREET. MDCCCLXIII. Re \l>s-i- Co/I LONDON : PRINTED BY J. MALLETT, 59, WAKDOUK STREET. PRESIDENT, THE MOST NOBLE THE MARQUIS OF WESTMINSTER, K.G. VICE-PRESIDENTS, Duke of Cleveland, K.G. Duke of Rutland Earl of Shaftesbury Earl of Stratford Earl of Enniskillen Lord Dynevor Field Marshal Viscount Com- bermere, g.c.b. Sir Henry Holland, Bart. The Very Reverend the Dean of Hereford Major-General Wood Lewis Powell, Esq. AND THE COMMITTEE OF MANAGEMENT, OF THE ROYAL WESTMINSTER OPHTHALMIC HOSPITAL, In grateful recollection of early kindness and encouragement received from the Author's first connection with that invaluable Institution; AND TO HIS FRIEND AND COLLEAGUE, HENRY HANCOCK, ESQ. AS A TOKEN OF SINCERE RESPECT AND ESTEEM, THIS TREATISE ON OPHTHALMOSCOPIC SURGERY IS DEDICATED. EXPLANATION OF THE PLATES. PLATE 1. NO. 1. — The healthy fundus; the vessels of the retma, the optic nerve entrance, and the relative situation of the macula lutea. 2. — Retinitis ; the optic nerve entrance being reduced to a very small point by the chorio-capillary injection. 3. — Capillary apoplexy of the retina : the papilla optica in this case being completely covered over by the hsemorrhagic effusion. 4. — Detachment of the retina, extending to the optic nerve, which is seen considerably dilated, and the vessels very small. This dravdng was made a month after the accident occurred. PLATE 2. 5. — Atrophy of the optic nerve, with ansemia of retina, showing the saucer-like depression of the optic papilla. 6. — Syphilitic retinitis : the condition of the optic nerve and retina at the end of the second month, the sight being then very imperfect. 7. — Retinitis from albuminuria, with considerable disorganization of the retinal vessels. 8. — Softening of the retina : in this case cupping of the optic nerve was associated with the disease. PLATE 3. 9. — Glaucoma : considerable excavation of the optic nerve and irregularity of the vessels. 10. — Exudation between retina and choroid, believed to be fatty degeneration of the retina ; probably colloid disease of the choroid. U 290 EXPLANATION OF PLATES. 11. — Choroiditis pigmentosa and posterior staphyloma, \\'ith deposits of pigment over the macula lutea. 12. — Choroiditis pigmentosa; saucer-like depression of the optic nerve ; vessels atrophied and irregular. PLATE 4. 13. — Hj'peraemia of choroid, wnth capillary congestion. 14. — Choroiditis pigmentosa. In this case there was considerable capillary congestion, which, with the enormous quantities of pigment, covered the white spaces in the choroid coat, so that they were very faintly seen. 15. — ^The fundus of a myopic eye, sho^ving a crescentic depression at the outer periphery of the optic nerve ; the latter being pale and considerably dilated. 16. — Sclero-choroiditis pigmentosa: the vessels on the same side appear to have been either removed, or obscured by some exudation. V19. £ Cockxn^ chromo WWest imp P] '■^ J? fhckina dwimui WWcrt /' PI 4- E Cockuuj dxramxi WTt^^r xvj PREFACE. The confident opinion I entertained, when the first edition of this work af)peared, in 1857, of the value and importance of the ophthalmoscope as an unerring guide in the previously- obscure pathology of the eye, and the great popularity which I also anticipated it would achieve, have been fully realized by the results of the past five years' experience. That its introduction would form a new era in scientific investigation, I felt assured, from the advance of special knowledge when aided by proper methods of investigation, and the wide field afforded for industrious research, now that so ample an opportunity for making exact observation has been placed in the hands of the profession, and sufficient means afforded of establishing principles of ophthalmic pathology with the precision of some other branches of surgery. To forward this great object I considered a legitimate ambition, and to this feeling was due the first detailed notice of the new instrument that had appeared in England, con- tained in a paper read before the Medical Society of London, accompanied with cases and illustrations of its use derived from my own practice. To review the progressive steps that have been taken to elucidate, with the assistance of the oph- VI PREFACE. tlialmoscope, the real nature and seats of the most serious diseases of the eye, would require a special volume. It is more than probable, also, were I to attempt an account of successes during the unsettled phases of a transition state of knowledge, my observations would only lead to innumerable reclamations from several ardent and equally praiseworthy explorers in the same field : not to mention the questionable position any confident expression of opinion to-day might place me in, when to-morrow, perhaps, a more satisfactory advance would be made towards truth, on the basis of facts so clearly demonstrable in the ophthalmoscope, as to afford no opportunity for doubting or denial. But I must be allowed, in this introductory address, to en- large upon the increased responsibility of the profession, generally, to attain to a proper knowledge of the use and ad- vantages of this instrument. It has most certainly done something to rescue a special branch of surgery from the hands of mere empirics and ignorant pretenders to a know- ledge that, previous to its introduction, was unattainable ; and which was, perhaps, under the circumstances, sufficient ex- cuse for the conscientious practitioner who might be reluctant to interfere in cases where an error in practice was attended by such serious consequences as in diseases affecting the organ of vision. We all know what the stethoscope has done for affections of the chest, and the relying confidence in its assistance with which the general practitioner now explores, with interest and anxious concern, the condition of the lungs in the earliest stage of threatened disease ; and with much ad- PREFACE. VU vantage, individually, as well as to the great national question of annual mortality among the population, who can doubt ? And not less valuable, I firmly believe, will be the result of the introduction of the ophthalmoscope into general practice. It promises a vast diminution in the number of those cases where extinction of the sight, the most valuable and cheering of the senses, so often results from ignorance of the nature of the attack, or of the real seat of the disease. I may truly say that the most painful experience of a surgeon to a pubUc institution for eye disease, arises from the circumstances of his position informing him that many of the totally blind that come under his observation, might have escaped so great a misfortune, had circumstances been earlier favour- able for exploring the otherwise dark chamber of the eye, and reading off, as it were, a correct diagnosis, whilst op- portunity was afforded for proper measures of relief to have been adopted. It must, therefore, I think, be deemed morally imperative that every member of our profession should, for the future, make ophthalmic surgery a parti- cular object of study during his term of hospital attendance. And it is also worthy of consideration, how many different ways an accustomed and ready use of this little instrument will avail in the solution, when correspondingly assisted, of many otherwise obscurely situated complaints ; for there is no stronger corroborative evidence of the value of the oph- thalmoscope, as a reliable aid in diagnosis, than the adapta- tion of the same principles to instruments for the examination of the larynx and throat. Vlll PREFACE. As regards the arrangement of my subject matter, the text having been entirely re-written, the plan upon which I have proceeded requires a little explanation. In the first place, the instruments more particularly described are those which my own experience enables me with confidence to recommend. The simpler forms, I feel assured, are the best for the general practitioner, though for purposes of study and hospital practice the more elaborate and fixed kind is to be preferred, as admitting of steady and exact adjustment. To have attempted more in this direction v^ould have required a special volume upon the numerous ingenious ophthalmoscopes that have been submitted to the profession since Helmholtz's invaluable discovery. I may further add, as regards the principles and theory of vision involved in the examination, they are too exactly fixed, upon data almost mathematical, to admit of any variation or even novelty of remark in describing them. Nor did my purpose require any very laboured dis- quisition. Where necessary, I have quoted Helmholtz and Bonders, who have done so much for improving our know- ledge upon the accommodation of sight ; they have given us the most recent as well as the most rational views on the subject. For more scientific and enlarged details upon general optics in connection with the use of the ophthalmoscope. Dr. Rainy's treatise may be consulted with advantage. With respect to other authorities, I have not failed to make use of any inform- ation which I could confirm by my own observation ; for my aim on all occasions has been to establish principles of correct diagnosis in the hitherto obscure diseases of the internal eye. PREFACE. IX It will be observed, as regards cataract, I have some- what enlarged on the anatomical and physiological details of the several parts implicated in its progressive develop- ment. I felt this was required, by the numerous distinctive forms introduced in the pathology of this important class of eye disease ; and it cannot be doubted that it is essentially necessary to be as well acquainted with the normal conditions as with the diseased appearances of all the structures, as seen with the ophthalmoscope. In a great number of cases, changes may be discovered in progress sufficiently early — it is stated and believed by some physiologists — to prevent further advance. In the classification of eye diseases I have arranged them in the order of situation, and grouped them accordingly, instead of strictly following the great natural divisions of pathology, which are more suited to the generalization of disease, than to the particular application of the principles to a specially selected organ. It also admits of a less arbitrary restriction to technical terms in describing new appearances, upon the nature of which, circumstances as yet have not af- forded us full opportunity of deciding ; for by the aid of the ophthalmoscope we are enabled to diagnose slight internal changes which were before unrecognized. To illustrate the situation I am alluding to, I may refer to the symptoms describing retinitis, as laid down a few years ago in books and clinical lectures, and upon which no reliance can now be placed, as distinguishing it from several other diseases of in- ternal structures of the eye revealed to us in the ophthalmo- X PKEFACE. scope. In this transition state of knowledge, therefore, some latitude must be allowed in expression, and a little excuse made for what may appear indefinite and undecided. My readers may rest satisfied that it is always designed and prospective of future advance to be made. In the mean time, I trust there will be many explorers in the same field who will record their observations, as I have ventured to do ; and in this way a valuable collection of facts will result, that must hasten the elucidation of the scientific principles upon which a proper classification of eye disease can alone be based. At the same time, I may add, that I have chiefly recorded the results of my own experience, rather than relied upon the published cases of other observers, or as occurring in other institutions than the Eoyal Westminster Ophthalmic Hospi- tal, where I could watch the various details of treatment, the changing phases of progress, and ultimate conclusion, so as to possess definite data to test the soundness or otherwise of a previously formed diagnosis. Hospitals for special cases afi'ord unusual opportunities and facilities for the study of the particular diseases for which they are set apart, and a two- fold responsibility rests upon their medical officers. In the first place, they owe to the patients much of their time, and aU their care and skill ; and, in the next, their professional brethren very naturally look to have communicated to them whatever superior knowledge such exceptionable advantages have enabled them to acquire. A new era has, at all events, comumenced in ophthalmic surgery ; and if we reflect what has already been done since PREFACE. XI the introduction of the ophthalmoscope, we may well antici- pate still more splendid results. Let me enumerate the important points already attained : and, in view of which, it may well be asked, who would have ventured, a very few years ago, to have foretold the present state of knowledge ? Istly, we have, now, not the least difficulty in determining the existence or non-existence of cataract, formerly surrounded by so much doubt that sometimes no amount of professional skill or experience could satisfactorily solve. 2ndly, the approach of cataract may be observed in its earliest stage, and long before it is discoverable by the unassisted eye. 3rdly, it demonstrates the physical cause of muscee, and, conversely, when it is a symptom of disorder. 4thly, it has removed almost from ophthalmic nomenclature the indefinite term of amaurosis, where, as Walther observed, ♦' the patient and the physician were both blind," by revealing the depend- ance of many such cases on causes widely different, but easily enough perceived with the ophthalmoscope. 5thly, by disclosing retinal apoplexy, it prevents, in some cases, an injurious resort to mercurials ; and, on the other hand, by showing the presence of effusion of lymph on the deeper structures of the eye, it enables us to judge when such a treatment will prove advantageous and proper; and Gthly, its value is considerable, even in those cases of what may be called negative advantage, where, by showing the retina, already detached and disorganized, the surgeon might other- wise, without such knowledge, have been tempted to perform an utterly useless operation. XU PREFACE. In conclusion, I have only to observe, that although I have endeavoured to make the coloured illustrations of eye diseases more perfect and correct than in any former edition, yet, from the difficulty of finding a skilled artist, competent to read off appearances which are plain enough to the prac- tised eye of the surgeon (added to the great expense incurred by printing in colours, which precludes continued correc- tions), I have not by any means succeeded to the extent I could have desired. To render my little work more complete, I have added specimen pages of Jiiger's test-types, generally in use, and referred to in my cases. London, 1, Bedford Square, June, 1863. ERRATA. Page 3, line 6, for inter, read intra. 4, — 31,/o)* has, rec^ii have. 9, — 21, /or biconvex, read biconcaTe. 14, — 13, /or on, rcaJ in. 15, — 30, /or surgeon, r«ad patient. 15, — 3 4, /or the, read a. 15, — 35, afturWic. full point, read A speculum oculi, with or without a seconil lens, is employed in the usual manner by the surgeou. "29, foot note, for StoUing read Stellwag. 33, line 3, strike out the word spectral. 33, — 9, for spectrum, read light. 41, — 14, strike out the words, besides my own. 45, — 18, strike out the words, which arises. 57, — 3, /or ten, rearf two. 57, — 14, /or wholes, read whole. 60, — 18, strike out the words, other recti. 81, — 3,/or fall, r«ad falls. 81, — 5, strike out belongs, and insert, may be added. 81, — 27, /or instrumental, read spectacle. 81, — 28, /or accustom the eye, read bring the eyes. 84, — 26, /or glass, read glasses. 100, — 7, strike out the words, of the muscular fibres. 102, — 29, /or slightly, read pearly. 103, — 25,/or phenomena, read pulsation. 105, — 7, /or inter, read intra. 106, — 29, /or inter, read intra. 118, — 9, /or inter, read intra. 118, — 20, /or spread, read develope. 123, — "i^ifor artheromatos, read atheromatous. 139, — 20, /or optici, read opticus. 142, — 25,/or which is, read these are. 143, — 24, /or has, read have. 155, — 25,/or Albuminuria, read Albuminurica. 157, — 7, /or was, rearf were. 161, last line but one, /or these, read such. 164, line 3'i,for Anaguostakis, read Anagnostaki. 165, — 21,/or taken, read employed. 165, — 32, /or have given, read induced. 170, — 27,/or albuminuria retinitis, read retinitis albuminurica. 173, — 16, /or treaks, read striae. 179, — 31, /or Leucaemia, read Leucsemica. 203, last line,/or leucaemia, read leucaemica. 205, line 15, after observed, strike out, lying between them. 205, — 15, /or nerve, read nerves. 214, — 15, for tubercular, read tubercula. 215, — 5, for tubercular quadragemiui, read tubercula quadrigemina. 220, — 3, /or where, read when. 220, — 7, /or Marcotte's, read Mariotte's. 227, — 23, 28, and 32, /or Unilocular, read Monocular, 228, — 12, and 16, /or retina, read retinae. 229, — 16, 17, and 32, /or retina, read retinae. 230, — 18,/or retina, read retinae. -230, — 25,/or Farro, read Fauo. 331, — 9, /or stages, read stage. 232, — 5, /or fever, read fevers. 233, 5, /or diseased, read disordered ; for and is, read a disease. 239, — 34, and in subsequent pages, /or Philz, read Pilz.* 248, — 29, strike out the words, being then torn from its ciliary attachment. 249, — 24, /or M. Schwigger, read M. Schweigger. 273, foot note, read liildliche Darstellungen der Krankheiten des menschlichen Auges. ^276, — 2, after the semicolon, insert the words, these were. 277, — 17, /or at a, read to an. * Dr. Josef Pilz, "Lehrbuch der Augenheilkunde," Prager, 1859. A MANUAL OPniHALMOSCOPIC SURaERY. CHAPTER I. Altered Circumstances of the Modern Practice of Surgery connected with Eye Disease. Not the least important of the many triumphs of the Ophthalmoscope, is the increased attention to eye disease and ophthalmic surgery its introduction has excited among the profession generally. In fact, every one, who is honestly endeavouring to keep pace with the progress made in the sci- entific discoveries of the day, and who is at aU sensible of the value and utility of a direct means of examination in otherwise most obscure and doubtful cases, must confess that the little instrument of Helmholtz has originated not only a new method of inquiry, but must occasion a great revolution in all previous systems of ophthalmology. It is indeed curious to mark how men of estabUshed reputation, who, as a rule, are averse to no- velty, and unfriendly to innovation, have,' one after the other, successively surrendered their alleged objections, and become the strongest advocates for the use of the ophthalmoscope, when its revelations were found to be too obviously sound to admit of being disputed, wherever opinion was challenged to this simple but decisive test. £ 2 PRACTICAL ADVANTAGES With such unmistakable evidence of its great practical importance, and considering the extensive popularity it has achieved in comparatively a very short period, it is a matter of no Uttle satisfaction to me that the profession should in any way associate my name with its first introduction to theii- notice ; and, with the object of continuing a connection so honorable to myself, on the occasion of a third edition being called for of my little work on the Ophthalmoscope, published in 1856, I have determined to enlarge the scope of its original purpose, as chiefly illustrative of the theory of the ophthal- moscope, into the more ambitious purpose of supplying a rehable hand-book of its use, giving descriptions of the cha- racters and appearances of those diseases of the transparent media, and of the more important of the internal structural apparatus of the human eye, which that instrument now affords us so invaluable, and at the same time so convenient, a means of observing. In giving to the profession such a manual of Ophthal- moscopic Surgery, it is not intended to dwell upon elements presumed to be sufficiently well known ; nor, on the other hand, to follow up the extreme refinements of theoretical science connected with the subject, and which have some- times gone beyond what present experience could really warrant. But it must be obvious that the circumstances which have arisen with the occasion — the many novel and remarkable symptoms now for the first time observed — re- quire to be reduced into a system of properly defined diseases ; especially when a particular tecnology has been invented to describe these new appearances properly, and to find suitable language in which to record the wonderful progress made within the last few years in the pathology of the human eye. The task, moreover, is undertaken with an agreeable feeling that, in the general advance of human knowledge which late years have witnessed, ophthalmic surgery holds a position commensurable with the importance of the organ in its especial charge. It has ceased to be the suspicious do- main of the lingering empiricism of the last century ; for tlie OF THE OPHTHALMOSCOPE. o oculist now takes rank among the most scientific men in our profession. It is in this branch of practice that the interesting results of microscopic anatomy come to be beneficially uti- lized; and now that the ophthalmoscope gives the further com- mand of a direct means of examining the several media and inter-ocular structures of the eye, diagnosis in its diseases finds firm ground upon which to rest or base an opinion. The con- sequence is, that the uncertainty of symptomology, which formerly deterred so many conscientious surgeons of the first rank in the profession from interfering with diseased struc- ture or even disordered condition of the eye, has become in a great measure a mere bye-remark of congratulatory com- parison with the immeasurably improved circumstances under which, not only the ordinary general practitioner may con- fidently proceed with the care of the most serious cases, but which even enables an enquiring student of medicine to judge in a short time with the certainty of the more experienced practitioner of at least the character and extent of mischief within the orbit, wherever and whenever admitting of oph- thalmoscopic investigation. And if the profession have reason to rejoice that the res- ponsibilities of ophthalmic surgery, in a great measure, have ceased to be habitually referred to an empirical confidence, where success in treatment was more a matter of accident than the directed result of enlightened knowledge, how much more so must the general public share this feeling, with whom the eye, of all organs, is the most important and valuable. Examinations, not of form, as too often the case hitherto, now follows immediately upon injury ; and, nothing doubting, the practitioner in the humlilest sphere expects to find easily the situation and nature of the hurt. No valuable time is lost before proper measures of relief are adopted ; and the unfortunate sufierers are therefore no longer exposed to the additional danger arising from hesitation and delay — the too frequent causes of deplorable consequences in injuries to the delicate structure of the eye. Equally worthy of notice with this increased facility of B 2 4 INVENTION OF THE investigation, and the self-deiiendance it forms in the general practitioner, is the altered relation of some striking symp- toms in many important cases. Prior to the invention of the ophthalmoscope, a diagnosis frequently led to very- erroneous conclusions, by confounding together various affec- tions of the eye, differing widely in seat and proximate cause. For example : no distinction of appearance, or other resort of physical examination, could distinguish, in the large class of diseases called amaurosis, between functional disturbance in the apparatus of the eye, depending upon derangement in the general system, from other far more serious affections, depending upon actual disorganization in some impoi-tant -part. And if the value of the 6phthalmoscope be only esti- mated by the direct revelations it makes in such cases, there can be but one opinion on the subject. By directing treat- ment according to the special appearances now easily recog- nized, proper measures of rehef are adopted from the first ad- vent of the complaint, and all chances are avoided, or at least ought to be, of depleting where the opposite course should be taken, or vice versa ; the not unfrequent consequences of the former doubt and obscurity with which the whole subject was surrounded. Some hope to the patient, and at all events more promise of credit to the surgeon, are also to a considerable extent secured, with a convenient help to prognosis at hand, which enables us to determine what measure of rehef is to be expected, or whether the case is of such a nature as to authorize encoiu^agement being given that sight will be im- proved by any treatment whatever. The same observations upon the great practical use of the ophthalmoscope, and the a.ltered circumstances of modern practice which has accompanied its introduction, apply also to its convenience as a means of discriminating between the healthy and morbid conditions of the true optical ai^paratus, and satisfactorily ascertaining the state and degrees of trans- parency in all the important media, from the cornea to the fundus of the globe. True cataract is no longer liable to be confounded with an apparent or reflected opacity, asso- OniTHALMOSCOPE. '5 ciatcd with glaucoma; and diseases in tlio posterior tunics of the eye are readily distinguished, which were formerly too apt to be referred to opacity in the crystalline lens, and sometimes led to an entirely useless operation. In short, it may be correctly asserted that with the invention of the oph- thalmoscope commenced a new era in ophthalmic pathology. It has substituted exact knowledge concerning several dis- eases, differing vastly in character, origin, and seat, by con- verting indefinite and uncertain appearances into symptoms referrable to physical data that do not admit of misinter- pretation. Directed thus unerringly, diagnosis is enabled to complete its work, by pointing out the proper remedies or measures of relief required ; and it is only repeating a trite, axiom, to observe, that nothing is more assuring of a favor- able result than the possession of such knoAvledge of the real nature and facts of the case*. It is obvious, however, that a contrary charge lies against the old system of determining the character of eye disease ; and a feeling that it was so, had long been felt by the profession. Several ingenious minds, indeed, appear to have sought in the same direction as Helm- holtz for a solution of the difficulties experienced in forming a satisfactory judgment in cases that came under their care. The Progressive Character of tlie Invention of the Ophthalmoscope. The earliest observation, and which doubtless contains in its explanation the whole of the theory, and led to the * An accomplished and able physician (Dr. Mackenzie) has most truly observed, that " the great secret in treating eye cases— the secret without which every thing else must fail— is to know and discriminate the various states of disease to which the eye is subject. The successful removal of eye diseases depends almost entirely upon accurate diagnosis. Discover what the disease is, make out accurately the pathology of the case before us, make out the rationale of the symptoms, local and general, and if the case be cure- able, the cure is generally simple. Confound many different diseases, huddle them promiscuously together under a few general and perhaps unmeaning terms, and to a certainty we shall mistreat some of them." 6 LUMINOUS APPEARANCE discovery, of the ophtlialmoscope, was the mirror-like reflec- tion of light seen to emanate from the eyes of certain ani- mals*. Prevost demonstrated, in 1810, that this was pro- duced by a ray of light falHng upon the eye, and being reflected back, gave the eye that mirror-like appearance ; to see which perfectly, the animal must be in a darkened place, and the light made to fall upon it from without. This gene- ral observation of Prevost has only lately been revived and studied by Gumming, Helmholtz, Erlach, Briicke, and others, with relation to the human eye, and for the purposes of oph- thalmic surgery. In the early discussions upon the subject, it had been determined that the rays of Hght must be made to fall very obhquely into the eye, and that that of the ob- server should be placed on the same plane, or nearly parallel with the object eye. It was also remarked that the reflec- tion could be more readily observed in a darkened room, with a candle or other light placed about eight or ten feet before the eye upon which the experiment was being made. Our own countryman, Mr. Gumming, now more than sixteen years ago, in a paper " On the luminous Appearance of the Human Eye," contained in the 29th vol. of the Medico- Ghirurgical Transactions (1846), pointed out the existence of a reflection from the fundus of the eye, and distinctly recognizes the significancy of the discoveryf . He observes : " The establishment of the fact of a similar reflection from the healthy human eye to that from the eyes of animals, appears to me chiefly important in its adoption as a mode of examining the posterior part of the eye. The retina and * " There is nothing more easy than to see the vessels of the retina in a cat's eye without the ophthalmoscope. Having previously dilated the pupil by atropia solution, drop some water into the eye while the eye-lids are held apart, and cover the cornea with a thin plate of glass. The vessels of the retina can then be seen slightly magnified." — ^Wharton Jones. t It is due to Mr. Babbage to state that he appears to have been the first to suggest the use of a mirror with a small portion of silver removed from the centre. Here, however, he stopped short, without carrying his idea further ; or, at least, if he did, no record of the experiment is to be found. OF THE nUMAN EYE 7 choroid hitherto concealed in the living eye, and little oppor- tunity being afforded of examining their condition after life, in consequence of their diseases not terminating fatally, con- siderable uncertainty has hitherto attended the diseases ascribed to these structures ; but the existence of this lumi- nosity, its non-existence or abnormal appearance, may enable us to detect changes in these structures heretofore unknown, or satisfactorily to see those which we only suspected. If we dilate the pupil by atropia, we have the means afforded of seemg the condition of the retina and choroid in every case. The cases I have examined in this way have confirmed the general impression that the retina is not frequently the seat of change in amaurosis ; for out of several cases of amau- rosis, in which the mere opacity of the cornea, lens, and humours, allowed this mode of examination, I found but two in which the retina was so changed that the reflection was not seen. " The only circumstances necessary for observing the interior of the eye, are — first, that the eye must be placed at some distance from the source of light, the distance being greater as to the intensity; second, that the rays of light diffused around the patient, and sometimes aroimd the eye itself, be excluded; third, that the observer occupy a posi- tion as near as possible in a direct line between the source of light and the eye to be examined. " Let the person to be examined sit or stand eight or ten feet from a gas-light, looking a little to the side ; then ap- proach him in a direct line, and at once will be seen the reflection of the bottom of the eye. If solar Kght be admitted through a closed shutter into a dark room, the patient stand- ing five or six feet in front of the aperture, approach him as before indicated, when the luminosity of the interior of the eye will be immediately perceived. " On approaching within a few inches of the eye, the re- flection is not visible ; for before the eye of the observer can be brought within range of the reflected rays, the incidental rays of light are excluded. 8 CUMMINa, HELMHOLTZ, " In cases in which the lens had been removed, the re- flection was indistinct at a distance, but was rendered clearer by the aid of a double convex lens placed before the eye under examination; but at two or three feet distant, the reflection was as obvious as in cases in which the lens was present. " The brilliancy of the luminosity of the healthy eye ap- pears to be in proportion to the light colour of the pigment ; for, upon examining the eye of an Albino, by placing close to the eye a black card with an aperture a little larger than the pupil, the reflection was little brighter than that of a fair person examined side by side, but was of a more decided pink colour." Mr. Gumming then proceeds to inquire into the source of this reflection : u r£^Q retina in the living eye is a perfectly transparent medium in contact with the choroid or vitreous body. The transparency of the retina is, however, no proof that it does not itself reflect many of the rays of light that impinge upon it, although the greater proportion are transmitted: the transparency of a structure being quite consistent with con- siderable reflection, but not with absorption of the rays of light ; and thus reflection would be rendered more obvious by the position of the choroid." It may be gathered from these remarks that the first prac- tical suggestions for the present mode of examining the internal eye, and investigating its diseases, were made by Gumming. In the objects stated with which he commenced his experiments, in the means he used for examining eyes, and the precautions necessary to obtain the desired efl"ect, we find all the fundamental principles engaged in the prac- tice, or which enter into the theory, of the ophthalmoscope. All that was required to complete his discovery and produce the present convenient instrument, was the adoption of the mirror, and the use of reflected instead of transmitted light. Helmholtz was the first to perceive the advantages to be thus derived ; and it is usual to associate with his name the honor AND BRXJCKE'S INVESTIGATIONS. 9 of the invention of the ophthalmoscope. To him is certainly due the credit of having been the first to employ a reflecting apparatus as a means of exploring the eye ; but in the form which he proposed there were obstacles to its general use that made it less available even than the more direct method of Gumming, except in the hands of expert and practised operators. It is even a question now, with many distin- guished oculists, whether some diseases seated far forward in the eye are not more clearly discernible and distinguished by the condensed, transmitted light of a biconvex lens, rather than by reflected light thrown artificially into the eye. No notice seems to have been taken of Mr. Cumming's ex- periments in this country ; but it appears that, during the following year, his paper fell under the eyes of M. Briicke, Professor of Physiology at the University of Vienna; and here, with great opportunities for studying these phenomena, and at the same time being associated with the inventive ge- nius of Helmholtz, the first form of the ophthalmoscope was eventually given to the profession. This consisted of a small metallic box, the interior of which was blackened, to prevent the diffusion of light. At one extremity, in close juxta-posi- tion, were placed three parallel plates of glass, inclined at an angle of about 56° : at the other end was a circular hole, or short tube, in which was fixed a biconvex lens, through which the observer looked into the eye of the patient sitting oiDposite. Into this the light of a lamp was received and reflected from the surface of the glass, part of which, on its return, passed through the plates and reached the eye of the observer ; who was thus enabled to obtain an inverted and magnified image of the fundus ocuU. It was soon found, however, that the image was too faint and indistinct to be of any gTcat practical use ; for the glass plates interfered with a free transmission of light, and thus the greater part of the few rays returning in the visual axis were lost. To this, in a great measure, is to be attributed the abandonment of Helmholtz's form of the ophthalmoscope ; for although his own suggestion, of intro- ducing another biconvex lens between the glass plates and 10 COCCITJS, MEYERSTEIN, the patient's eye, remedied to some extent the indistinctness of the image, still it was only available in examinations of the crystalline lens and humours, the light it afibrded being in- sufficient to admit of the deeper parts of the eye being clearly seen. Although Briicke's investigations at the University of Vienna, wliich led to the invention of the ophthalmoscope by Helmholtz, were instigated in the first place by a perusal of Cumming's paper, the claims of our countryman to be considered an original observer have been signally overlooked on the Continent ; and Desmarres gives all credit, without reserve, to Helmholtz, who, according to his statement, in- vented the ophthalmoscope in 1851. It is not difficult, how- ever, nor need it be made an invidious task, to accord, each one his due, to all the distinguished labourers in that course of progressive improvements which ultimately produced the pre- sent efficient, though I must not presume to say perfect, form of th& instrument. Coccius, it appears, first substituted a reflecting mirror for the plates of glass ; and it is upon this principle that all the ophthalmoscopes now in use are based. The proposition of another German ocuhst, Meyerstein, to replace both plates and mirrors by the use of a perforated prism, never attained to any degree of favour. In using it as a hand instrument, the length of the sight hole, or prolonged canal rather, through the substance of the glass, rendered its manage- ment, in obtaining the axis of mutual vision, an almost in- surmountable difficulty. Zehender's ophthalmoscope differs from that of Coccius only in substituting a perforated plane metallic mirror, in- stead of the concave silvered glass one ; but in practice it is found that, if it possesses one advantage of more perfect illu- mination at short distances from the eye, in the dii-ect method of examination, still Coccius's is to be preferred, as involving fewer considerations of careful adjustment, and less danger of an imperfectly reflecting surface, from the deteriorating action of the atmosphere, accidental scratches, &c. AND ZEIIENDER'S OPHTHALMOSCOPE. 11 The improvement wliicli, about the same time, Jager l^roposed, by fixing two lens of dijScrent focal lengths upon the projecting arm of a frame supporting the mirror, was an advance towards the larger and more perfect ophthalmo- scope of Liebreich, which soon followed, with all its conve- nient appUances, to correct the unsteadiness of the surgeon's hands, while holding the lens and mirror, and to secure the permanency of the patient's head in one plane and position, so necessary to obtain a perfect view of the fundus of an illuminated eye. Before proceeding, however, in a separate section, to describe this latter instrument in detail, as ex- hibiting the best combination of all the several aids in oph- thalmoscopic examinations, I must be allowed to make the general acknowledgment, that it is to Germany the credit is chiefly due of most of those inventions which have raised the study of diseases of the eye to its present very advanced and most satisfactory position. The Construction of the Ophthalmoscope. As may be collected from my previous remarks, a great number of ophthalmoscopes, of different forms, have been invented; but all are based upon the same principle, the essential requirements being a mirror or reflecting surface, and a lens. The object is, that the eye of the observer shall be placed in such circumstances as to receive the greatest number of rays returning from the illuminated retina of the patient under examination. " Every one knows the difficulty of seeing the interior of a chamber lighted by a small aper- ture when it is looked at from the outside, even though the chamber may appear well lighted to those within. Thus, if we attempt to look through the window of a room ft'om the other side of the street, we find it difficult to see the opposite wall of the room ; because each point on its surface, instead of having light falling upon it from every direction, as it would have if it were in the open air, is illuminated by a cone 12 PRINCIPLES OF CONSTRUCTION. or pyramid of light, the apex of which coincides with the point in question, while its angle is determined hy the size of the window and the depth of the room." * * * * "If the ohserver's head is much larger than the aperture through which the light falls, he will find it difiicult to place himself at any convenient distance nearer the aperture than the source of Hght itself is, so that light from the point in the chamber he mshes to see may enter his eye, without shutting off, by the intervention of his head, all the light from the inte- rior of the chamber ; while, if he places the source of light between himself and the aperture, his o^wti eye ^^'ill be dazzled." * This familiar illustration graphically describes the chief obstacle which renders it impossible, under ordinary circum- stances, to see objects within the chamber of the living eye. Helmholtz, in his first researches upon the subject, demon- strated that the blackness observed in the eye of another is the absolute result of no available light in interchangeably reflected rays being received by either indindual, and that, unless some special means were taken, it is not possible for one person to place his eye so as to receive vrithin its range of vision the rays returning from the retina of another's ; for in attempting to do so he intercepts all the rays of light, which must in the fii'st place fall upon the fundus of the eye observed, before they are reflected back to his ovna.. When, however, the eye of the observer can be so placed in the axis of the cone or bundle of rays of light emerging from the pupil of the eye observed, without interposing any obstacle to the free passage of the light passing into the latter, a good view of the fundus of the eye is capable of being obtained. The effect of the operation is greatly increased, if the observer's eye is protected by a shade from the direct light of the lamp, or other artificial means of illumination circumstances re- quire ; and if, at the same time, he can change the dii*ection of the reflected rays, so that they be made to meet at the proper focus on the observer's retina. * Rainy's ' Theory of the Ophthalmoscope,' page 4. LTEBREICIl'S OPIITDALMOSrOPE. 13 These required conditions for the successful explora- tion of the chamber, media, and fundus of the eye, are sup- plied by most forms of the ophthalmoscope. A description of one Avill therefore be quite sufficient for the object I have in view, of giving a popular (in a sense restricted to the pro- fession) and, I trust, a useful hand-book of the employment of this most important and valuable instrument. I have selected Licbrcich's large ophthalmoscope, inasmuch as it is generally allowed to be the most available for careful research, and most convenient for the study of ophthalmic patholog3% as revealed to us by this new method of investigation. When once properly adjusted, even the non-professional artist finds little difficulty in detecting the minutest traces of altered structure or condition in the parts affected, to which his attention has been directed. Liebreich's large ophthalmoscope may be described as consisting of a telescopic tube, or rather two tubes, one sliding within the other, and admitting of extension for local ad- justment by a rack and pinion. A perforated mirror is placed in position at the observer's end of the tube, suspended ver- tically on Kttle projecting arms, which allow of its being easily moved in the direction most suitable to receive the rays of light from a lamp, and for which purpose a portion of the tube is also cut away. Behind the Kttle perforation in the mirror, is placed a convex lens of low power. The end of the tube next the patient is fitted with a double con- vex lens. The instrument proper is encircled by a strong ring of metal, which slides on an upright rod or stand, so that it can be raised or lowered according to circumstances. Above and below the tube itself, are two other sliding arms, fitted with pads, one to receive the chin of the patient, the other to support the forehead, so that the completest rest is assured during examination. To fix accurately the posi- tion of the eye itself, a small brass ball at the extremity of a pointed rod is attached to the tube, and can be placed in any direction. The whole instrument is screwed to the table or desk, by a strong c^-anip and screw. 14 SIMPLE FORMS. For demonstrating to students, and for drawing, Liebreich's instrument is the most useful I know of: any number of persons, indeed, can observe the appearances. Although I have described this larger instrument of Lie- breich's as being almost perfect for purposes of study and clinical examination, I shall not introduce sjoecial illustra- tions or diagrams of the optical problem involved in its opera- tion ; these I reserve for the smaller and much simpler form of ophthalmoscope, and which is sufficient for all ordi- nary purposes. The one I make use of myself is a small circular mirror ; indeed, nothing more than the silvered spe- culum used with the compound microscope, having a hole bored in the centre, and mounted on a little frame of tortoise- shell. This simple form of instrument has proved by far the most convenient ; as it is held easily in the hand, and can be brought to any position, or turned in any direction, as ne- cessity may dictate. The mode of using this little instru- ment is shown in the annexed diagram : Fig. 1. In using this ophthalmoscope, and which is generally known as that of M. Anagnostaki's, from a Greek physician, who first introduced it into general practice^, a lamp js placed in such a position, behind and to the side of the pa- * It is stated that Anagnostaki was a pupil of Reute's, ia Vienna, at the time of Von Erlach's and Helmholtz's researches, and thus obtained a knowledge of this particular form of ophthalmoscope. ailANDMONT'S OPHTHALMOSCOPE. 15 tient's head, as to throw its light upon the mirror A B. The converging rays proceeding from the concave surface of the mirror are intercepted at a short distance from the eye of the patient, and made to pass through a biconvex lens (C), which so considerably increases the convergence as to bring them sooner to a focus in front of the retina, where dispersing after intersection, the whole of that membrane is illuminated, and what may be termed the camera or chamber of the eye is filled with light. It is necessary, not only for the uni- formity of the illumination, that the focus be made to fall relatively before or behind the retina, but also to obviate some irregularities of appearance to which I shall refer hereafter, and which arise from adverse circumstances, that cannot be avoided in the construction and use of the instru- ment. It only requires to be observed here, that the mirror (A) is perforated in the centre with a small aperture or sight hole, about one sixth of an inch in diameter, through which, in the illustration, the observer's eye D is supposed to be looking ; while the other eye is employed in directing the con- vex lens, and keeping the patient's eye in the visual axis. The mirror, it should be noted, is here represented much too large. Another ophthalmoscope, which is so far properly de- scribed as holding a middle place between the fixed and the hand forms of the instrument, is a recent invention of M. de Grandmout of Paris, and has been pronounced by some emi- nent French oculists to be a great success, possessing eveiy desirable requirement. By means of an elastic band, a kind of skeleton spectacle frame is securely fastened upon the head of the surgeon. Between the orbital rings is a metallic plate, adapted to the form of, and resting upon, the bridge of the nose. From this projects a grooved bar, also of metal, and several inches long, on which slides a double -jointed arm, supporting the lens, that may thus be readily adjusted to any required distance. The advantages of this form of the ophthalmoscope are stated by the inventor to be — firstly : that it supplies practitioners with a readier means of accu- 16 grandmont's ophthalmoscope. rately observing the fundus oculi ; all other kinds requiring much practice, and trying the powers of endurance both of the observed and the observer. Secondly : as a consequence of the quickness with which observations are made, the pa- tient escapes the evils to be feared from injury to an already over- sensitive retina, likely to arise from long-continued ex- aminations. At the same time, many persons in succession may observe the appearances without disturbing the optical arrangement of the instrument. Thirdly : the right hand of the sui'geon is left free to fix or direct the head of the patient in any required position — an advantage illustrated in seeing the vessels on the surface of the retina, when it is necessary frequently to alter the position of the head, so as to bring the vessels and papilla optica within the field of vision. Fourthly : by holding the instrument in the hand, the image obtained is subject to some considerable change of appear- ance, owing to the unavoidable shaking of the hand that holds the lens — a defect remedied by the lens being fixed in this instrument. Lastly : the rod to which the instrument is attached admits of the employment of a lens with a long focal range, which magnifies the image and affords every opportunity of examining the minutest details. I have been induced thus to particularize the alleged ad- vantages possessed by this invention of M. de Grandmont, from the circumstance of its use being strongly recommended : but after many earnest endeavours to realize the desu-able objects enumerated, I must say that I have been somewhat disappointed, and cannot bear testimony in favour of its superiority over that of others. The idea that it represents a useful mean, as correcting the deficiencies between the two forms of the fixed and hand instruments, cannot be sustained for a moment ; at least, those who entertain such an opinion must difter considerably from me in their estimate of the great practical purposes served by retaining the two forms and using them as circumstances may require. With the convenient hand mirror and pocket lens, a very moderate amount of practice enables us to obtain an accurate diagnosis meyerstein's ophthalmoscope. 17 ill most cases. The lesser ophthalmoscope possesses a readi- ness of application that will always recommend it, in prefer- ence to any other which involves a large amount of careful, if not considerable, adjustment, before it can be effectively used. At the same time, the hand mirror does not, nor ought it, exclude the fixed or larger kind of instrument, for the close and attentive observation of the various forms and phases of eye disease. To depend upon any thing less efficient, where- ever doubt or obscurity exists, is sacrificing too much to convenience ; and it is on such grounds that I object to any proposed mean, however happy, between the ready aid afforded by the lesser ophthalmoscope (which is quite suffi- cient in the great majority of cases, but far from accomplish- ing all that is sometimes required), and that which is only to be obtained by the employment of the more perfect, al- though more complicated, fixed instrument. My chief objection, however, to M. de Grandmont's oph- thalmoscope, is the constant mental effort necessary to sustain that first principle in all examinations of the kind — the keep- ing the eyes of the observer and the observed in one axis or line of sight. Owing to the greatly enlarged arc that the further extremity of the projecting arm necessarily describes, on the least movement of the end resting on the bridge of the nose, it demands very considerable practice and dexterity to deter- mine the degree of fineness, and no more, in the movements of the head, which is constantly required to enable us to look steadily through the limited area of the patient's pupil. This, I think, will prove an insurmountable obstacle to the general use of the otherwise ingenious contrivance of M. de Grandmont — even if there were not many cases in which the patient's eyes are so unsteady that a lens fixed in any way cannot be used at all. It remains for me to notice a slightly modified form of Meyerstein's ophthalmoscope, which I am in the habit of using. Interposed between the flame of a common paraffin lamp (e, j%. 2), and the instrument a, a, sliding on the upright rod h, and clampt to the edge of a table c, is a screen of black- c 18 PIXED OPHTHALMOSCOPE. ened cardboard, g, made sufficiently long to extend either way beyond the heads of the surgeon and of the patient under observation. A circular hole in this shade con- ducts the light to a plain mirror, which reflects it at right angles along the main sight tube to the fundus of the eye. A little projecting wooden support, fZ, for the chin of the pa- tient is also clampt to the table, and completes the apparatus. When necessary, in long examinations, a bar of wood to rest Fig. 2. Fig 2.— Fixed ophthalmoscope, a a, the telescopic tube, and square box containing lenses and mirror, firmly secured to the upright rod, b, and clampt to the table, c. A wooden support, d, is also clampt to the table, for the pur- pose of supporting and steadying the patient's head. The mirror being illu- minated by the lamp, e, while the screens, /and ^, shut out the light from the face of both patient and surgeon. BINOCULAR OPHTHALMOSCOPE. 19 the forehead against can be attached to the crutch under the chin. The hand screen,/, effectively shuts off all light from the patient's face. With this instrument, I find little or no difficulty in arranging and adjusting all things at pleasure, and so far can command the best opportunity, circumstances admit of, for becoming well acquainted with the disease under investigation. If not altogether perfect, and leaving some- thing yet for future ingenuity to improve upon, still I have abundant cause to be satisfied with the valuable assistance I am continually deriving from this simple apparatus. It also affords a ready means of clinical demonstration, as well as facility of obtaining the aid of an artist to produce illustra- tive di'awings. I have merely a few remarks further to add upon the binocular ophthalmoscope lately introduced, the invention of M. Nachet. Its chief peculiarity is, that the mirror is placed in the median line between the visual axes of the two eyes, and moves with a hinge-like motion upon a horizontal axis. The lamp is also placed in the median line, behind and immediately above the head of the patient, into whose eye the reflected light is thrown by adjusting the mirror to the necessary angle of reflection. Projecting frames, placed on both sides of the instrument, contain two small prisms in each, and are intended for the accommodation of myopic and presbyopic observers. To facilitate the necessary change in position, these prisms are set in sliding grooves. With normal sight, the observation is made by looking through the prisms, much as we do in the well-known stereoscope. In this mode of illuminating the eye, any inconvenience arising from the unreflected spot which marks the sight aperture in the ordi- nary ophthalmoscope is entirely obviated ; and sonie advan- tage is also gained by the position of the lamp. Experienced observers, however, will, I think, continue to prefer the much more portable form so generally employed, all the deficiencies of which may be corrected by a little patience and tact. c 2 20 CHAPTER II. OPTICAL PRINCIPLES INVOLVED IN THE USE OF THE OPHTUALMOSCOPE. The Nature of Light. Light is an emanation from the snn, becoming less in- tense as it is diffused, and wliich, by falling on other bodies, and being reflected thence to the eye, renders them visible. Recent scientific investigations go far to prove that the sun is an enormous mass, or rather nucleus of matter, heated to an inconceivable degree, and luminous in proportion, "with an atmosphere of flame sm-rounding it. To this globe of ours it is the chief source of heat and light, propagated by means of an ether which fiUs all space, and of the existence of which we become cognizant by its retarding the speed of comets. Both heat and light consist in certain movements or vibrations in the atoms of this luminous mass ; and when these vibrations ai*e communicated to the suiTOunding ether, they ai'e said to radiate; when they are interrupted and arrested by any other body, they are said to be ahsorhed. Immense masses of solid matter are readily penetrated by Hght. Thick plates of sohd rock-crystal, mountains of ice, &c. are instantly pervaded by a beam of light. Never- theless, some solid and gaseous bodies possess the curious property of separating the heat from the light ray. The transparent soHd body, rock-salt, does this ; likewise some gases, as oxygen and hydrogen. These, as well as a few others, also absorb radiant heat of different qualities and in different degrees — a fact of some interest, inasmuch as NATURE OF LIGHT. 21 Professor Tyndall proved that the eye possesses a wonderful provision for the exclusion of heat rays. He found, beyond the visible si)ectrum in both directions, rays which excite no impression of light. Those at the red end excite heat, but no light ; and the reason why they fail to excite light in the eye, is, jjrobaljly, that they are never permitted to reach the retina. To show this experimentally, a thermo-electric pile was placed near to the red end of the spectrum, but still outside of it ; the needle of a large galvanometer connected with the pile was deflected and came to rest in a position about 45° fi'om zero. The transparent vitreous humour of the eye of an ox was now placed in the path of the rays, the light of the spectrum was not perceptibly diminished, but the needle of the galvanometer fell to zero ; thus proving that the obscure rays of the spectrum, to which the galvanometric deflection was due, were wholly absorbed by the humours of the eye. The quantity of heat is measured by the amount of the galvanometric deflection which it produces ; its power of l^assing through media may be taken as a test of quality. Fig. 3. This experiment may be varied in the following manner : A B, jig. 3, represents a blackened screen, with a central aperture in it of about half an inch in diameter ; I, a heated ball of iron ; and D, a thermo-pile, having connecting wires in communication with the galvanometer, and which shows a considerable deflection. If an ox-eye be now acctrrately adjusted to fill up the aperture C, all the heat rays are im- mediately stopped, and the galvanometer returns to zero. 22 OPTICS. Particular kinds of light are absorbed or transmitted much more readily by some substances than they are by others. The apj^arent colour, as well as intensity of the light reflected from or transmitted through different bodies, depends very much upon contrast ; and certain substances have a property termed diplochromatism, in virtue of which they reflect light of one colour, and transmit Ught of another colour. The crystalline lens of a glaucomatous eye, which appears to be greenish by reflected light, and yellowish brown by ordinary transmitted light, day-hght*, is an example of this. However, all bodies that are visible reflect light ; in other words, cause a ray to turn back or rebound from their sur- face when it impinges ujjon them. It is by the entrance into the eye of these reflected rays that an object is seen. A per- fectly transparent object would be invisible. Many trans- parent bodies, as glass, water, and the media of the eye, reflect a part of the light that falls on Ihem. Water also absorbs a part. Any thing that entirely absorbs light is opaque or black. Any thing that completely reflects all the light, is white or destitute of coloiu'. Colours are produced by a breaking up of the ray of white light, of which a body recognized as coloured, reflects a part, and absorbs another part. With whatever obliquity light strikes on a plane sur- face, with the same obliquity is it reflected from it in another direction. Most bodies have rough sm-faces, made of an immense number of planes. These scatter light by sending back the rays, so that they cross in all directions. Smooth or poKshed bodies have only one surface. This re- flects light in one direction, so as to afford to the eye an image of any object before them. Of such surfaces, of metal or glass, are formed miiTOrs or specula. * Dr. Mackenzie — Ou the Diseases of the Eye, 4th edition, page 805. DIOPTRICS. 23 Dioptric Principles involved in Ophthahwscopic Examinations. It is unnecessary to enter here more fully into the nature and properties of light. I therefore proceed at once to direct attention to some general laws which regulate the passage of light from one point to another, through bodies of diverse forms and through media of different densities ; as these are all involved in the theory of the ophthalmoscope, and without a knowledge of which, the use of that instrument becomes merely empirical, if indeed it may not be said to be unrea- sonable. Eays of light, when once they have passed into a medium of uniform density, proceed in straight lines. If, however, they are interrupted in their course, and made to pass through another substance differing in density — as, for ex- ample, from air to water — the lines of original direction are altered at the surface of the new medium. To cite a well- knovm example : — ^Place a shilling in a basin, and retire to such a distance that the shilling is lost sight of. If an assist- ant now iDour water into the basin, the shilKng will again appear witliin range of vision. This is the effect of the law of refraction. Rays of light, on passing from the water to the air, are bent at the surface, so as to clear the edge of the basin by an angle of refraction, and made to fall obliquely into the eye of the observer. In this case, the rays of light pass from a medium, water, which has greater re- fractive powers than the air into which they pass, and accord- ingly it will be found- that they are deflected from the per- pendicular; or, as it is otherwise expressed, the angle of refraction is greater than the angle of incidence. On the contrary, the reciprocating rays of light returning from the eye to the object point are subject to an opposite effect, in passing from the aii', which has less refracting powers than that of the aqueous fluid; they are deflected towards the 24 DIOPTRICS. perpendicular ; or, in other words, the angle of incidence is greater than the angle of refraction*. The form of a refracting surface materially affects the direction of rays of light. In passing through a plate of glass, the refracting power of which is gi-eater than that of air, if its two surfaces are perfectly plane and parallel to each other, a ray of light passes on unrefracted ; or, if it be so, the angle of deviation as it enters being equal to the angle of deviation as it passes out, and as these angles are on op- posite sides of the ray, the direction line, after being tAvice refracted, will be parallel to its original direction. If the two surfaces of the medium incline towards each other at an angle, as in the ordinary prism, the course of the ray of light, after its second refraction, is not in its original path, but is deflected away after passing through the medium, according to the angle formed by the intersection of the two surfaces. Prisms, the surfaces of which are inclined towards each other at a sufficiently great angle, do not transmit any ray of light which is incident on the second surface, in such a manner as that its corresj)onding angle of refraction would exceed 90 degi'ees. Under these circumstances, rays of light pass out through one or other of these surfaces, after being reflected once or oftener. Ophthalmoscopic reflectors are sometimes made of this kind, perforated with a small hole, so that some of the rays of light returning from the patient's eye may reach the eye of the observer. Meyerstein was the first to employ such a reflector. A refracting surface which is the segment of a sphere * The angle of refraction — that i?, the angle which the direction line of a ray so deflected makes with a straight line (or perpendicular) drawn through the surface of the medium, and at right angles to' it — bears such a relation to the angle of incidence, that for the same media the sines of the angles of inci- dence and refraction are always similarly proportioned to one another. Thus, if we represent the sine of the angle of incidence of a ray passing from air into glass by the number 3, and the sine of the angle of refraction of the same ray by 2, then the sine of the angle of incidence of another ray passing from air into glass be (5, the sine of the angle of refraction of the second ray will be represented by 4.— Dr. G. Rainy's ' Theory of the Ophthalmoscope.* CONVEX AND CONCAVE LENSES. 25 will either have a common focus, or, after refraction, rays of light will proceed in a parallel direction with their original course. A refracting surface whose convexity is presented to a medium of less refracting jiower — as, for examj)lc, the cornea in relation to the atmosphere — condenses the light it refracts. On the other hand, a refracting surface, concave towards the less refracting power, disperses the light which passes through it. The double convex lens is a transparent body having two spherical refracting surfaces, convex towards the atmosphere, a medium of less refracting power, and with a common axis. Incident rays, after having been refracted at the two surfaces of the lens, have the same focal direction. There is a point in the axis of every lens through which, if we draw a straight Une in any direction, it will make equal angles with the two surfaces at the points where it cuts them. Rays of light passing through this point will be refracted as if they had passed through two plane refracting surfaces parallel to each other, which amounts to the same thing as if it had passed through without being refracted at all. This point in the axis of the lens is its optical centre, and a line drawn through it and the focus of an incident pencil of rays is the optical axis of this pencil. The optical centre of a double convex lens, having equal radii of curvature, is equidistant from them, and the focal distance is equal to the radius of curva- ture measured from the centre to the surface. In a double concave lens we have the two surfaces of the medium of higher refracting power, so opposed to the rarer as to produce a dispersing effect upon light which has passed through it, instead of condensing it, as would be the case with a double convex lens. Indeed, all the remarks with respect to the latter may be applied in a reverse sense to the biconcave lens, always bearing in mind, " If the surface of the medium whi(!h has the higher refracting power presents a concavity to that which has the lower, and if the rays com- posing the incident pencil have their focus between the re- fracting surface and its centre of curvature, the rays of the 26 DIOPTRICS. refracted pencil will diverge less than those of the incident l^encil, when the light is entering the medium of higher re- fracting power, and they will converge more than those of the incident pencil, when the light is re-entering the medium of lower refractmg power;" that is, on its passage out through the second surface of a biconcave lens. In consequence of the compound nature of light, its severally component rays are not only differently coloured, but have different refrangibility, which give a different index of refraction for each transparent substance. In the case of lenses, form or curvature, here, produces a sensible effect — so much so, that the rays of light which faU upon them at a distance from the axis, intersect those that fall nearer to the axis ; and therefore, from being refracted nearer than their principal focus, slight indistinctness is produced — an effect known as spherical aherration. The lens having the least amount of spherical aberration is a double convex one, whose radii are as one to six. Any augmentation of this curvature not only shortens its focal length, but increases spherical aberration. For optical pur- poses, it is not enough that the image of an object produced by a lens shaU be distinct in its lineaments, which it will be in proportion as the spherical aberration is effaced, it must also be sufficiently illuminated to affect the eye in a sensible degi'ee. Now the intensity of the illumination of such an image will be proportional to the number of rays, proceeding from each point of the object, which are collected upon the cor- responding point of the image ; and it can be readily shown that this will depend upon the angle formed by Knes drawn from any point of the object to the extreme edges of the lens. Indistinctness is also produced by chrmnatic aberration at the periphery of the lens, and must not be entirely disregarded. The extent of chromatic aberration is measui'ed by the in- terval between the red and violet images, and is termed the dispersion of the lens. No single lens can be produced en- tii'ely free from chromatic defect ; but since this is one of THE EYE AS A DIOPTRIC INSTRUMENT. 27 little or no moment in its employment with the ophthalmo- scope, I need not further enter upon the subject, and have merely to remark, that the eye is truly achromatic, is proved by the fact that the objects we behold are not edged with coloured fringes, as is the case with all non-achromatic lenses. But if, by any means, an object is seen out of focus — that is, so that its image shall fall either before or be- hind the retina — achi'omatism ceases, and coloured fringes in circles of dispersion immediately become apparent. We may therefore conclude that the natural achromatism of the eye compensates for most of the imperfections inhe- rent in the formation of lenses. And likewise that the re- fracting surface of the cornea produces a considerable con- densing effect upon the rays of the light as they pass through it. The Human Eye as a Dioptric Apparatus, and its Hypothetical Equivalent. The construction of the eye for the purpose of seeing, ex- hibits an arrangement and character of parts that have been not inaptly compared with those of an ordinary camera ohscura. The plate of ground glass, on which the image of the object is formed, figuratively represents the retina ; the inclosed box, with its stops to intercept the more oblique rays, is the chamber of the eye, with its admu*ably adapted curtain, the iris ; whilst the crystalline lens is the correlative of the glass one in that popular art-instrument. Rays of light reflected from any object will, after passing through a small pin-hole, form an image of that body on a screen, without the inter- vention of any special optical apparatus. Let the pin-hole represent the aperture of the pupil, and the screen a sensi- tive retina, and we have what may be termed a radical type of the organ of vision. Situated and circumstanced, however, as is the living eye, it is necessary that provision be made, not only to support and distend the parts, but that the media 28 THE HUMAN EYE. and structm-es employed should possess the transparency, and have, besides, a peculiar contrivance to harmonise the pro- perties of the different elements engaged in that wonderful economy, the object of which is sight. The laws of light, accordingly, and the varying refracting powers of substances of different densities, are accommodated to each other in the eye by the interposition of an organised body which has a something more than the form : — the character and the actual purpose of a common lens. Further, to complete every requirement, we have spread over, and in fact arising from, the tissues of the eye, a double layer of the finest muscular fibres, which are firmly attached to the edge of the contain- ing capsule of the crystalline lens. These collectively, are called the ciliary muscle, are under the control of the ner- vous system, and, contracting or elongating according to cir- cumstances, adjust the focal distance of the lens, with the nicest delicacy, to the point of distinct vision on the retina. The human eye presents to the passage of light three curved surfaces : 1, the cornea; 2, the anterior, and 3, the posterior surfaces of the crystalline lens. The rays have also, before impinging upon the retina, to pass through four trans- parent media of different densities or refractive powers. These curved surfaces are not exactly spherical, and their centres are not exactly in the same line ; so that the principle al- ready adduced cannot strictly be applied to the circumstances of a h\iug eye. The general effects produced, however, by this combination is the same as that of a double or biconvex lens, or of a single spherical refracting sm-face, having its convexity towards a medium of less refractive power. An explanation has been given of the optical problem involved, by assuming that very small portions of these surfaces are spherical, each having a centre in the same straight line di'awn through the vertex of the cornea to the centre of the macula lutea of the retina, and which would represent a com- mon optic or visual axis. Listing was the originator of this h}^3othetical solution of the many difficidties and apparent anomahes that arise in reconcihng theoiy with actual fact, listing's ideal eye. 20 from the compound structure of the human eye, and from the want of exact knowledge of the powers and values of the different refracting surfaces and media. And this sugges- tion has been acted upon by every scientific ophthalmoscopist who has since sought to give the abstract theoretical inform- ation necessary to understand properly the use of the instru- ment. None appear, however, to have improved upon the original proposition, and which accordingly I proceed to give in Listing's own words*-. " Indeed, by considering these vertex portions of the refracting surfaces of the eye as spherical segments, and their centres as placed on the optical or visual axis, we have trans- formed the eye into a system of spherical refracting surfaces, of which the centres are all the same straight line ; and this may well be called an ideal or diagramatlc eye. Of course we can apply all the principles (dioptric) just developed to such an ideal eye without further imitation. It must, how- ever, be always remembered — and, owing to its importance, a repetition may be allowed — that all the principles, &c. hitherto developed are valid only for those rays that form very small angles (strictly speaking, infinitely small) with the axis, and which at the same time strike the refracting sur- faces very near their vertices, so that the angles of incidence may be extremely small. An example may render this more striking. If this page be placed eight inches from the eye, and the number of the page be the part fixed upon, it must not be expected that the pencils of rays proceeding from the letters immediately beneath will be refracted according to the same laws as the rays proceeding from the number fixed : the former rays would form too great angles with the axis ; hence their course cannot be at all determined by the con- structions previously given. Owing to the compound nature * I have the high authority of Helmholtz (who himself employs Listing's formula) also to the same effect with resi)ect to, at least, one continental writer upon the subject. He remarks, in his ' Theorie der Augenspiegel,' that the " improvements which Stelling von Carion has sought to introduce into the said hypothesis, I cannot acknowledge to he such." 30 THE IDEAL EYE. of the light, a mathematically exact image is never formed on the retina ; accordingly we may readily understand that objects at different distances are seen with equal distinct- ness, provided their images are not attended by too large circles of dispersion. The eye is practically accommodated for a line, and not for a point — a fact especially pointed out by Czermak, who has called it " the line of accommodation ;" its length varies inversely as the rate of increase in the circles of dispersion ; and the more slowly they advance, the longer it wiU be." These circles of dispersion describe the condition of a bundle of rays of refracted light after or before having been brought to a focus on the retina. In the ideal eye, parallel rays come to a focus before or behind that membrane, thus forming upon it what we term circles of dispersion. It wiU be more perfectly understood that, in the diagrams I am about to give with my discussions of the two different methods, the direct and indirect, of examining the eye with the ophthalmoscope, the eyes represented are supposed to be homogeneous, or possessing one refracting spherical surface, which is the hypothetical equivalent of the various surfaces and media in a real eye. A higher index of refraction given than is the real equivalent of the actual media, preserves aU the proportions between the natural differences, and also of the distances of the cornea and retina from the optical centre, nearly unchanged ; and so far as concerns any conclusions important to ophthalmoscopists, the results obtained from the equivalent, or hypothetical eye, may be regarded as if quite accurate. Neither the rules nor principles laid down with respect to this hypothetical eye refer to any other rays of light than such as faU perpendicularly — horizontally — on the spherical refracting surface in or very near its vertex, and which ac- cordingly suffer no change in their direction after having been refracted. This, therefore, presumes a very small pupil, as the image of objects in a plane perpendicular to the optical axis must be formed on another plane perpendicular to its ILLUMINATION OF THE EYE. 31 axis, which can be true only of a very small portion of the retina. This circumstance affords me the opportunity of illustrating the rigid character of Listing's ideal eye, and com- paring it with the beautiful adaptibility of the natural eye, abounding with jn'ovisions for the proper refraction of rays falling at every angle upon the convex surface of the cornea, thus producing perfect images of lateral objects upon the retina. Whilst, therefore, the approximate results of exact demonstration upon hypothetical data can be fully relied upon in explaining the general dioptric phenomena of the human eye, there are still many evident provisions for special purposes, which, with our present knowledge, can be no further explained than by referring them to natural deviations in the refracting surfaces and media of the eye, from the simple and uniform type found so convenient in mathematical optics. Artificial Illuminatio7i of the Human Eye. It is by the aid of artificial illumination alone, that an observer at any time may so place his own eye in the axis of the vision of another, that rays of light reflected from the fundus of the eye observed, can enter and produce in his a sensible impression of what is there to be seen and noted. This is done by connecting some reflecting surface with the eye, in such a manner that, when looking at the object, it throws off in the line of vision, or nearly so, rays of light, which, being again reflected, come back in the same direction, and are then made to pass through the pupil and impinge upon the retina of the observer. The first idea, in fact, of the ophthalmoscope is due to the incidental observa- tion of Von Erlach, which fell from him in the presence of Helmholtz, that he could sometimes see, by the reflected light throAvn off from his spectacle-glasses when examining a case, the fundus, or internal posterior surface of the eye. He was perfectly aware of the theory of his observation — namely, that the glass of his spectacles acted as a reflector to rays pro- 32 ILLUMINATION OF THE EYE. ceeding from the light, and that those which passed in a paral- lel direction with the axis of mutual vision, between the observer and the observed eye, returning in the same line, produced this remarkable effect, one which has led to such important results in ophthalmic surgery. Without entering upon the more abstruse and exact con- siderations which define satisfactorily the respective advan- tages under given circumstances (the arbitrary conditions of all mathematical speculation) that arise from the use of con- cave, convex, or plane surfaces, as reflectors of light, it is sufficient for me to state, that, practically, as far as my own experience goes, the slightly concave or plane perforated glass mirror is sufficient for all the purposes of ordinary practice. Of course, I sacrifice here something of a reputation for rigid, scientific exactness ; but I compensate myself by feeling assured that, however future progress may authorise more profound studies in connection with the use of the ophthalmo- scope, at present these would only interfere with the general reception among practitioners of a most useful and invaluable assistance in diagnosing eye disease, by conjuring up ideas of difficulty, that really belong to other inquiries than those which are sufficiently satisfied by the emphatic evidences of changed structure which the ophthalmoscope discloses to the examining eye of the oculist. To illuminate the eye of a patient properly, it is better that it should be done in a darkened room ; but the admission of a little daylight, at the same time, is found not to interfere materially with the distinctness of the objects seen. The larger the pupil, also the gi-eater is the facility of observation. This, then, is an additional reason for taking the patient into a darkened room. As a rule, where no lens is used, the whiter the source of artificial light, and the nearer the" reflector is to the eye examined, the more effective and uni- form will the illumination of the fundus be. In the great majority of cases, however, it is necessary to use a biconvex lens, to condense the light and bring the rays quickly to a focus on the retina ; and if the transparent media are in no BY ARTIFICIAL LIGHT. 33 way obscured, there is no difficulty, after one or two trials, in lighting up the whole area of the fundus oculi. The principal object is to throw the spectral light of tlie reflector, as near as possible, full on the centre of the eye. To effect this readily is first to observe the manner in which this reflected image is produced on the face of the patient before directing it full on to the eye. Whatever little trouble beginners may meet with in lighting up the chamber of the eye, from the unma- nageableness of the reflected spectrum, will be, however, best overcome by practising a little, as if in an examination with the ophthalmoscope, and throwing the reflection from the mirror upon a card suitably placed, upon which is described a small circle to represent the pupil. Although the use of the lens obviates the inconvenience altogether, it will be useful to mention, that in some eyes, perfectly free from any obscurity, yet not in a normal state with respect to the refractive powers of the media (such, for instance, as in the hypermetropic, or where the crystalline lens has been removed), it is sometimes difficult to illuminate the fundus, from the very contracted size of the luminous space in the centre of the circles of dispersion, which in such cases falls too far behind the retina. To obviate this, it is only necessary to remove the reflector and the lamp a little further from the patient, or by increas- ing the intensity of the light, the field of the reflector pro- duces a corresponding effect upon the circles of dispersion, and the size of their luminous centres. It is evident that, if the artificial light employed was of uniform intensity (wliich it is not, as the flame has a dark centre), and if the surface of the mirror reflected equally from every point, a maximum uniformity of illumination would be obtained ; but as the mirror generally used has also an aperture in the centre, it will be found in practice that a corresponding dark place in the centre of the illuminated area of the fundus of the eye interferes with a uniform brightness, and must be allowed for in conclusions arrived at. There is also another interference with complete illumination, owing D 34 ARTIFICIAL ILLUMINATION to an appearance in the field of an image of the flame, which, when the pupil is small, occupies nearly the whole of the area otherwise visible. The inexperienced eye naturally adjusts itself to this bright reflection, rather than to the patient's retina, which by comparison is much more faintly illuminated. These adverse circumstances, to which I have draAvn attention, are soon overcome by a short practical acquaint- ance with the ophthalmoscope, as the discoveiy is then made that they depend chiefly upon the focal relations of the mirror to the eye examined, and that the inconveniences spoken of are obviated by producing on the retina circles of disper- sion, which at once cover with light the dark space referred to. In all cases, the centre of the visible area should appear brightest to the observer's eye, the parts towards the circum- ference being more faintly seen ; and this can generally be attained by approaching as near to the eye observed, as cii*- cumstances and the required adjustment for illuminating purposes will admit of. It is now weU known that a suflicieutly large area may be illuminated with excellent effect by employing a common paraffine lamp, with a circular wick, the Hght of which is thrown into the eye by a concave glass mirror, two inches in diameter, and having a focal length of six or eight inches. The perforation in its centre should not exceed one-sixth of an inch. The biconvex lens now generally used to condense the reflected light of the miri'or, has a focal length of from two, to two and a half inches. Thus prepared, " it is not necessary that we should attain the maximum in this res- pect with theoretical accuracy, and it is impossible in ordi- nary practice ; but the observer will find that he can make an approximation to it by altering the distance between the flame and the reflector, and that between the lens and the patient's eye, taking care that his own eye is at the proper distance from the lens."* * Rainy, page 60. OF THE INTERNAL EYE. 35 Mode of examining the Internal Eye. In the theory of the ophthalmoscope, the mirror is sup- posed to be employed only for the purpose of throwing light into the chamber of the eye. Practically, however, it is made to subserve another and more imj)ortant object. The small aperture in its centre allows an observer so to place himself in the axis of the vision of another, that rays of light reflected from the fundus oculi of the latter shall pass into his own eye ; and a view of the interior, nerve and vessels, is thus easily obtained. But although this is attainable by the ob- server placing his own eye at the somewhat inconvenient distance from the eye observed of not more than two or three inches, as may be supposed, the very limited view of the image obtained and the small number of rays which enter the eye under these circumstances, render such an examination tedious and trying, both to the observer and the observed ; to the latter, even painful at times, owing to the concentra- tion of the rays of light upon an over-sensitive retina. We usually talk of the direct and indirect methods of ex- amining the internal eye. Fig. 4. Fig. 4 is intended to illustrate the direct method. The ophthalmoscope is supposed to be arranged for normal vision ; but the relative distance between the eye of the observed and the observer is not accurately shown in the diagi'am. a is D 2 36 MODE OF EXAMINING the eye of an observer, placed behind the central aperture in the mirror, b, which collects the rays of light from a candle or lamp at d, and reflects them into the eye of the patient at c, where they are received on the fundus in circles of dispersion, described between f, f. The observer sees a virtual erect image of the fundus, magnified by the refracting media of the eye. In the myopic, we obtain a general view of the fundus in this way ; but, in such a case, it becomes the indirect method as from the greater elongation of the globe the whole is more or less indistinctly seen, we require to use a concave lens before a perfectly clear outline is obtained. In the indirect method of examination, the observer re- moves the mirror to the ordinary distance of distinct vision, from the eye of the observed, and places before the latter a biconvex lens of about two inches focus. If the returning rays are parallel, or very nearly so, and the biconvex lens is held two inches from the eye of the patient, then an inverted aerial image of the fundus wiU be formed two inches from the lens, or four inches from the patient's pupil, and conse- quently it will appear so much nearer to the eye of the sur- geon. If we wish to increase the size of the image, or give better definition to it, another lens, called an amplifying lens, of greater focal length must be employed behind the mirror, as an eye-glass. This not only increases the apparent mag- nitude of the image, but enables us to approach nearer to the eye of the patient ; in other words, diminishes the distance between the eye of the observer and the observed. The following diagram, fig. 5, conveys a tolerably correct idea of the indirect method of examination. A is the eye of the observer, b the mirror, and e the biconvex lens of short focal length. This lens, it will be seen, receives the re- flected rays of a candle d, and concentrates them upon the fundus, from which they are retui'ned, and an enlarged inverted image is formed at some point between it and the eye of the surgeon at A. The lens, in this case, concentrat- THE INTERNAL EYE. Fig. 5. 37 ing the rays of light from the mirror, adds to its illumi- nating power and lessens the circles of dispersion ; thus also a larger and clearer view of the back of the eye is obtained. There is a first reflection of the flame from the surface of the cornea, which must be obviated by inclining the mirror more or less obliquely to its surface. This reflection is often an annoyance to beginners. In all cases, the visible area increases in size as we with- draw the biconvex lens from the patient's eye ; in very many cases, it will be found that an eye exposed to the strong light of the mirror has a tendency to fall into a state of ad- justment for distant objects, especially if atropine has been employed to dilate the pupil. If a biconcave lens be employed, an enlarged erect virtual image of the retina is seen — an effect due to the dioptric media of the eye in conjunction with the lens, converting it into an ordinary telescope. Fig. 6. In case either the eye of the surgeon or the patient be myopic, then it becomes absolutely necessary to use a concave lens, to give the requisite degree of parallelism, or divergence 38 DIRECT AND INDIRECT METHODS. to the reflected rays, as in fig 6, otherwise a confused ill-de- fined image affords only negative results. The concave lens c c, should in the one case he placed behind, and in the other before the mirror, to produce a perfect image of the fundus at d, d. Comparison of Direct and Indirect Methods. Finally, when the respective advantages of the dii'ect and indirect methods of examination come to be fairly considered, the superiority of the latter, in most cases, must be admitted ; and when once the illusive displacement of the fundus oculi has become inoperative, by mental adjustment, then the in- direct method really enables us to get a much better idea of the relative position and the proper magnitude of objects ; larger portions also of the fundus oculi can be brought under observation at the same moment. Details come out with a distinctness and exactness of definition which is not always the case in the direct method of examination. A beginner will perhaps be less embarrassed by using the direct method ; he is not perplexed by any inversion of the image which is projected clearly from the fundus, and admits of a tolerably close examination ; he may, however, find this, if too prolonged, very fatiguing. To become famihar with both methods is the rule, as the observer will then be less liable to misinterpret alterations in structure, and much less likely to overlook points of diagnostic value, than if he were to rely exclusively upon one. 39 CHAPTER III. STRUCTURAL AND FUNCTIONAL ACCESSORIES OF VISION. MUTUAL RELATIONS OF THE STRUCTURAL ACCESSORIES OF VISION. ADJUSTMENT AND ACCOMMODATION OF THE EYES. The Structural Accessories of Vision ; their mutual Relation and probable Functions. The structural accessories of Yision contained within the eye require particular consideration. A close anatomical description of the parts, however, is not necessary, as every member of the profession must be sufficiently well acquainted with their general character. My present purpose is chiefly to direct attention to recent microscopic examinations of the cornea, the iris, the crystalline lens, the ciliary muscle, the re- tina, the choroid coat, and the humours of the eye, as well as to those investigations which have been made with special refer- ence to the discovery of the proper function, and the exact par- ticipation of each part in the process of adjustment for the pur- pose of vision. A knowledge of the deviations from a normal condition, which are sometimes very considerable, is also abso- lutely necessary for the effective use of the ophthalmoscope. This can only be obtained by becoming perfectly familiar with the natui'al relations of the several parts, their mutual influence upon each other, and Collectively upon the formation of the eye. It may not, therefore, be altogether out of place to insert here an enlarged diagram of a segment of the eye, as it wiU be convenient for reference in the further discussion of my subject. 40 STRUCTURAL ACCESSORIES Fig. 7. Pig, 7. — An enlarged vertical section of the Eye: c, the cornea; s, the sclerotic coat ; a, c, the anterior chamber ; between which and^, e, the pos- terior chamber, lies the iris and its pigmental coat ; and to the left, c, w, the ciliary muscle and ligament ; c, i, the crystalline lens ; «, A, the vitreous humoui-. The dotted line, ^, indicates the direction the knife takes in the operation for division of the ciliary muscle. The external envelope of the eyeball is formed by a dense fibrous coat, which is divided into a smaller anterior transpa- rent structure, the cornea, and a larger posterior and opaque part, the sclerotic. The healthy cornea is one of the most transparent sub- stances we know of, and it is so constructed us to allow rays of Kght to penetrate the eye which would otherwise be lost by reflection. The vascularity of the extension of the true skin over the cornea is not now disputed, nor is it difficult, with a good microscope, to make out the probable situation of the vessels in that organisation so distinctly traceable in a double layer of epithelial scales, the lowest series of which oflE'er, in an erect position and denser texture, an appeai'ance of greater contrasting vitality than do the loose and appa- OF VISION. 41 rently flaccid condition of tlie more superficial scales. The extreme sensitiveness also of the conjunctival covering of the eye to the minutest extraneous body coming in contact with it, is clearly demonstrative of an ample supply of nerves. The internal structure of the cornea has attracted particular attention, as being the chief seat of the more obvious diseases of the eye, and fortunately offering greater facilities for accurate diagnosis than the more deeply situated structures. It has been satisfactorily determined to be a continuation of the sclerotic coat, the fibres of which' have here assumed a close laminated texture, the number of la- minae in a vertical section exceeding one hundred. After considerable pains to ascertain the real natui'e of these fibres, and, besides my own, following closely the detailed examinations of others with the microscope, I have adopted the following conclusion : " that the arrangement and connection of these laminse result from the mass of the fibres passing in the curve of the cornea, but none of them reaching through- out the whole extent of it, and not being continued in their whole course in precisely the same line, so that some fibres are constantly terminating and passing into the layer above or below, whilst others are constantly arising; that whilst the general mass pursues a longitudinal course (the cornea under examination, it must be observed, being laid flat, and not in the usual position in the living eye), from one margin of the cornea to another, and the fibres, for the most part of their length, lie side to side in parallel layers, or nearly so, their terminations pass into other layers, and thus connect them together. This mode of connection satisfactorily ex- plains why the cornea should be stronger and more resistant in the direction of the lamellae than between them." * Virchow has also described lamellae of fusiform and stellate, nucleated cells, which he regards as " corpuscles of connective tissue, or corneal corpuscles." He considers that the nutri- ent fluid of the cornea is chiefly conducted and distributed throughout its substance by these stellate cells. This view, * Nunucley — ' Organs of Vision.' 42 STRUCTURE OF CORNEA. he observes, receives confirmation ; " as we find, in diseases oi' tlie cornea, these cells frequently contain fat corpuscles, and, in exceptional cases, according to Bonders, even pigment in their interior." " If," says Virchow, " we view a section, made from the cornea of a patient suffering from keratitis, with a high power, we shall see that the change is essentially seated in these corpuscles, or cells of the cornea ; and that, in propor- tion as we approach the clouded spot, either from without or within, the little narrow cells become larger and more cloudy. At last, we find them presenting almost the appearance of sacculated canals or tubes. Whilst this enlargement of the elementary structures, this acute hypertrophy, is going on, the contents of the cells are, at the same time, becoming more cloudy, and proceeding on to opacity of all the structure ; except the basement membrane, and this appears to be un- affected. This cloudiness of the contents is in part occasioned by particles of a fatty nature ; so that the process seems to have begun to put on the character of a degeneration of structure." * During my own examination of the cornea, I confess to have been much interested in the question of the distribution of its nerve-supply. Schlemm was the first to demonstrate the presence of nerves derived from the nervuli ciliares and passing into the fibrous layer of the cornea. From twenty to thirty, or more, trunklets are distinguishable round its border, forming a numerous and wide-spreading network, extending throughout the whole cornea. " Bifurcations of the original tubes present themselves but rarely in the trunks of these nerves ; and never in the plexus formed by them — the actual con- dition of which, however, can scarcely be fully investigated, on account of its translucency. This plexus lies in the proper cornea, but nearer to the anterior surface ; and since no trace * Virchow's ' Cellular Pathology.' Fatty degeneration of the cornea, and its pathological indications, have been fully described by Mr. Canton. See ' Lectures,' in the Lancet, 1861-2. NERVES OF COllNEA. 43 of free terminations of nervc-filircs can be seen, it would appear to consist solely of anastomosing twigs of the finest kind ; therefore, if not in the form of loops, still some connec- tion of the ncrve-tubcs with one anotlier may he assumed." Nerve aud stellate cells of cornea, magnified 300 diameters, a, Nerve cells, b. Stellate cells. Dr. His describes and figures a somewhat similar arrange- ment of the nerves of the cornea ; but he denies their distri- bution throughout the stellate structure, as shown in my illustration. I therefore think it desirable to give this ana- tomist's views. " The greater part of them," he writes, " are derived from the posterior ciliary nerves, the lesser from the small trunks of the conjunctiva bulbi. On entering the cornea, their branches are partly filled with tubular matter ; some have a, dark double contour ; others, a pale colour, evidently contain- ing nuclei. In this respect there is no prevailing rule ; as one may occasionally observe pale gelatinous fibres entering side by side, or in the same trunk with fibres containing dark tubu- lar matter. 44 NERVES OF CORNEA. " In every instance, however, the fibres which, on enter- ing, presented a dark contour, very soon lose their medullary contents, become pale, and, in their further progress, show pale, granulated, oblong or staff-shaped nuclei. At varying distances from theii' entrance, the small trunks either sepa- rate into equal branches, or send off a single fasciculus of a few fibres, occasionally even a single fibre only. The second- ary small trunklets again anastomose ; and, after splitting up into numerous branches of smaller size, unite by means of their branches, and form a larger network, spreading through- out the cornea. Within these small trunks of medium calibre, one has the opportunity of observing divisions of primitive fibres, and these divisions usually take place near the nucleus. In the minute fibres, the division takes place in such a manner, that at every point of division a small triangular enlargement presents itself, in which is seen a small nucleus. In tracing more closely fibrillse arising from the division, one may observe that they do not show an abrupt termination, but proceed to, and enter, a similar triangular enlargement as those from which they took their origin ; so that they form a network of most minute fibrillse, as Kolliker conjectured. The triangular enlargement may probably be looked upon as a kind of ganglionic nerve-cell. " With the cells of the cornea, and their offsets, the nerves do not stand in any anatomical relation. The accu- rate observer cannot well mistake the smaller fibrillse for the tail-like processes (offsets) of the corneal cells; the nerve- fibres being distinguished by their peculiar brilliancy, their straight course, and (excepting the nucleolated enlarge- ment) their unchanging calibre. In doubtful cases, the criterion would be that of tracing the connection of the fibres with the chief nerve-trunk. In regard to the extension of the nerves throughout the thickness of the cornea, it is a very limited one; and it was an erroneous conclusion of Strube to admit the presence of nerve-fibres in all the strata of the cornea. Accurate investigation shows that branches, dipping even into the deeper strata of the cornea, very soon NERVES OF CORNEA. 45 come towards the surface, and spread into terminal divi- sions there. " The chief seat of the nerves of the cornea is in the anterior third of the membrane, and it is only exceptionally that single trunks are to be found in the deeper portions ; in the jiosterior third, probably none. The most minute ramifications take place immediately below the surface, and to this it is owing that we see those small branches which remain in the deeper portions forming sharp angles. " The nerves of the cornea in their primary arrange- ment consist of fusiform cells, with long oval nuclei, as shown in a human foetus at the end of the fifth month." * His, it will be seen, denies the existence of nerve-cells in the strata of the corneal substance. I believe that these nerve-cells are connected with the nerves of Schlemm ; and although my sections do not always show the regular-looking reticulated arrangement represented by the artist in jig. 8, which arises from the great difficulty experienced in cut- ting fine sections of so delicate a structure, nevertheless there is no difficulty in making out the nerve-cells, with well- defined nuclei, embedded in granular matter — seen at a — as separate from the layer ef stellate cells, h. It is most inter- esting to compare the characteristic identity of the neiwe- cells of the cornea, although so much smaller, with the very similar appearance of those displayed in sections of the nerve-cells of the cerebral substance, and of the spinal column. The repetition of the same formed bodies in an evi- dently organised system of distribution, is too apparent and significant to admit of dispute, and doubtless have an im- portant bearing upon the perfection of accommodation, as wtU as that of either separating, admitting, or arresting only just those rays of light that are necessary to good vision. Loops of capQlary vessels, derived partly from the con- junctiva, and partly from the sclerotic, run across the margin of the cornea, and either at once form single loops, or unite * Dr. "W. His — ' llistoloprie der Corneii.' 46 STRUCTURE OF CORNEA, with each other in a network of vessels around its circum- ference. With regard to the relation of the cells to the lymphatics, nothing certain is known ; but, although it is not possible to determine this for want of sufficient data, nor how nutrition is maintained, yet, that the cornea is a more com- plicated and highly organised structure than it had hitherto been believed to be, is now very generally admitted. The elastic lamina is the third layer of the cornea, possess- ing specific characters, which readily distinguish it. It is easily separated, and, although very hard and dense to the knife, may be torn with little effort. It is remarkable for its elas- ticity, and curls up always in a direction contrary to that in which it is laid down — a property no doubt very available in assisting to adapt the curvature of the cornea to the re- quirements of adjusted vision, as it seems to be of the nature of a compressible spring, adapted to its posterior surface. Immediately behind the cornea, which it supports, is the aqueous humour, contained in a space divided by the iris into an anterior and posterior chamber, communicating througli the pupil. By equally distending the parts between the cornea and the crystalline lens with a fluid, the freest move- ment is ensured to the pupillary margin of the iris. And here we have a liquid meniscus, forming together a concavo- convex lens of somewhat less density than the cornea itself : such an arrangement materially assists in rendering the eye the perfect achromatic instrument it practically is. In quantity the aqueous humour seldom exceeds six grains, of which the posterior chamber, which is much the smaller of the two, contains less than an eighth part. The iris is the perforated curtain, or diaphragm, which, besides regulating the amount of light admitted, materially assists in preventing spherical aberration, by excluding all rays that strike the eye too obliquely to be brought to a proper focus upon the retina. It hangs in an exact plane in •the aqueous humour, its posterior surface being in close proximity to the lens. The outer margin of the iris is attached to the corneal juncture with the sclerotic, along points cor- IRIS AND CnOROID. 47 responding to the border of the clastic Lamina. The anterior surface reflects the light, and its colour depends upon the pigmentum nigrum or uvea, being l)lue or grey where the posterior surface only is covered, and brown where a con- siderable quantity is mixed among its fibres. Except in albinoes, the posterior surface always presents a thick layer of this dark colouring matter, which, in this situation, l)csides assisting the choroid in al)Sorbing the rays of light, after striking the retina, also renders the iris perfectly opaque, and thus prevents the transmission of light through its deli- cate and intimately woven fibres. The nature of this pigment, the purpose of which is self- evident, represents the dark colouring matter of the choroidal veins, determined with an economic object to a greater develop- ment over the whole of the internal surface of the choroid and iris, where it performs the office of the black coating on the inside of the tube of a telescope or microscope. Recent observations have, in fact, confirmed what had long been presumed, that the pigment membrane of the eye was analogous with the deepest layer (rete Malpighii) of the skin. As this exists in a colourless state in the albino, it was in- ferred that the pigment membrane would also be found to be so, and a strongly corroborated fact, I consider, accompanied this discovery of Mr. Wharton Jones ; for, instead of the usual hexagonal, flat, transparent, central bodies, connected by their edges and loaded with dark colouring matter, plates of a circular form were found without pigment ; the difference in form being, no doubt, due to the absence of lateral pressure, which, when abundantly produced, would cause the choroidal pigment cells to assume an hexagonal shape. The presence of the pigmentum nigrum on the whole of the internal surface of the choroid, the iris, and the ciliary processes, serves, in a measure, to connect all these several accessories of vision in one general view of functional jmr- pose — a supposition which is not weakened when their actual structure comes to be examined, being made up of blood- vessels and a fibrous tissue common to all, the proportionate 48 STRUCTURE OF IRIS. development of which seems chiefly to distinguish their specific characters. To suppose that this extensive vascu- larity is alone intended for a due supply of the pigment, is not borne out by facts ; as, although we find this membrane present in albinoes, and fully developed, that function is not performed. Considered as a whole therefore, I am inclined to believe, from its situation, its structural character, and the probable nature of its office, suggested by all the surrounding circumstances, that the vascular system, which includes the choroid, the iris, and the ciliary processes, belongs to that class of erectile tissue which nature has specially provided to meet very opposite contingencies of blood-supply, occurring under conditions of great uncertainty. The structure and presumed use of the spleen, as the supplemental blood-reservoir, preserving the equilibrium of circulation in the stomach, whether at rest or during active digestion after a full meal, offers an analogy for the purpose of illustrating this point. Now, as the waking eye is sustained by ordinary means always in a state of watchful attention, resources of an ex- traordinary character are required to meet cu-cimistances of particular and earnest gaze, most frequently called up by mental emotion, sometimes by instinctive impulse, like a blush in the capillaries of the skin, and also by particular efforts, voluntary and involuntary, made to perfect sight by the necessary adjustment of the dioptric apparatus of the eye. This appears to me the great purpose of the choroidal vascular system, which, by a sudden and peculiar effort becoming distended with blood, materially alters the relative position of the parts concerned, and which again assume their quiescent position by a corresponding collapse when the necessity has passed away. The structure and functions of the iris favour this view of the character of the choroidal vascular system, as it exhibits a combination of blood-vessels, and peculiar fibrous tissue, arranged vnth reference to the special and distinct offices of its anterior and posterior suifaces. Keflected from the base of the ciliary proceeses, a continuation of the pigment mem- STRUCTURE OF IRIS. 49 brane forms an internal coat lying upon the higlily vascular texture of the iris, here consisting of a plexus of vessels, derived exclusively from the ciliary arteries : and taking a further argument from the great quantity of pigment de- posited, the intimate relationship of this surface with the choroidal system alluded to must, I think, be allowed. In front of this vascular layer, and more or less mingled with it, is the anterior surface, which consists of numerous delicate fibres, some arranged concentrically, but the greater part radially, and which so closely resemble the tissue of the ciliary muscle, that they are now generally admitted to be identical. In fact, some very accurate observers do not hesitate to say, that the anterior surface of the iris is a prolongation of the ciliary muscle, extended as it were over a reflected portion of the choroid membrane, which, together with its pigmental coat, constitutes the whole structure of the iris. Moreover, this important adjusting accessory of sight, the iris, by its delicate sensitiveness and mobility, exliibits the chief characteristics of the two-fold structure of the choroid cocit of the eye ; we may, therefore, infer from the nature of its duties, which are to regulate the amount of light admitted into the eye, and to preclude all rays but such as pass through the more central portion of the crystalline lens, that the choroid coat and its ciliary accessories, including the muscle, to which in its structure it is so intimately allied, are also included in the means provided to ensure the accurate adjust- ment of the eye, by assuming a condition of action or repose, accordingly as a sensitire retina measures its need for the due focusing of the rays of light, as coming from a near or distant object. This excitement of the choroidal and ciliary vessels is quite analogous to corresponding experience else- where, and in a very similar structure. The presence of food acts, unconsciously to us, upon the salivary glands, to prepare the stomach for its due reception ; and there can be little doubt that in some such manner light affects the condition of the choroid and retina, so as to admit, by anticipation, of a proper adjustment for the perfection of vision. E 50 CILIARY PROCESSES. The ciliary processes, as derived from the clioroid, will be found to afford corroborative evidence of the unity of design and i3ur23ose which connects the whole of the severally situ- ated membranes into one erectile system. These bodies constitute a fringe of numerously anastomosing Ioojds of the Fie. 0. 1, A slightly enlarged View of the Iris and Ciliary Processes, after wash- ing away the pigment. 2, Schlemm's Xerves of the Cornea, stained with iodine. 8, Fibres or Tubules of the Lens, magnified 250 diameters. choroidal vessels; and as they also contain elastic fibrous tissue, it is difficult to consider it otherwise than a continu- ation of that membrane. They rest in a series of radiating folds on the anterior surface of the vitreous humour form- ing the floor of the posterior aqueous chamber, upon the contents of which any alteration of condition from a relaxed to a turgid state must produce a corresponding effect upon the eye, by a kind of intra-ocular pressure, telling, as usual, particularly and primarily upon the curvature of the cornea. It has been shown how, in the structure of this latter, it is supplied with a highly elastic tissue, beautifully contrived for the contingency here pointed out ; so that, when the urgency ceases, without other effort, all the parts concerned resume again their ordinary quiescent position. Together with the aqueous humoui', the cornea forms a compound lens, the sur- face of which is evidently adapted for this ready alteration in its curvature ; and it would be strange, if, in any natural CILIARY MUSCLE. 51 contrivance for focal adjustment, a structure and means so sufficient for all purposes were found to be least concerned in the effect produced. A little instrument, formed for looking into the eye, with light thrown as usual from a con- cave mirror, is based upon this principle of afiecting the form of the cornea. A peculiarly formed glass cup is filled with tepid water, and placed upon the eye : the efi'ect produced is to flatten the cornea; examined through which, a beau- tifully distinct and magnified image of the fundus is seen. This contrivance has been called, by its inventor, Czermak, the Orthoscope. The character and position of the ciliary muscle is also favorable to this explanation of the problem of visual adjust- ment — the two directions of its fibres, separated as it were at the point called the pillars of the iris, one part proceeding to form the anterior surface, and the other being attached to the edge of the elastic lamina, which, by some anatomists, is actually described as passing continuously into this muscle. Motor power must be ascribed to, or as the object of, this arrangement; and, according to my view, it is found just where it is required, to regulate the due disposition of two really antagonistic influences — the elasticity of the cornea, and the erectile nature of the ciliary processes ; and the con- trol of which, a natural impulse, whether in l)irds, mammalia, or man, is thus enabled to hold as it were in hand.* * The first mention of the ciliary muscle appears in the writings of Sir Philip Crampton, in a paper describing dissections made on the eye of the do- mestic fowl, in 1818. Other anatomists, some time before — among whom we may mention Porterfield — noticed the peculiar structure, arid deemed it to be muscular, but advanced no sufficiently conclusive arguments in support of this view ; and it remained for Mr. Bowman to give a better and fuller descrip- tion of it, in his ' Lectures,' in 1847. Mr. G. Rainy, in 1851, made a series of examinations into the functions performed by it, the particulars of which he published in the Lancet, July, 1851. He suggests that the adjustment of the eye to objects at different distances may be effected by means of the ciliary muscle compressing the ciliary processes through the medium of the aqueous humour ; and thus, by alternate partial emptying and refilling of these pro- cesses, room is made in the globe to allow of the lens changing its position, and so altering its focus. E 2 52 CILIARY MUSCLE. I must here observe that my diagram of the sectional view of the internal eye (although a little exaggerated by the artist), Fig. 7, tliifers considerably from that given by Mr. Bowman ; inasmuch as I have not been able to make out the expanded form of the ciliary muscle as he represents it, but, on the contrary, I find the ciliary muscle and processes, as well as the suspensory ligament as it approaches the lens, so intimately associated with the vascular choroid, that it apj)ears to me better to describe them as a whole under the name of the choroidal system, as having reference to their action and functions in combination. The ligament of the lens, it may be observed, embraces it as delicate fingers would do a spherical body ; so that we might truly say, it is ' held in hand ' by it, for the purposes of adjustment and accommodation. This is better seen in the eyes of some inferior animals ; the rat for instance, an outline sectional view of which I give. Fig. 10. My drawing is made from a beautifully prepared transparent injection in the possession Fig. 10. Fig. 10. Sectional view of the Eye of a Rat magnified 150 diameters. Lens; i) /«, vitreous humour ; r, retina; Z, suspensory ligament, passing up to embrace the lens and join the ciliary muscle and processes; c, choroid. STRUCTURE OF CHOROID. 53 of Messrs. Smith and Beck. The parts, carefully preserved in situ, have been so little disturbed, that the true relation of the several membranes to each other are shown with a degree of accuracy unattainable by any other process ; indeed, without any of that derangement incidental to the knife of the most careful dissector. The choroid is not only the true structural origin of the ciliary processes, but also of the iris, and the ciliary muscle, constituting together the convenient generalisation I have called the choroidal system. Viewed separately, the choroid is a highly vascular membrane, contributing largely to the pari- eties of the eyeball; for this purpose it is strengthened by the addition of a peculiar fibrous tissue, and the true nature of which is more decidedly developed in the iris and ciliary muscle. Some anatomists, with whom I am inclined to agree, consider this tissue as interposed between the ar- teries on its inner surface, and the veins on the outer. A layer of capillaries accompany the former also, which Ruysch has successfully injected and separated from the larger vessels upon which they seem to repose. The veins of the choroid are equally numerous, and, from their peculiar course and, apparently, involved inosculation with each other, are called the vasa vorticosa ; and exliibit, under the microscope, the most curious arrangement of any vessels in the body.* The character of the structure, however, strongly suggests a relation of functional purpose, corresponding to that of erectile tissue, which is intended to meet circumstances of different degrees of excitement by a proportionate blood supply, and which as readily subsides when the stimulus is * " These veins are often found injected after death, and may be seen by simply removing the whole of the sclerotic coat. A better way of seeing them, is to cut out a third of the choroid coat of the sheep, ox, or horse, with the ciliary muscle, ciliary processes, and iris ; gently wash away as much of the colouring matter as possible, and very carefully spread the whole out upon a thin watch glass, the curved surface of which allows the membrane to lie smooth. When dry and viewed with an inch lens, not only will the vasa vorticosa be beautifully seen, but also the continuity of the ciliary muscle, ciliary body and processes, and iris, with the choroid." — Nunneley. 54 STRUCTURE OF CHOROID. ■withdrawn. If this be true, tlierefore, of the choroid coat, the natural conclusion is, that this membrane and its con- nections are principally concerned in effecting the mecha- nical changes of relative situation between the refracting media of the eye and the retina necessary for perfect vision under extraordinary circumstances. And it is difficult to conceive anything better adapted for this purpose than the character of the choroidal system generally — composed of muscular fibres— fully determined to be so by all liistological observers — and a highly vascular tissue, remarkable for its convoluted and lobulated inosculations : my inference there- fore is, that, as elsewhere where a similar structure exists, the distension of the latter with blood by an arrested circula- tion form fixed points of effective operation for the former ; and at the same time, in this particular situation, produce, by an actual increase of bulk, considerable modifications in the form of the eye. Any distension of the ciKaiy processes especially, must affect the focal relation of the refractmg media, either by pressing backwards upon the zonula of Zinn, and retracting the crystalline lens to a corresponding extent, or by affecting the cui'vature of the cornea by pressure exerted forward upon the contents of the aqueous chambers of the eye. And even should all this be deemed as not actually demonstrated, still the necessity of some sufficient agency to fix, by a kind of muscular effort, the optical centre of the lens exactly and steadily in the axis of vision, under all cir- cumstances of adjustment or accommodation, argues strongly for the purpose which the character and situation of the fibrous tissue of the choroid system seems well calculated to perform. It may be remarked, also, that the presence of an erectile tissue is not required for the secretion of the pig- mentum nigrum ; for which purpose alone, as I before stated, some physiologists contend that the choroid coat of the eye is intended to maintain the supply of. We find, in coloured peo- ple, a substance quite as freely produced by the corium^ which, however vascular in its texture, has not certainly been de- scribed as an erectile tissue. Indeed, to infer any thing more PIGMENTUM NIGRUM. 55 from the presence of tliis pigment than that the capillaries of the choroid, so much exposed to light, perform in the eye exactly the same office as those in the external skin, when acted upon by the direct rays of a tropical sun, would be exceeding fair analogy, and almost ignoring the specific function of the choroidal membrane, and one which I beHeve to be its chief characteristic. Of the pigmentum nigrum itself, I shall only give such a description as is required for ophthalmic purposes, presum- ing its more intimate anatomical and physiological characters to be sufficiently well kno"svn. That it is identical with the colouring matter of the skin, and is one of the most per- fect absorbents of light in nature, is now generally admitted.* And its use is equally obvious, placed upon the posterior surface of the iris ; it prevents the rays of Hght entering, ex cept through the crystalline lens, whilst that on the inner surface of the choroid lining the posterior chamber of the eye, most effectually absorbs the Kght after it has im- pinged upon the retina. The pigment is easily washed off from the membrane, which so plentifully secretes it, and it is as easily separated from it by abnormal lesion : in this latter particular it presents a feature of gome import- ance to be considered in connection with appearances in the eye when affected by disease. Mr. Nunneley directs attention to this circumstance ; and I have no hesitation in expressing my concurrence with the following remarks : " The arrangement of the pigment affords, I think, a satisfactory anatomical explanation of an abnormal condition which has hitherto not been understood — muscce volitantes. If any one, who has himself been subject to these motes, or has got patients who are so to draw figures of what they * Pigment particles are the granulous contents of the pigment cells, and are like ordinary elementary granules with the addition of colouring matter ; the latter may be removed by the action of chlorine. In the Tapetum lucidum, of the eyes of animals, the colour is not owing so much to Ihe pigment par- ticles, as to the way in which light is reflected, namely, in the same way as it is fi-om mothcr-of-pcarl. Coloured feathers and the scales of fishes owe much of thcii' beautiful colour' to a mechanical arrangement of similar pai'ticlcs. 56 PIGJIENTUM NIGRrM. complain of, will examine, as I have described, a portion of choroid coat teased out, he cannot fail to be struck ^vith the perfect resemblance of the two — the nodulated masses with connecting and stellate fibres, and the muscse volitantes. It also explains why these ynuscce may be temporary or per- manent, trifling and fanciful, or very serious and organic. If the stellate arrangement results, as I beKeve it does, from the aggi-avation and attachment of the minute true pigment cells to the vessels, the least variation in this connection on the condition of the vessels may at once cause an irregular arrangement of the pigment cells, and impress the retina — for we must bear in mind that all images upon it ai'e micro- scopic. This impression may appear and disappear with the varying condition of the vessels, arising from disordered sto- mach or cerebral circulation, and be cured, as we know it constantly to be, by whatever corrects their condition; or the muscce may result from different organic changes in the choroid coat, which are incapable of being removed, and may indicate patches of effusion, or other structural lesions. In point of fact, we now know the important bearing which these dark specks have in our diagnosis of that important class of choroidal and retinal diseases which have been so generally confounded under the names of amaurosis and glaucoma. It also explains why these muscce may be constant in form in one case, and constantly changing in another; in the latter, a different loop of capillaries may be congested or con- tracted, or a morsel of fibrine may be deposited or absorbed ; in the former, the deposit may be organised, or the capillaries permanently altered.* Having already explained the anatomical relations of the cornea, and referred to its special characteristics as an accessory of no mean value in rendering vision more perfect and distinct by the form of its cm-ved surface, I pass on to the consideration of the aqueous humour, assisting to com- plete that most perfect of optical instruments, the eye. The * Organs of Vision, p. 174. CRYSTALLINE LENS. 57 simple nature of this structureless means of distending the greater portion of the globe is worthy of notice : in the first place, . it consists of little more than ten parts of some sahne and normal matter in one hundred parts of water. Its density has been determined to be somewhat less than that of the cornea, for the purpose, it is presumed, of render- ing achromatic the comj)ound lens the two form in combination. It is admirably adapted to facilitate the freest movement of the iris, and as readily admits of those focal oscillations of the crystalline lens, rendered more necessary by every alteration of form in the cornea ; for I have no doubt that, by the instrumentality of the ciliary processes, and the erectile function of the choroid system generally, the due adjustment of the wholes is effected (like corresponding parts by the adjusting screws in a microscope), so as to preserve a constant integrity of purpose in focusing upon the retina.* Of the crystalline lens, I have chiefly to remark upon the evidence its structure affords of the extent and character of its participation in the process of accommodation ; and here I differ considerably from recent continental observers, whose arguments, experiments, and cases in point, it seems the practice in England now to accept, with much too httle question of their worth or importance. A display of learned and industrious research is apt to invest with fictitious im- portance statements as to facts which, tested by an equally close inquiry, will not bear out the inferences that have been derived from them. N o better instance of this can be given than the discussion which has arisen upon the situation of the changes in the form of the refracting surfaces of the eye, to adjust it for near or distant objects. Upon this subject, volumes, I may say, have been written, to prove how small * It would be impossible to deny that the cornea undergoes considerable change both in form and curvature ; in conical cornea, for instance, we have the greatest degree of myopia produced, and the reverse in glaucoma from flattening. Between these two conditions, various modifications are produced by intra-ocular pressure. 58 CRYSTALLINE LENS. is the influence exerted by the curvature of the cornea, in which we know alterations, and abnormal phenomena in con- sequence, are constantly occurring, as if intended to demon- strate the importance of this part in the function of accom- modation ; whilst, on the contrary, the greatest stress is laid upon changes which, at the best, can only be assumed, not only on the anterior surface of the crystalline lens, but on the posterior surface, although this is so far embedded in the vitreous humour as, at all events, to preclude any experimen- tal observation upon which much reliance could be placed. For my o^vn part, I believe that, in the accommodation of the eye, the curvature of the crystalline body itself is unchanged, and that its movements depend upon the special organisms provided for this important purpose ; namely, the erectile tissue of the ciliary bodies, the ciliary muscle, and the reaction of its elastic suspensory ligament. I also conclude, from the peculiar character of the structure of the lens, admirably adapted as it is to obviate any incon- venience that would otherwise arise from spherical aberra- tion, or the differing foci of rays coming from a distant or from a near object, so that no interference of a secondary nature can be philosophically assumed to aiise which might tend to destroy, or at least suspend, this useful pro^•ision. We know that the crystalline lens possesses a gradually in- creasing density from its circumference to its centre, the former being represented by a refractive power of about 1-3767, the latter being increased to 1-3920. It is also evident that it contains some proportion of water ; and it is a fair inference that this difference in the density of the lens may be produced by some corresponding difference in the distribution of fluid throughout the varying thicknesses of its structural layers ; and these, arranged in segments, are again split up into the most delicate serrated fibres, as sho"\vn in Fig. 9, from its optical axis to its marginal edge. At all events, there is that in this delicate adjusting provision for exact sight which, above all, claims protection for any interruption of effect. If, however, we yield assent VITREOUS BODY. 59 to the advocates of those extensive changes occurring in the surfaces of the lens during the process of adjustment or accommodation, and that such changes are effected by pres- siu-e exerted ])y the suspensory ligament of tlie lens, we at once concede that this compensatory property in the struc- ture of the lens has no fixed value or law, but is subject to all the fluctuations incidental to the ever-changing require- meiits of vision. The vitreous body fills up and distends the posterior thi'ee-fourths, or even more, of the globe of the eye. The retina, as far as the ora serrata is superimposed upon its investing membrane, the hyaloid, the delicate tissue inter- vening, or, according to some authorities, amounting to an organic connection. This I have not been able to confirm ; though it is undeniable that the question is one that does not admit of easy determination, owing to the firm adhesion of the two membranes, and their extreme translucency. Of the gelatinous substance itself, opinion is equally conflicting as to its structure, and the character of the organisation which supports and nourishes it. The safest conclusion seems to be, that it is simply a collection of very delicately organised cells, containing a viscid fluid, the refractive power of which, accorded to Brewster, is about 1.3,394. Except in containing a larger proportion of albumen, it differs little in constitution from the aqueous humour. In my remarks on the nature of light, see page 21, I have de- scribed experiments which sufficiently prove that, besides its mechanical use in the construction of the eye, as the mere instrument or organ of seeing, the vitreous humour subserves what must be presumed to be an equally important purpose — that of excluding the heat rays, so as to preseiTe, under all circumstances of exposure, a uniform condition and effect upon the retina. How far the vitreous body is affected by those changes of form that must take place in the eye in the various processes of accommodation and adjustment, is to me a question of con- siderable interest. If the communication of the need is a 60 FUNCTIONAL ACCESSORIES matter connected with the dii'ection or amount of light re- ceived from the actual object examined — and there is no reason why this should not be the case — ^then, consistency to my opinion of the influence exerted in accommodation by the choroidal system generally, requires me to adhere to the view that, between the degrees of the greatest and the least ex- tremes of the operation referred to, corresponding extents of the special apparatus provided would only requii'e to be excited to the necessary amount of action. The absorption of light by the choroid coat, and its correlative parts, would thus constitute the measui'e, and it would evidently be the motor agent of the change in the form of the eye, and which, com- mencing in its fullest and most sensitive development the ii'is and ciliary body, would extend backwards until even the fundus, and consequently the whole \itreous body, must be- come subject to a pressure of increased turgidity in the vessels of the choroid coat itseK. This certainly would not tell upon the unyielding expansions of the sclerotic and the tendinous insertions of the intra-orbital muscles, but rather upon the less resisting vitreous body, producing an elonga- tion of the globe forwards, or that protrusion which chai'ac- terises the staring eye of the anxious or excited mind. In the analogy observable between the forms and rela- tive densities of the transparent humours which enter into the formation of the eye, the achromatic combination of lenses is too striking to be passed over in silence ; and we are irre- sistibly impressed with the conviction that the combination is made to be quite achromatic. The two menisci formed by the aqueous and vitreous humom-s ha^dng the double- convex crystalline placed between them of greater density than either, and the two former differing from each other in density, appear to fulfil the conditions of achromatism in a striking manner ; and it is doubtless to this combination that is due the freedom from colour in the image depicted on the retina. I think it necessary to observe that it is the opinion of Sir Da\'id Brewster that spherical al>er- ration is also corrected by the varying density of the crys- OF VISION. 61 talliiic Ions, wliicli, having a greater refractive power near its centre, refracts the central rays in each pencil to the same point as its circumferential rays. Functional Accessories in the Economy of Vision. The nerves of the cornea, and their peculiar reticular distribution, I have already described ; and it is only neces- sary to observe fm^ther of them here, that they are generally said to proceed from the long ciliary nerves derived from the third pair. My own observations, however, lead me to the conclusion that they are filaments belonging to the first division of the fifth pair, a nerve of ordinary sensation, uniting with others received from the sympathetic plexus. The character of the distribution of the third pair of nerves in the orbit, with branches of the fourth and sixth in addition, all being motor nerves, has attracted considerable attention, and which I cannot pass by without remarking upon the confirmation it affords of my view as to the general relaxing effort in all the other recti muscles of the eyeball, to give intensity of contracted power to the corresponding ones on either side, by which a consentaneous action and accord- ance in direction are secured in both eyes. It must be noticed that five out of the seven muscles within the orbit are supplied by the third pair, whilst the fourth and sixth pairs are each directed almost exclusively to individual muscles ; namely, the superior oblique and the external rectus. This special arrangement is evidently intended to subserve some economical purpose; for, all being motor nerves, no other reason but such as I have pointed out can well be imagined to account for the fact of the third pair of nerves not supplying the whole of the muscles of the eye, in strict analogy with other parts of the body, where one motor trunk is specially made the medium between the muscles and the brain. Considerable discussion has also arisen as to the real 62 FUNCTIONAL ACCESSORIES source of nervous irritability to the fibres of the ciliary muscle and iris, and much discordance exists between the various authorities who have written upon the subject. There is no doubt, the ciliary nerves derived from the third pair can be readily traced into the structure of the iris ; and as, in birds, where the ciliary muscle is largely developed, these nerves are found increased in size, analogy is strongly in favour of ascribing the peculiar movements of the iris also to their presence. Several investigators, however, have sought to prove that, whilst contraction might be due to the ciliary nerves, dilatation, on the contrary, was due to the influence of certain minute branches issuing from the superior cervical gangHon of the sympathetic, passing up into the cerebral plexus, and from thence to the lenticular ganghon, situated at the back part of the orbit. The experiments and illus- trations employed to establish this opinion appear to me insufficient, by conflicting with the simplicity of a much more natural explanation, based upon the positive presence of true motor filaments from the third pair, sufficient of itself to account for all the movements of the iris, if considered as a sphincter muscle of an exceptional, but not altogether of an involuntary character, since several cases are recorded of the evident influence of the will over the movements of the pupil. At all events, we know that the filaments which are derived from the sympathetic are insufficient to produce con- traction under circumstances where paralysis of the third pair has led to the completest dilatation of the pupil. In face of all these circumstances, the opinion alluded to is, I think, scarcely tenable. The most important of the accessories of the eye, and which has been admh-ably designed for the purposes of vision, is the retina. This was formerly regarded as only a simple expansion of the optic nerve. Histological anatomy has carried our knowledge considerably beyond this limited view of one of the most elaborate organisms of the body. Besides the special nervous elements of its structure, it exhibits, under the microscope, tissues peculiarly its own. Enume- OF VISION. 03 rated as tlicy can be discerned in a succession of examined objects — for it is impossible, in this most delicate texture, to follow U13 the observation of more than two of the several layers at once — the first, in close connection with the choroid coat, is the minute cylindrical bodies wliich constitute the membrane described by Dr. Jacob, and named after him. They are closely packed together, like the pile of a rich velvet, standing at right angles to the true fibrous expansion of the optic nerve, and accordingly perpendicularly in relation to the centre of the eye. Some observers describe a bulbous enlargement at both ends, which, however, I can only corro- borate with regard to their lower insertion or origin with their parent source. And I can scarcely understand these so-called rods or cylinders to be any thing else but the sen- sorial organs of vision, and allied in character to the much coarser development which mark the terminations of the gustatory nerve on the surface of the tongue — an analogy to which I shall direct more especial attention when I come to speak of certain functional disorders of the eye. Surround- ing the inner ends of these rods are observed numerous cy- lindrical bodies, which, with a much thicker and better- defined layer of granular elements that succeed them, I am inclined to think are intimately connected with the fully de- veloped rods, both in structure and use. As far as regards the cones, KoUiker certainly entertains a similar opinion; as he describes them as being rods with a conical inner extre- mity, instead of a filamentous one, such as he thinks marks the corresponding end of the true rod of Jacob's membrane. A vesicular layer is next distinguished, consisting of a grey cineritious cerebral substance, interesting chiefly as evidently determining the commencement of a distinct struc- ture, in which the first filaments of the fibrous layer of the optic nerve are definitely observed. The latter expansion is separated from the rods by the granular layer being partly imbedded in the vesicular one, from the cellular structure of which its specific character sufiiciently distinguishes it. Its inner surface is well marked by the distribution of the vas- 64 THE RETINA, cular layer, as it is called, which is supplied by the central artery of the retina, and disappears in a capillary form when- ever its vessels penetrate the vesicular and granular struc- ture. Last of all, interposed between the fibrous layer and the vitreous humour are the hyaloidal cells, which some ana- tomists contend belong to the fibrous layer, whilst others allege that they are to be considered as part of the hyaloid membrane — a matter of Little importance beyond attaining that exactness of determination which so honorably marks modern research in every thing connected with histology, and the structure of the eye in particular. Having thus briefly enumerated the various described layers into which the structure of the retina has been resolved, I desire to direct particular attention to the following inge- nious summary of the probable modus operandi by which rays of light proceeding from an object produce a sensation upon the retina, and convey a knowledge of its presence and cha- racter to the brain : " Instead of regarding the retina as composed of layers, however, we are now generally agreed in considering that the fibres of the optic nerve pass radially through the retina. Thus, from the fibres a thread passes downwards till it meets a cell of the vesicular layer ; this, in tiu'n, is in connection with a granule of the granular layer, which terminates in a cone and rod — these latter forming the real termination of the optic fibres on the pigment layer of the choroid coat. It is now held that the rods and cones are the percipients of Hght, which they communicate to the cells of the vesicular layer, thence to the optic fibres, and thence to the optic gang- lion. The point to be borne in mind, in this descrij)tion, is that the sensitive part of the retina is not the surface on which the light immediately falls, but the surface which is in contact mth the black pigment. " So that if we suppose an image to be formed on the retiaa, it ^n^U not be transmitted to the brain ; but it will excite the specific sensations of which the optic centre is alone capable, and these will be transmitted. But it ■\\ill be easy A TRANSPARENT MEDIUM. 65 to prove that no images can be formed on the surface of the retma. In the first place, the retina, during life and health, is as transparent as glass. The rays of light must therefore pass through it and enter the pigmental layer, which, being perfectly black, absorbs all the rays. Further, it has been proved that the optic fibres are totally insensible to light. There is the ' blind spot' where the optic nerve enters, and where nothing but nerve fibres exist. There is also a spot in each eye where the sensitiveness to light is at its max- imum; and this is a mass of cells, without a continuous surface layer of fibres. The especial part for the reception of light rays, out of which the necessary images are formed, Professor Draper maintains to be the pigment layer. To prove that this is the real optical screen on which the images are formed, he reminds us of Franklin's experiments, of placing variously-coloured pieces of cloth in the sunlight on the snow, and so arranged that the rays should fall on them equally. After a certain period, he examined them, and found that the black cloth had melted its way deeply into the snow, the yellow to a less depth, and the white scarcely at all. The conclusion which he drew has since been abun- dantly confirmed : namely — that surfaces become warm in exact proportion to the depth of their tint ; because the darker the surface, the greater the amount of rays absorbed. A dark surface, absorbing all the rays, becomes the hottest. This principle Professor Draper invokes in his examination of the eye ; and he insists ' that the argument against the retina being the screen on which images are formed, is, both optical and anatomical, perfectly unanswerable. During life, it is a transparent medium, as incapable of receiving an image as a sheet of clear glass, or the atmospheric air itself; and its sensory surface is its exterior one : this is the one nearest the choroid coat. But the black pigment, from its perfect opacity, not only completely absorbs the rays of light, turning them, if such a phrase may be used, into heat, no matter how faintly that may be, but also discharges the well- knoAvn duty of darkening the interior of the eye. Perfection 66 THEORY OF VISION. of vision requires that the images should form on a mathema- tical superfices, and not in the midst of a transparent medium. The black pigment satisfies that condition ; the retina does not. " If the retina is insensible to the light which passes through it, it will be ecjually insensible to the light which is reflected from the pigment layer. On the other hand, al- though the pigment layer is capable of absorbing light, we cannot suppose it also sensitive to light. Hoav then is the luminous sensation produced? Professor Draper furnishes an answer to this : — ' The primary effect of the rays of light upon the black pigment is to slightly augment its tempera- ture, and this to a degree which is in relation to their inten- sity and intrinsic colour — light which is of a yellow tint exerting the most energetic action ; and rays which corre- spond to the extreme red and extreme violet, the feeblest. The varied images of external objects, which are thus painted upon the black pigment, raise its temperature on becoming extinguished, and that in the order of their brilliancy and colour. In tins heal disturbance of temperature tJie act of vision commences ; this doctrine being in perfect harmony with the anatomical structui'e of the retina, the posterior sui-face of which is its sensory surface, and not the anterior, as it ought to be, if the explanation usually given of the nature of vision is correct ; and therefore, when we pass the tip of the finger over the surface of bodies, and recognize cold and warm spaces thereupon, the same process occurs, with infinitely more de- licacy, in the eye. The club-shaped pai-ticles of Jacob's membrane are truly tactile organs, which communicate to the sensory surface of the retina the condition of tempera- ture of the black pigment. Professor Draper's experiments satisfactorily prove that all photographic efiects result from an increase of temperature. ' The imjDinging of a ray of light on a point, raises the temperatui-e of that point to the same degi'ee as that possessed by the soui'ce from which the ray comes ; but an immediate descent takes place through conduction to the neighboimng particles. This conducted A PHOTOGRAPHIC EFFECT. 67 heat, by reason of its indefinitely lower intensity, ceases to have any chemical ejfiect ; and hence photographic images are perfectly sharp on their edges. It may be demonstrated that the same thing takes place in vision ; and in this respect it may almost be said that vision is a photographic effect, the receiving surface being a mathematical superfices, acting under the preceding condition. All objects will therefore be definite and sharply defined upon it ; nor can there be any thing Kke lateral spreading. If vision took place in the retina as a receiving medium, all objects would be nebulous on the edges.* " To explain the process by which the change of tempera- ture in the pigment becomes a luminous sensation will not be difficult, if — remembering that the luminous sensation is not one depending on the specific stimulus of light, but on the specific nature of the optic centre — we follow this change in its passage from the pigment to the rods and cones of Jacob's membrane, which it affects. These are in direct connection with the ganglionic nerve-cells, in which we sup- pose the nervous impression to be excited ; this impression is thence transmitted, by means of the optic fibres, to the optic ganglion, and hence it becomes a sensation. Funke has a good illustration of this. ' The wave of light,' he says, * can no more excite the optic nerve diredhj, than the pres- sure of a finger upon the air, or the walls of the organ-pipe can excite musical notes. The finger produces a tone by pressing on the keys : each particular key that is pressed brings forth a corresponding tone as the air enters the pipe. * The photographic process, it has been said, is a true analogue of the physical part of vision. The prepared plate is called sensitive ; so too the ex- pansion of the optic nerve within the eye is like it. Mr. Gi'ove has shown that light falling on a plate prepared for photography, will set up a galvanic current. Does not this also suggest itself as an illustration of the process of vision ? Light impinging on the retina determines therein a chemical change, which develops in the optic nerve the nervous force. This force sets up in the brain an action of the same order as that in the retina. Hence, again, originates a nervous force, which, conveyed back to the eye, sets up yet, a third time, a change (in the iris) which causes contraction of the pupil. F 2 68 NATURAL ILLUSTRATION OF VISION. In this illustration, the optic fibres are as the organ-pipes ; the rods and cones of Jacob's membrane, as the keys ; and the waves of light, as the air. But the most convincing ar- gument against the retina as the receiving screen of images, and in favour of the pigmental layer, is, in my opinion, to be found in the eyes of the invertebrata. In the eye of the cephalopoda, this portion of the pigment has long been a puzzle ; and Professor Owen says that it must doubtless be ' performed by the retinal papillae ; or otherwise a perception of light must take place in a manner incompatible with oui* knowledge of the ordinary mode in which the retina is affected by luminous rays.' " In the crab's eye, the pigment layer covers the retina ; in the blind Crustacea, no pigment is j)resent ; and in albinos, in whom the pigment is deficient in colouring matter, the vision is very imperfect. In the nudibranchs, vision is simply the perception of light and darkness. The changes of tem- perature produced by the absorption of the rays in their pigment cannot be elevated into the perception of an image, because the optical conditions for the formation of an image are absent. An indefinite sensation, resulting from a change of temperature, is all that they can perceive. Nay, even were their eyes so constructed as to form optical images, there is little doubt that vision, in our human sense, would still fail them, owing to the absence of the necessary combi- nation of tactile sensations with sensations of light. We see very much by the aid of our fingers. If we remember that, according to the hypothesis, light only affects the retina after changing the temperature of the pigment, which change is communicated to the rods and cones, and thence to the vesi- cular layer, there will be nothing irreconcileable in the inverse arrangement of the retina in the invertebrata; in both, the process is essentially the same ; and mere differ- ence of position is not more than the difference of the chain of ganglia, which in the vertebrata is dorsal, and in the in- vertebrata is ventral."* * Quarterly Review. ACCOMMODATION AND ADJUSTMENT. 69 Consideratiom connected with the Mutual Accommodation and Adjustment of the Eyes. The theory of the accommodation of the eye in adapting itself to meet all contingencies of situation and size in visible objects, so necessary to perfect vision, has been, and may continue to be, a very unsatisfactory arena of learned dis- cussion. As usual, however, I shall endeavour to avoid all useless and laborious disquisition where our knowledge of facts is, at present, too limited to admit of plain and sen- sible explanation. One thing is evident enough — that the eye does possess this power of accommodation ; and whether it be effected by influences acting upon the movements of the iris, or by alterations produced in the curved surfaces of the cornea and crystalline lens, or whether, by altering the rela- tive position of the lens and retina by muscular action exerted upon the former, or by shortening and elongating the axis of the eye by pressure affecting the contained humours, or, lastly, whether it be by the concurrent operation of all these assignable causes, every one must feel assured that the old doctrine entertained by such men as Haller, Magendie, and others equally eminent, that the eye does not possess any power of accommodating itself to different distances, is utterly untenable. How this is done, and so far as this important function of the eye is to be considered in relation to the proper use of the ophthalmoscope, I shall endeavour to explain according to my own views, being, in a measure, compelled to take this course ; for, as a recent writer justly remarks, " no investi- gation has given rise to so much speculation, to more expe- riments, or to a greater number of learned calculations, with less satisfactory result for the labour bestowed, than this enquiry." In the first place, it is necessary to observe that the position of the eye in the orbit is sustained by an equilibrium of common action in the direct muscles of the eye-ball, and 70 ACCOMMODATION AND ADJUSTMENT which, for all purposes of attentive observation — that is, for fixing and steadying the eye in direct vision — act as one. This function of combined effort is apt to be overlooked, though it really constitutes the great difference of condition between the eye-ball out of action, asleep, reposing on its soft cushion of adipose tissue, and its waking, watchful duty, to let no knowledge escape that conies within its province and power to communicate to the brain. This does not preclude an independent specific action in each separate muscle, which indeed is predicated by theii^ several directions and distinct points of origin from around the optic foramen, and surround- ing the entrance of the optic nerve. The twofold object to be obtained is, the freest mobihty, with the steadiest and surest aim at will ; and, in my oi)mion, this is more easily reconciled with an arrangement of motor power, such as I have described, than by referring it to an inactive state of these muscles at all times, except when impulses of will communi- cate the motion desired ; illustrating the circumstances thus sought to be explained, by the case of a ball suspended in a fluid, and susceptible of motion in any and every direction — a most unfortunate analogy, inasmuch as it suggests nothing of that admirable steadiness of object attention, to secure which, is the chief pui'pose, I believe, of the rec^i-muscles of the eye-ball. It is more to the purpose to refer for illustra- tion rather to the nicely sustained equilibrium which keeps the body in an erect position by a counterpoising effort of the mutually antagonising intra- and supra-pelvic muscles of the lower extremity, and which, suddenly suspended — as, for example, where a momentary death occurs on the battle- field — so sufiiciently demonstrates by a prostrate form the effect of inactivity. Another most important consideration also leads to the conclusion of continuous action, being the normal state of these muscles. To prevent two imj)ressions being conveyed to the brain, by separate images upon the two retinae, looking at the same object, a perfectly consentaneous action is neces- sary in the muscles of both. An efiort of the will, however, OF VISION. 71 operating in different dii'cctions — for instance, in moving the abductors and adductors of the opposite eyes — under ordinary circumstances, implies a contradiction ; but the anomaly is obviated, and reason satisfied, by supposing that the re- quired result is obtained by a simultaneous relaxing of all the other muscles, excepting those required to direct the eyes on the oljject desired. But this adjustment of the two eyes, so that the retinae should convey true impressions of a single object to the brain, does not concern the ophthalmoscopist so much as a further provision for altering the focal length between the field of the retina and the dioptric media of the eye; and to explain which, and the organic economy employed to effect it, has led to the particular study of the accommodation of the sight for distant objects, and, in some degree, to the size also of objects looked at. Parallel rays falling upon a lens from a distant object, and divergent rays from a near one, vary considerably in their distances of focal length upon optical principles sufficiently well known. Some means are, therefore, proved, a jn-iori, to be necessary, to adapt the refractive media of the eye, accord- ing to circumstances, so that the focal images of objects, far or near, shall fall exactly upon the retina. And it follows, also necessarily, that a different conformation of the eye must take place in every adjustment for distinct vision at different distances. In the normal eye, it is evident that this accommodation is, in great part, an involuntary act, capable, however, of an impulsive increase of energy, as observed in the difference between ordinary attention to all and everything around, and the effort of more complete vision when required to examine a point, or scrutinize an object under the microscope. The aid even of other parts is sometimes called upon to assist : as, for example, when, for a distant object, the hand is used as a shade. Nor is it at all unusual for short-sighted people habitually to bring their eye-lids close together, so that by flattening the surface of the cornea, and by excluding useless 72 ACCOMMODATION AND ADJUSTMENT rays of light, they may thus obviate some of the inconve- niences of an abnormal condition of sight. If we examine the structure of the eye for the purpose of discovering the organic agency by which ordinary accommo- dation is effected, it is most essential to bear in mind the great difference that exists between certain special deviations from the normal standard of a healthy eye, and such as are occasioned by organic lesions and disorganisation, or are caused by mere functional disturbance. The former may be perfectly natural in an individual sense, as in the presbyopic and congenital myopic — the one being the necessary conse- quence of a gradual decHne in the powers of hfe, the other an obvious structural defect, with which pathology has nothing to do, save in a negative way to infer the condition in some true diseases of the eye, the symptoms of which correspond with defective appearances in myopia. At the same time, where so much doubt and obscurity exist as to the actual uses of each of the several adjusting accessories of the eye, it cannot be a sound philosophy that woxdd seek to estabhsh a theory upon the subject, by evidence derived from abnormal phenomena, which depend upon some change of structure, especially when so many illustrations exist in the history of medicine of the extraordinary adaptations of neighbouring parts to other than their own proper functions, which nature has resorted to, to compensate for deficiences, the result of accident or disease. The too frequent neglect of this great distinction in the circumstances of the two conditions of the eye has led to unsatisfactory discussions and contradic- tory conclusions, and at which I cannot but express some surprise, as there are sufficient evidences of the means em- ployed, to adjust the eye in perfect vision, to be found in the vital mechanism developed in the anatomical structure of this marvellous organ. Before we pass on to other considerations, it will perhaps be expected that I introduce a short summary of the con- clusions entertained upon the subject of accommodation by eminent continental ophthalmologists. OF VISION. 73 Since Kepler first ventured an opinion of the difficult question of how change is effected in the eye, it has constantly- occupied the attention of physicists and physiologists. At different times, an altered position of the lens, elongation of the anterio-posterior diameter of the eye, contraction of the pupil, change in the form of the lens, have been supposed to fui'nish a sufficient explanation, either separately or com- bined. The experiments of Cramer and Helmholtz on this subject seem to have resulted in the determination of the following changes as taking place in the eye during the pro- cess of accommodation for near objects. " 1. The pupil contracts. " 2. The pupillary margin of the iris moves forwards. " 3. The periphery of the iris is thrown backwards. " 4. The anterior surface of the lens becomes more convex, and its vertex passes more forwards. " 5. The posterior surface of the lens becomes also a little more convex, but does not perceptibly change its po- sition. The middle of the lens therefore becomes thicker." Accommodation for near objects is effected by increasing the curves of the two surfaces of the crystalline lens — ^. e. by diminishing their radii, the vertex of the posterior surface of the lens remains in situ, that of the anterior passes for- wards, and thus the space between the two becomes greater. Henke maintains that accommodation for distant objects is effected by contraction of the radial fibres of the ciliary muscle. The ligament of the lens, he observes, is relaxed when the radial fibres of the ciliary muscle are contracted, the circular fibres at the same time pressing on its equator. " Cramer concludes, from his experiments, that the in- creased convexity of the anterior surface of the lens is caused by the action of the iris, both circular and radial fibres being contracted at the same time, compressing the periphery of the lens, and thus pushing forwards the central portions. He also considers the use of the ciliary muscle only to be to prevent the lens passing backwards when compressed by the iris, and also to protect the retina. This was opposed by the 74 ACCOMMODATION AND ADJUSTMENT observation of Griife — that, in mydriasis, the power of accom- modation may be either lost or not. In the former case, the pupil may again become mobile, and yet the paralysis of accommodation continue ; or inversely, the pupil may re- main immoveable, and yet the power of accommodating the eye return. Szontagh, who has the power of voluntarily dilating the pupil, accommodated for his nearest point of distinct vision equally well with his pupil, varying from 3.9 to 7.1 m. m. in diameter. In him the accommodation is evidently independent of the size of the pupil. Ruete found good accommodation in a case of congenital absence of the iris ; and, finally, a case has been recorded in which Grafe removed the whole of the iris, yet the accommodation re- mained almost normal. " The fact that it may continue normal in cases of con- genital or artificial coloboma of the iris, in anterior and pos- terior synechise, although worthy of consideration, was, per se, insufficient to prove the absence of any participation of the iris in the process. A. von Grafe hence concludes that not only the processes of accommodation, but also the action of atropine, are independent of the presence of the iris. " In both respects, the tensor choroideae must be the single active agent. As to the manner of action, no further deduction can be drawn from the position of the ciliary pro- cesses, than that exact contiguity to the equator of the lens is not necessary. Bonders endeavoured to explain the ac- cojnmodation by the conjoined action of the iris and ciliary muscle. He was the first to assign an imj)ortant j)art to the ciliary muscle — that of forming a fixed point for the action of the radial fibres of the iris : he also referred a certain amount to the action of the ii'is. Helmholtz believed that the zonula Zinnii, when tense, flattened the lens, and that it became relaxed by contraction of the ciliary muscle. Heinrich Miiller distinguished two sets of muscular fibres in the ciliary muscle, external or radial, springing from the inner wall of Schlemm's canal, and passing outwards and baclavards, to be inserted into both sclerotic and choroid, OF VISION. 75 and internal or circular, running parallel with the corneal margin, and principally situated in the anterio-internal part of the muscle, near the insertion of the iris. Miiller con- siders that the circular fibres, when contracted, must exer- cise pressure on the ciliary processes, ciliary margin of the iris, and thus on the margin of the lens, and that the longi- tudinal (radial) fibres caused increased pressure on the vitre- ous body. The posterior surface of the lens is thus impeded from passing backwards, and the effect of the pressure exer- cised on its margin is essentially limited to the anterior surface. These changes he considered to be favored by the iris and zonula Zinnii. Mannhardt holds that the posterior insertion of the muscle forms the fixed point, towards which it draws the anterior portion. He does not deny, however, that the posterior part is also carried a little forwards. According to him, the ciliary muscle is probably the single causa movens of the mechanism of accommodation, causing a difference in the hydrostatic pressure in the anterior and posterior parts of the eye. The change in the form of the lens is effected by a tension and altered direction of the zonula Zinnii — the very opposite of the view generally adopted by other German authorities, who consider the tensor cho- roidese, or ciliary muscle, the principal active agent." * Dr. Pilz, in connection with this subject, makes the following remarks : " Every eye has, in accordance with the structure of its optic media, a certain refractive power. Consequently, the spot on which the image of any object is produced on the retina can only remain the same when the object is a certain distance from the eye. With a change of the latter, the image assumes a different position, falling in front of the retina when the object is removed further from the eye, or behind it when the object is placed nearer to the eye. In such cases, instead of a distinct image of the object viewed, diffused rays would strike the retina, and vision would be * Modico-Cbirurgical Review, 1862. 76 ACCOMMODATION AND ADJUSTMENT extremely imperfect, did the eye not possess the power of bringing rays from objects at diiferent distances to a focus at one particular point, which power chiefly depends on the refracting apparatus." Doubtless the examination of a body, whether far or near, requires a conscious effort to direct and determine the line of vision of the eyes in two converging lines, severally terminating at the object point examined. This essential preliminary to perfect vision is provided for by the consenta- neous action of the intra- orbital muscles, as I have before mentioned ; but it is accompanied also with a more occult and a perfectly involuntary excitation in the transparent media of the eye itseK, the object of which is to adjust the dioptric apparatus, so as to secure, under all cu'cumstances, the proper focusing of rays of light, coming from sources either far or near, upon the retina. From first principles, we might naturally suppose some such power to exist; for if a lens concentrate parallel rays into a focus, at a certain distance behind it, let the object approach so near that the rays are diverging, the focus will then recede further from the lens — a phenomenon which increases as the object is brought nearer stni. As a first step in the investigation of the movement necessary to obviate the effect of this law of optics, and adapt the eye to all situations, Olbers very wisely calculated the amount of difference in the focal lengths for distant and near objects, as deduced from the refractive powers of the media of the human eye ; and he found the change in distance of the retina from the lens required for vision at all distances, supposing the cornea and lens to maintain the same form, w^ould not exceed more than one line, which he considered might be effected by an elongation of the eye, or by a change in the position of the lens. I have already advanced an opi- nion myself as to the probable means employed in altering the focal adjustment of the crystalline lens, so as to allow perfect images of near or distant objects to come to a proper focus upon the retina ; and I may add, that several trustworthy au- thorities — such as Porterfield, Camper, and others — main- OF VISION. 77 tained corresponding views of the direct functional influence, for this important purpose, possessed by the ciliary pro- cesses and muscle. Strengthened in my conviction by such names as these, I think it unnecessary to extend the discussion further on the modus operandi of adjustment — than which, few other sub- jects connected with human physiology have excited more controversy with so little practical results. It is different with regard to the extent of the changes in the internal eye necessary for distinct vision at different distances ; for this is a matter so capable of satisfactory demonstration by indi- vidual experiment, that it is only requisite for me to direct attention to certain rules of observation, by which uniformity of expression and a standard method are secured, for the general information and advantage of surgeons, patients, and manufacturing opticians who supply the necessary glasses. It is observed that the eye, when most at rest, is adapted for a certain distance, usually called the most distant point of distinct vision; and rays of light proceeding from an object at this distance come to a focus exactly upon the retina. By exerting a certain power, we are likewise able to see with distinctness objects placed much nearer, which is a positive act of accommodation, in which the media of the eye have so changed their relative position that the diverging rays in this latter case are also brought to focus accurately on the retina, instead of in some point of a Hne (more or less, according to the position of the object being examined) behind that membrane. In short, there is in every eye a limit, nearer than which an object cannot be brought without its becoming indistinct ; and this is called the nearest point of distinct vision. Another limit is also given by the range of the eye when at rest, and this is called the furthest point of distinct vision. Throughout a space between these two, the normal eye is enabled to see distinctly, and with uncon- scious effort. As the age of man increases, however, it is found that the refractive powers of the eye diminish, and a series of changes 78 ACCOMMODATION AND ADJUSTMENT take place, the result of wliicli is, that the power of accom- modating vision to near objects is gi-adually lost. Even before such changes can be discovered, the ophthahnoscope shows that the media become less transparent as years ad- vance — a fact especially noticeable in comparison with the beautifully clear fundus oculi of the child, although the power of accommodation is much earher diminished than that of refraction, the position of the more distant point of distinct vision long remaining the same, whilst that of the nearest point becomes gradually further and further removed from the eye. In fact, the change in the refracting powers of the eye are usually observed only in very advanced age, when a convex glass becomes necessary for seeing distant objects distinctly. It is generally considered that, in healthy, youthful sub- jects, eyes of natural conformation will read with distitictness at the distance of fifteen or sixteen inches. Ten inches, however, is the distance of easy ordinary vision, as in reading or examining objects attentively. Beyond this it is usual also to describe a presumed limit to distant sight, further than which effective vision cannot be usefully directed ; though it appears to me no arbitrary maximum can properly be al- leged. Providing objects are visible at all — or, as Griife expresses it iu these words, " of infinite distance" — and with sufficient Light to be reflected, parallel rays from any distance can be brought to a focus on the retina, with particular effect, as distinguished from the general picture of external nature, the spontaneous presence of which on the retina defines its sensorial function, and describes vision in the abstract. The nearest point of distinct vision varies in different subjects, from four to seven or eight inches ; but on this part of the subject of accommodation I need say no more here, as the question relates entirely to healthy eyes. It is very different with regard to the consideration of abnormal deviations from the standard of natural vision, where, from some defect or malformation in the structural apparatus of the eyes, imperfect or indistinct images of ex- FOR DISTANT VISIOX. 79 ternal objects are producod upon the sensitive field of vision. It is generally some unusual or anomalous circumstance, connected, more or less, with a defective accommodation, that first awakens suspicion in the patient's mind of the pre- sence of some evil threatening his sight ; and to learn the extent of which, as determined by a practical test, is a pri- mary object with the surgeon, to measure the progress which the disease has already made, and mark the unit from which to judge of future changes. For this purpose, several little instruments, usually called optometers, have been invented ; the credit of the first suggested being due to our own country- man, Porterfield. The characteristic self-dependance and ingenuity of continental ophthalmologists have led to several modifications ; but, as a general conclusion, it may be said that all have proved failures, owing chiefly to the conditions of the examination not being favorable, even in the case of healthy eyes, to the exercise of the natural powers of accommodation, and must therefore produce fallacious results where abnormal sight is concerned. At the utmost, they can only show some of the distances for which the eye can accommo- date itself; but not the limits of nearest and furthest points of uninfluenced distinct vision. The consequence has been that reliance is now placed almost altogether upon what are termed type -tests. A conveniently graduated one, on the same principle as that suggested by Jager, is constantly used at the Royal Westminster Ophthalmic Hospital, and a copy of which is readily obtainable through any medical publisher. There are few cases of disease, and these are confined to the crystalline lens, in which resort is useful to the ordinary op- tometer of opticians employed in selecting spectacles, where the use of a convex or other lens is ingeniously conjoined with a graduated scale, so as to indicate accurately and con- veniently, by corresponding values, the powers of the glasses required to suit individual sight. The chief objection against the general use of lenses in measuring the extent of accom- modation, is that they almost always magnify the object, when the nearest point of distinct vision is being ascertained ; 80 TEST EXPERIMENTS. and the consequence is, that a reliable conclusion, under such circumstances, cannot he attained, as the measured space will, after all, not reiDresent the true natural one. The best way to proceed, in examining a case, is first to determine how near and how far off the smallest type in the test page can be distinctly read with the unaided eye, and in ordinary daylight. The next point of importance is to deter- mine, not so much the greatest distance of perfect vision, as the actual lineal extent of visual range, and which may be found by submitting, at a distance of about eighteen feet, the largest type used in the test page. If this is perfectly legible, it is evident that the eye receives and can accommodate itself to parallel rays — the question of chief importance involved in the determination of the most distant point, regarded merely as an aid in diagnosing presumed disease in the accessories of vision, or the condition of the refracting media of the eye. Degrees of power will also be evident, character- ising different cases, and accompanying the several stages, whether of progress or of rehef. Although I have, so far, carefully restricted myself to the absolute need of eyes in some stage of disease, and be- yond which examinations to determine the powers of accom- modation would avail very little, it is necessary that con- genital deviations from the normal standard of healthy eyes should be always carefully attended to, as they generally indicate a morbid disposition in the parts, and must have a proportionately corresponding effect in modifying the appear- ances observed in the ophthalmoscope ; and in illustration of which, I have already alluded to the characteristic non- requirement of a lens when examining myopic eyes ; and the necessity, on the other hand, of using one where the crys- talline, by operation or accident, has been removed. Donders, to whom is due the credit of classifying eyes into a natural system, at once simple and convenient, distin- guishes — firstly, normal or emmetropic eyes, in which parallel rays are focused by a natural effort upon the retina, and possess the power of accommodation, without diificulty, for CLASSIFICATION OF EYES. 81 divergent rays coming from objects six or eight inches from the eye ; secondly, myopic eyes, where the principal focus (that is, for parallel rays) fall before or in front of the retina : thirdly, hypermetropic eyes, the principal focns of which lies behind the retina. To this last belongs ordinary preshyopiuy which, although merely a limitation of the range of accom- modation due to the decKning powers of life, is still a con- dition which requires artificial means to obviate the inconve- nience that accompanies it, and therefore may justly be considered as within the province of ophthalmic surgei-y. Myopia is referred either to a too high refractive power in the transparent media, or to the optic axis of the eye being too long, the refractive power remaining normal. The principal focus, or that produced by parallel rays, falls there- fore in front of the retina, upon which circles of disper- sion produce an indistinctness, as if a halo surrounded the images. Divergent rays coming from near objects, however, focus on the retina, and are distinctly seen. Hypermetropia is a nearly opposite condition to that which is the case in myopia, or short-sight, as it arises rather from the refractive power of the media being too low, or the optic axis too short, the effect being to throw the focal point behind the retina, so that convergent rays only are united upon the retina. Both conditions of myopia and hyperme- tropia are attributable to a want of the power of accommo- dation altogether; or, what is more probable, to original weakness of this muscular act, leading to the use of instru- mental aid for relief, which ultimately accustom the eye to the new optical conditions they involve, and hence perpetuate the evil, until, as age advances, the natural change in the eye which marks presbyopia, or long sight, in some cases affords opportunity for spontaneous relief. A strong proof that the power of adjustment is easily subverted, is given by the fact that myopia may be acquired by employing the eye constantly for the perception of near objects ; as in close reading, and neglecting distant vision — a difference which marks the discipline of a college or a barracks with corrc- a 82 CONGENITAL MYOPIA, sponcling results, in the need for spectacles between the two different classes of young men concerned. But, after all the protracted discussion that has arisen upon the modus operandi of accommodation, I may perhaps he allowed to observe, that, at all events, as regards the use of spectacles, they do not really correct any defect in the functions of the ciliary muscle, or other quasi-mechanical accessory of adjustment, hut simply compensate for some defect in the refractive media of the eye. Thus the want of the crystalline is supplemented by strong convex glasses ; and between tliis extreme case and the shghtest deviation from the natural curvature of a healthy lens, desiderates spectacles of every corresponding degree of power, to com- pensate for the failing powers of vision ; and this Avithout admitting any question to arise as to the condition of the accommodating powers of the cihary muscle to meet the cir- cumstances of near or distant sight ; for as yet I have not heai'd of any artificial optical means which are in the least sufficient to remedy the temj)orary distui'bance of vision, at all distances, which arises in the every-day experiment of paralysing that muscle by the use of atropine or belladonna. We are seldom consulted for congenital myopia ; neverthe- less, in all cases care should be early taken, in young per- sons, to correct it, by proper advice and suitable spectacles. Some slight decrease may certainly be expected as age ad- vances. Donders is incliued to dispute this, although he himself admits that by the increased diminution of the pupil such eyes frequently do see better at a distance as they grow older. Other remai'ks of this eminent oculist upon that always very serious circumstance, progressive myopia, are much more important, and deserve to be quoted in his own words. " During youth, every myopia is, perhaps, more or less progressive ; the progi^ess of the affection is then accompanied by symptoms of ii'ritation, which, according to Von Grafe, may even assume the character of sclerotico-choroiditis pos- terior. This is the critical period for the myopic eye : if the ITS PREVENTION. 83 Inyopia does not at the same time increase too much, it may remain stationary ; or, at a more advanced age, even decrease. If, however, it becomes greatly developed, we shall find it almost impossible hereafter to arrest its progress. At this stage, we must therefore avoid every thing that may cause determination of blood to the eye, and thereby tend to in- crease, not only the sclerotico-choroiditis, but also the tension within the eye. I cannot lay too much stress upon this. Every progressing myopia is threatening to the eye. If it remains progressive, the eye will soon become less and less usable (troublesome symptoms at the same time showing themselves), and not unfrequently vision is irrevocably lost at the age of fifty or sixty (if not sooner), through de- tachment of the retina, extravasation, or atrophy and dege- neration of the yellow spot." * The practical commentary upon the above extract that naturally suggests itself, is the care and caution necessary to prevent young people, threatened with myopia, from engaging in pursuits calculated to develop the affection, or greatly to exaggerate the evil if already present. It is about the age of puberty that the first symptoms are most apt to appear ; and accordingly the close application of the eyes, at that period, to studies, or to write a continued or too fine a cha- racter, is clearly contraindicated. Any occupation that exercises the accommodation of the eye to very short dis- tances, as watchmaking, fine engraving, &c. after a time imposes a permanent condition undoubtedly myopic, as the power, in one eye at least, to unite parallel rays, under ordi- nary cu'cumstances, upon the retina is lost. Varying degrees, in either eye, of this defect, are also frequently observed pro- ducing corresponding degrees of indistinctness with which either eye, at the same distance, can distinguish the lines of printed characters on a plane surface from each other ; and in selecting spectacles it is important to keep this fact in view, as many cases of impaired vision complained of are, * Von Griife, Arcliiv, vol. vi, 2. 220. G 2 84 CHOICE OF SPECTACLES when investigcated, characterized by this iiTegularity of focal coincidence on the retina3. Patients are too apt, indeed, to neglect the eye that is most near-sighted until it becomes quite useless in looking at any near object ; that is to say, the image fonned in that eye is not perceived, unless atten- tion is particularly directed to it. A more disagreeable effect is when spontaneous efforts to overcome the irregularity in- duce strabismus — a symptom which, on its first appearance, should suggest an immediate examination of the condition of the eyes in this respect, which, admitting of an effectual re- medy by providing proper glasses, becomes, by delay or neglect, not only a permanent disfigurement, but a soiu'ce of much discomfort, in the impaired vision that always accom- panies it. Such cases frequently come under observation. Lately I was called upon to divide the internal recti muscles in a young lady, myopic from childhood, where amblyopia to the extent of complete loss of sight in one eye, had arisen from the strabismus ; and the operation, by restoring the natural correspondency between the axes of the two eyes, was followed by the further satisfactory result of perfect vision being again shared in by both. " Now all practitioners are agreed as to the advisability of allowing myopic persons spectacles for the purpose of seeing distant objects. For we thus change theu' eyes into normal ones, and enable them to unite parallel rays upon the retina. We should, however, prescribe the weakest glass with Avhicli the patient can see clearly and distinctly at a distance, so that he may only make use of a minimum of his power of accommodation, and not have to strain it un- duly when observing near objects. For we must remember that he will but seldom have to look for any length of time at a distance, but will alternately observe near and distant objects. Now, if the glasses are too strong, he is already obliged to use more than a minimum of his power of accom- modation when observing distant objects, and will conse- quently have to make use of a still greater amount (perhaps almost the whole) when looking at things but a short IN MYOPIA. 85 -clistanco from him. His myopia will therefore soon in- crease. " There can also be no harm in allowing short-sighted persons glasses for the purpose of seeing things at the dis- tance of a few feet (e. ^. playing the piano, &c.). But the •patient may also desire spectacles for reading, writing, &c. Donders thinks that, although it is advisable to give myopic persons at first weaker glasses for reading than for distant objects, we should at a later period, if their range of accom- modation be good, give them (even for reading) spectacles which completely neutralise their myopia. " It is still, however, a much-debated question whether short-sighted persons should be allowed glasses for reading, &c. Donders strongly recommends it (except in exceptional cases), for the following reasons: — 1. Because strong con- vergence of the optic axes is necessarily accompanied with tension of accommodation. The latter is an associated action, not arising from the mechanism of the convergence, but existing within the eye itself, and may consequently easily lead to an increase of the myopia. Besides this, the pressure of the muscles upon the eyeball appears to be greater when the optic axes are convergent than when they are parallel ; and this increase of pressure cannot but tend to give rise to the development of posterior staphyloma. 2. On account of the habit which short-sighted persons have of bending their heads forwards during reading or writing. This must cause an increased flow of blood to the eye, and an increased ten- sion within the eye itself. Owing to this, the development of sclerotico-choroiditis posterior, effusions of blood, and detach- ment of the retina, which are so apt to occur in short-sighted persons, are undoubtedly greatly promoted. For this reason, we should always tell these patients to read with their head well thrown back, and to write at a sloping desk. " But it may, on the other hand, be ui-ged that it is just in looking at near objects that myopic persons have an ad- vantage ; for they can see them remarkably distinctly. And the great danger is, that after reading for a short time with 86 CHOICE OF SPECTACLES spectacles, the patient, on getting somewhat fatigued, will, instead of laying the book aside, approach it nearer to the eye, in order to gain greater retinal images, and thus strain and tax his power of accommodation too much. If we, for in- stance, give a patient, whose far point lies at eight inches, a pair of spectacles which enable him to read at twelve inches, he will, if not very careful, after a short time almost insen- sibly bring the book nearer to his eyes, and thus have to make use of a greater amount of accommodation. If he does this frequently, he will soon increase his myopia. The greater the range of accommodation, the less harm will spec- tacles do, and vice versa." " The presbyopic patient (who is generally above forty years of age) complains that his sight, particularly in the evening, is beginning to fail him for near objects, small print, &c. At a distance, however, he can see perfectly. In order to see minute objects more distinctly, he removes them farther from the eye, or even, perhaps, seeks a bright light, so as to diminish the circles of dispersion upon the retina by narrowing the area of the pupil. But as, on ac- count of the distance at which these fine objects are held, their retinal images are very small, he will soon experience a commensurate difficulty in clearly distinguishing them, and feel the want of spectacles. " In true presbyopia, the far point is at a normal distance from the eye, parallel rays are united upon the retina, and neither concave nor convex glasses (even after the applica- tion of atropine) at all improve distant vision. The eye is neither myopic nor hypermetropic. There is, in fact, no anomaly of refraction, but only a narrowing of the range of accommodation ; the near point is removed too far from the eye, and hence the difficulty of accurately distinguishing small objects. " Presbyopia is, however, often accompanied by amblyopia (weakness of sight), and the latter is sometimes mistaken for it ; this may the more easily occur, as the amblyopic patient also cannot see small objects distinctly, and as convex glasses I IN PRESBYOPIA. 87 improve his vision by affording him larger retinal images. In a purely presbyopic eye (which is free from amblyopia) we should, by means of the proper convex glass, be able to restore a normal sharpness of vision and a normal range of accommodation. With this glass, the patient should be able to read No. 1 of the type- tests at a distance of about 12 inches. If he cannot do this, but only perhaps decipher Nos. 4 or 6, or if he is obliged to hold the object very near his eye (nearer than is warranted by its size), he is not only far- sighted, but also amblyopic. It may therefore be laid down as a practical rule that the nearer we can approximate, by means of convex glasses, the vision and range of accommoda- tion of a presbyopic eye to that of a normal one, the less is the impairment of sight due to amblyopia, and vice versa. " Donders has found that in the normal (emmetropic) eye the near point gradually recedes, even from an early age, further and further from the eye ; and that, in consequence of this, vision for very minute objects becomes proportionately more and more difficult. This recession of the near point commences already about the tenth year, and progresses regularly with increasing age. At forty, it lies at about eight inches from the eye ; at fifty, at eleven or twelve inches ; and so on. In the normal eye, no inconvenience or annoyance is experienced from this recession till about the age of forty or forty-five. This change in the position of the near point is met with in all eyes — the emmetropic, the hypermetropic, and the myopic (if the latter remains healthy). "There can be no question as to the advisability and necessity of affording far-sighted persons the use of spectacles. They should be furnished with them as soon as they are in the slightest degree annoyed or inconvenienced by the pres- byopia. Some medical men think that presbyopic patients should do without spectacles as long as possible, for fear the eye should, even at an early period, get so used to them as soon to find them indispensable. This is, however, an error ; for if such persons are permitted to work without glasses, we observe that the presbyopia soon increases. 88 PRESBYOPIA. " The proper glasses for the presbyopic may be readily calculated. A convex glass of sixteen inches focus will bring the near point back again to eight inches from the eye. We must generally, however, give somewhat weaker glasses ; be- cause, on account of the greater convergence of the optic axes, the near point will, through these glasses (convex 16), be in reality brought nearer than eight inches. Late in life, when there is some diminution in vision, Bonders thinks that the near point should sometimes be brought even to six or seven inches, and that it should be brought the nearer, the greater the range of accommodation. " He further thinks that when no hypermetropia exists, the weakest glasses with which No. 1 of the type-tests can be distinctly and easily read at about twelve inches distance, may generally be given. " In choosing spectacles for far-sighted persons, we must also be particularly guided by the range of their power of accommodation. If this is good, we may give them glasses which bring their near point to eight inches ; but if it is much diminished, weaker glasses should be chosen, so that it may lie at ten or twelve inches from the eye. " It must be borne in mind that a very rapid increase of presbyopia is one of the premonitory symptoms of glaucoma. If, therefore, a patient tells us that his far-sightedness has rapidly increased within a few months, so that he has had re- peatedly to change his spectacles during that time for stronger and stronger ones, our suspicions should be aroused, and we should without fail examine him as_^to the presence of other premonitory symptoms of glaucoma, — e.g. rainbows around the candle, periodical obscurations, &c. Von Griife thinks that this rapid increase of presbyopia is most likely due to an increase of intra-ocular presssure."* * S. Wells, ' Medical Times and Gazette,* 1861. 89 CHAPTER IV. OBJECTIVE AND SUBJECTIVE EXAMINATION OP THE EYE. OPH- THALMOSCOPIC APPEARANCES IN HEALTH. OPHTHALMOSCOPIC APPEARANCES IN DISEASE. In all investigations connected with diseased conditions of the eye, as in other parts of the body, it is obvious that the evidence obtained is marked by two very different principles directing opinion : one depending upon the surgeon's sense of what he observes himself; the other on what the patient may choose to tell him. The terms objective and subjec- tive, to describe symptoms so relatively distinguished, are here a convenient and suitable employment of these not un- frequently misapplied words. It may therefore be as well to state that I class aU evidence as subjective which depends upon the patient's statements and the general history of the case ; and on the other hand, all as objective which has re- sulted from direct examination, and for the value of which I depend upon my own judgment and experience. The practical importance of some such distinction is evi- dent ; for whilst the objective is, or ought to be, positive knowledge, subjective evidence is apt to be very uncertain. Personal feeling, or local sensibility, is sometimes greatly exaggerated, or, on the other hand, depressed or altogether suspended, from circumstances of constitutional or diseased conditions in the individual ; and it therefore requires to be especially remembered that investigations made with the view of ascertaining the sensibility of the eyes to external 90 OBJECTIVE AND SUBJECTIVE influences, have only a relative value, depending upon the state of the nervous system of the patient generally. In its normal state, the conjunctiva is not very sensitive to an ordinary touch with the finger, whilst, on the contrary, to sudden or extreme changes of warmth or cold it proves extremely sensitive. If either be long continued, it inva- riably produces pain. Tears and nervous twitchings of the eyes are also readily excited by the extraordinary sensitive- ness of the reflex functions of the nerve supply, which carries intelligence to the sensorium of the presence of some foreign or hostile body on the surface of this membrane. The du'ect sense of positive feeling is equally strong over its palpabral extension, as the two points of a pair of com- passes scarcely the eighth of an inch apart are easily dis- tinguishable ; although, when applied to the tarsal margins, the poiuts require to be carried considerably wider apart, even to the extent of eight or ten lines. The conjunctiva nearest to the inner and outer angle of the eye is very sen- sitive, and the points of the compass may be still more closely approximated, yet still produce a distinctly recognized im- pression. A corresponding sensibility to degrees of heat and cold also marks the several parts of this structure. Very great importance attaches to the amount of tension of the coats, and in the globe of the eye, recognizable by the practised touch of an experienced surgeon. Considerable deviations from the normal state are observed to take place under different circumstances of disease. Inflammation is always accompanied with more or less hardness and tension, produced by an increased secretion of the humoui's, both aqueous and vitreous. On the other hand, these symptoms diminish Avith the progress of the inflammatory process ; as when it passes into suppuration, or, more happily, disappears with corresponding reabsorption of the secretion in excess. But, besides increased fulness in the vessels, or of effused fluids within the eye, owing to idiopathic disease, or resulting from accident, a multitude of symj)tomatic, otherwise sym- pathetic, causes ai'ise to interfere with normal functions and EXAMINATION OF THE EYE. 91 produce a similar turgid condition, or the reverse, in the globe — an observation which is intended to include all the different forms and degrees of distension due to what is described, in general, but very vague terms, as glaucomatous tension. It is most essential, therefore, whenever the eye in disease appears to be of an abnormal fulness, that the degree of tension and hardness should be immediately ascertained, and a care- ful examination made, firstly of the state of the sclerotic coat, its colour, together with the degree of perception of light ; the activity and appearance of the iris should then be observed, and, as far as possible, of the ciliary vessels, which, in every internal disease of the eye, materially affect the circulation, by interfering with the collateral supply of blood, and are the most probable seat of the disturbance, or otherwise its active cause. The advocates for iridectomy, indeed, seem to rely chiefly on the direct reduction of this influence for the success of the operation ; as they allege that the excision of a vascular portion of the iris diminishes the secreting sur- face of the distending fluid. The mode of examination by pressure of the fingers requires- that the patient should close his eyes as if asleep. Both fore- fingers should then be applied upon the upper lids, pressing a little upon them at the same time. Being satisfied in this way that augmented tension does exist — to estimate the degree, it is necessary to place the forefinger of one hand upon the inner or nasal side of the globe, and the other forefinger upon the outer side ; then gently compressing with one finger whilst the eye is steadied by the other, two or three times repeated, and alternately from side to side, a sufficient estimate of any undue hardness or tension is thus easily obtained. A compa- rison of the condition of the two eyes, made in the same manner, is always a useful proceeding. A further objective examination of the conjunctiva, and the general appearance of the external coats of the eye, will also aid us considerably in forming an opinion of the extent of the mischief. In this investigation, I request 92 OBJECTIVE AND SUBJECTIVE the patient to open the eye as wide as possible, and to look at me full in the face. The upper lid is then raised by placing the hand on the forehead and drawing it upwards Avith the thumb, whilst the lower can be retracted down- wards and pressed by the other hand upon the malar bone. This is also the simplest and best way of exposing the palpebral surface of the conjunctiva for the extraction of a foreign body. Children are generally very troublesome; and when photophobia is present, it is difficult to induce them even to open the eye. In such cases, there is no course, other than that of physical force, but to wait and try the effect of haK-grain doses of antimony to subdue the intolerance of light. And in examinations of this kind, where inflammation is present, it is as well to know that, besides the usual dis- tinction between the parallel lines that mark increased vascularity of the sclerotic from the irregular tortuous ar- rangement observed in a similarly affected conjunctiva, the colour of the former communicates a tinge of purplish crim- son to the otherwise brick-red hue of the latter. When photophobia exists, the objective examination of the eye is sometimes very difficult. In such a case, the pa- tient must be placed with his back to the light, or a fitting shade be employed. In this way rays of light may be thrown into the eye from above, and opportunity thus afforded to de- termine the character of the disease. In patients affiicted with cataract, where a suspicion exists that it is associated with disease of the retina, a strong light should be thrown into the eye with a lens or plane mirror ; and if no effect of its presence is produced, we may justly conclude the retina is. insensible, and that an operation would be of no avail. It is useful also to note the amount of subjective light which results to the patient from pressure of the finger upon the eyeball. In general, the circle of light, when produced, is of a perfect form ; and it has been observed that spasmodic contractions of the muscles of the eye give a similar pheno- menon. Also the blood which circulates in the retina and choroid may, when rapidly increased in quantity, be made EXAMINATION OF THE EYE. ^3 more apparent by mere pressure of tlie finger ; and it oYten occurs spontaneously after some violent mental and bodily excitement, or on partaking of an immoderate quantity of spirit or narcotic, or by coughing, sneezing, vomiting, &c. ; indeed, l)y every cause that produces a rapid flow of blood to the head. Such phenomena of light and colour are brighter and more intense when the eyes are closed, and in a darkened room ; because, in this instance, light and colour produced by pressure are increased by obscuring, or shutting out, the other parts of the field of vision. For the same reason, fever patients frequently see ocular spectra in the dim light, or when the eyes are closed. This phenomenon may be made of some diagnostic value, in cases of closed pupil, or certain kinds of cataract, to determine whether the retina is still active. If equal pressure be made upon the globe, and no light or circles of fire appear to the mental vision of the patient, then the sensibility of the retina is certainly lost, and no operation could be expected to restore sight. With the same object in view, it has been proposed to employ electricity ; but as the effect produced by this, will at the same time affect the brain, and excite a sensation of light there when the retina is already completely paralysed, this experiment must often mislead. Nevertheless, it may be often used as a remedial agent ; and it is worthy of remark, as I have assui'ed myself by direct experiment, that the form and colour pro- duced differ, as we apply either the positive, or negative pole of the battery, to the closed eyelid. If it be necessary to examine the condition of the lachry- mal gland, an apparently more formidable manipulation of the eye is demanded. The upper lid is draAvn as gently as possible from the globe ; the extremity of the little finger is then inserted, with the nail laid next or upon the sur- face of the eye, and pressed obliquely upwards and out- wards, when the substance of the gland will be immedi- ately felt. In the healthy state, it appears to the touch like a smooth hard mass, about the size of a small bean. If it varies much in size, in figure, or in hardness, taken in 94 OBJECTIVE EXAMINATION connection with the history of the case, any such condition may be regarded as indicative of disease. The iris, so prominently and actively engaged in vision, is always to be carefully examined objectively, whenever disease has invaded the globe. Its sensibility, mobility, size and shape, are all to be particularly noted, as affording not only evidence of its own normal or abnormal condition, but many indica- tions of great value in determining that of other parts of the eye with which it is connected by a very characteristic ner- vous sympathy. Its natural movements, in fact, depend upon the health and integrity of the retina, and the trans- iucency of the optic media. Under ordinary circumstances, the healthy iris is per- fectly circular, the pupillary diameter varying a great deal, even in health ; in youth, it is observed to be larger than in adult age. During contraction, it always comes a little forward; but where there is exudation within the vitre- ous chamber, or any increase in the vitreous body, or in the capsule of the lens, it is pressed outwards very con- siderably. On the contrary, any corresponding diminution, as where the crystalline lens has been removed, the usually plane surface of the iris becomes concave. The movements of the iris are all involuntary, and due to a reflex action, rather than to direct nervous sensibility. Trom this cause, contraction can be induced by irritation of sensitive nerves more or less distant, as is instanced in the application of cold to the pituitary membrane of the nose, or to the surface of the conjunctiva. And it would seem that this reflex action is regulated by the degree of excitement to which the retina is exposed ; for the greater the power of the light, the more decided is the contraction of the pupil. The reverse condition corroborates this conclusion ; for, in para- lysis of the retina, though the action of the third pair of nerves is quite unimpaired, the pupil continues immove- ably dilated under the most powerful irritation of light. In sleep, however, it must be observed, it is considerably dimi- nished in size, even when amaurotic disease is present. OF THE IRIS. 95 This reflex action is well illustrated by the sympathetic correspondence of the pupil of the protected eye with the movements experimentally excited in the other. It is also seen in cases of monocular amblyopia, where the pupil of the dis- eased eye may be made to contract and dilate with that of the healthy eye. By carefully watching this consentaneous and synchronous effect, we may often obtain some useful objective evidence. It is necessary, however, to take proper precautions ; such as causing the patient to look at an object placed before him at the ordinary distance of distinct vision, so that nothing may impede the action of the light upon the retina, and thus unfairly interfere with the reflex movement of the iris. First one eye should be opened and examined, then the other, afterwards both together — each time noting the con- dition of the pupils. If found to move uniformly, it is a proof at least that there is no paralysis of the motor nerves of the iris ; though, as before mentioned, there may be present com- plete insensibility of the retina in one eye. Again — if, when opening alternately one eye and then the other, we find that, whilst one is shut, the exposed pupil is immoveable or fixed, it is evident that the retina of this eye is paralysed or insen- sible. Somewhat the same means may be taken to ascertain the condition of the ciliary nerves, and whether their paralysis is co-existent with that of the retina. The change of accommo- dation of vision for near or for distant sight is indicated by a corresponding movement in the iris : the pupil contracts when a near object is examined, and dilates when looking at another far off. Holding up a finger, therefore, before one eye whilst the other is closed, and bringing it gradually nearer, the changes produced in the size of the pupil examined, give a tolerably accurate account of the powers of its presiding motor nerves. If neither dilatation nor contraction take place, the inference of paralysis may still, however, be wrong, and the examination should therefore extend to the form and con- dition of the pupil, to ascertain whether it retains its circular appearance, or is somewhat irregular in outline. In the 96 OBJECTIVE EXAMINATION latter case, its immoveability may arise from adhesions around its margin, amounting to mechanical obstruction; for when the iris is attacked by inflammation, the exuded blood plasma rapidly changes colour, and cobweb-like fibrillse are thrown out, securing, as it were, the muscular fibres to- gether, and filling up the interstices ordinarily observed. As atrophy of the iris also sometimes supervenes, in consequence of the absorption of the proper tissue and the substitution of an adventitious material, of course immobility may be accounted for in this manner. In making examinations in cases of synechia, it is always necessary to use atropine or belladonna : should any dilatation take place, it shows there is only partial obstruction from the adhesions. The iris, however, may be perfectly regular in form, yet spasmodically contracted, the result of cerebral irritation ; as when it follows the early stages of poisoning by opium, or in severe cases of tabes dorsalis. It has also been observed attendant upon the presence of tumors in the cervical region, pressing upon the cervical branch of the sympathetic. On the other hand, an equally fixed and dilated pupil is a common indication of some organic disease in the brain. It is pre- sent also when extreme intra-ocular pressure seems to para- lyse the retina; and under some circumstances of spinal disease, due, it is supposed, to irritation of the great sympa- thetic, extending to the cervical ganglion, filaments from which preside over the dilatation of the pupil. A sluggish or inactive state of the pupil is always to be considered as measuring corresponding degrees of irritation in these so derived nerves, and should always excite suspicion of some generally disturbing influence in the system. The objective examination of the iris is not complete without noting its colour, the appearance of its vessels, their normal or abnormal condition, and whether any difi'erence is observed in the two eyes. In inflammation, the colour of the iris immediately changes : a blue iris becomes green ; a grey one, sometimes a light green ; a dark brown assumes a reddish-brown tint ; and a light brown, a ycllowish-bro^ra. OF THE IRIS. 97 These shades are also modified according to the scat of the inflammatory action ; for, if deeply situated, the pupillary margin presents a darker hue; if more superficial, the efi'usion upon which the change of colour depends is of a paler character, and spreads itself uniformly as a thin coat of colour all over the iris. In health, the comparatively thick walls and the pigment beneath effectually conceal the blood-vessels of the iris ; but when examined with a magnifying glass, they are plainly dis- cernible, appearing like fine white threads. Should hypercemia occur, the fibrous wall dilates, and the blood-vessels may then be readily seen at the pupillary margin, as a zone of delicate fringe, no doubt connected in some way with that peculiar retiform arrangement of the muscular fibres of the iris that form its pupillary margin. Not unfrequently we see a single vessel branching out over the anterior surface of the iris, and expanding into a close network of capillaries around its ciliary margin. In some congenital and abnormal states of the eye, a peculiar oscillating or undulatory movement of the iris may be observed, which is generally due to some disor- ganization in the vitreous humour, as in syncliysis. It also accompanies dislocation of the lens, and consequent loss of its suspensory ligament. As a practical point, and one of some internist, I would call attention to the changes which take place in the iris during the inhalation of chloroform. In the first stage, whilst the pulse rises, and the muscular system is excited to rigidity, the pupil contracts ; as insensibility gradually becomes more profound, although the pulse then sinks and the muscles relax, the pupil still continues contracted, as in deep sleep, gradually dilating again as consciousness is restored. In examinations of the iris, the convex lens may be em- ployed, and the light should come from a window, so as to fall over the patient's nose. The surgeon, standing on the same side as that of the eye afiected, then raises the upper lid with the thumb, and holds the lens between the index and second finger of his left hand, whilst the right is em- ployed in depressing the lower lid. H 98 ACTION OF BELLADONNA The specific action of belladonna upon the iris, and the use made of it to dilate the pupil previously to an examina- tion of the internal eye with the ophthalmoscope, require a few remarks from me ; for, although the advantages to be derived are incontestable, the evils sometimes ensuing from its incautious employment should not be allowed to pass un- noticed, I have frequently seen a drop of a very weak solu- tion of atropine produce, in the healthy eye, a very large amount of congestion in the capillary vessels, more than suf- ficient to deceive the practised eye of the surgeon, and which might well be mistaken for a diseased condition. For some time, therefore, my practice has been tending towards its •discontinuance as a general apphcation ; and I have found that, in a vast number of cases, simply allowing patients to remain for a short time in a room somewhat duller than the light of the day, has been sufficient to cause all necessary dilatation of the pupil. Besides, it is well that practitioners should be aware that, to act, the atropine must be absorbed ; and it then exerts a paralysing effect upon the nerves dis- tributed to the ii'is, as well as on the cihary muscle ; and the consequence is, the power of accommodation remains seriously affected for several days, and patients are very apt to complain of the annoyance. If, also, the sight from this time should become worse, the great probability is, that the surgeon will be blamed, as having caused some aggravation of the disease. To account for the dilatation of the pupil by the action of the salts of belladonna, very many experimental investiga- tions have "been made to discover the particular nervous track of the specific effect produced. Accordmgly, Dr. E. Waller, with Professor Budge, have made experiments which seem to prove that the nerve fibres of the cervical sympathetic which go to the iris origmate from the spinal cord, between the sixth cervical and the fourth dorsal vertebrae. And Dr. BroAvn Sequard has also ascertained that the origin of the fibres of the sympathetic going to the iris are still more ex- tended. He has shown that section of the spinal cord, as ON THE IMS. 99 high as the level of the fifth cervical, or as low as the ninth or tenth dorsal vertebra, allows the uncontrolled third cere- bral nerve to contract the iris. In agreement witli Bifti, Cramer, and Ruiter, Budge found that, after section of the sympathetic in the neck, and even after extirpation of the superior cervical ganglion, belladonna still exerts its dilating influence on the pupil, though in a less degree. Dr. Harley noticed that, after section of the sympathetic in the neck, by continuing the application of the atropia, the pupil becomes at last fully dilated. " If belladonna acted merely by paralysing the sphincter, we could not have such a result as this ; seeing that the dilator, already so completely paralysed by section of its nerve, would not be in a condition to act spontaneously on the cessation of the antagonism of the sphincter. The result, however, is consistent with the opinion that belladonna ex- cites the dilator pupillse, if we admit that the drug comes by absorption to act on that muscle. The result is also not inconsistent with the supposition that belladonna acts both by paralysing the sphincter and exciting the dilator. Budge has cut both the oculo-motor nerve and the sympathetic; nay, more — he has cut all the ciliary nerves, together with the optic ; and still found the pupil to dilate distinctly under the influence of atropia. This result is entirely consistent with the opinion that belladonna acts both by paralysing the sphincter and exciting the dilator pupilla?." * To reconcile conclusions so opposite appears impos- sible. The natural inference is, that, in whatever way bella- donna acts in dilating the pupil, it is not through a medium so indifferently affected by the most serious lesions as are, evidently, the motor communicants of the iris with the brain and spinal column. It seems to me far more analogical to surmise that it is the nerve of sensation itself which becomes partially paralysed by the absorption of the active principle of the belladonna, and, in consequence, is less sensible to * Professor Wharton Jones. — ' Medico-Chirurgical Review.' H 2 100 OPHTHALMOSCOPIC APPEARANCES the stimulus of light ; an ejffect of suiTounding darkness is produced, and the then comparatively uninfluenced ciliaiy nerves of the iris dilate the pupil in accordance with their natural function. In the face of Budge's crucial experiment, where every motor and sensitive nerve connected with the economy of vision was divided, we must rather conclude that such is the case, or that the contraction of the muscular fihres of the iris is a power per se, to the proper exercise of which, belladonna is specifically antagonistic. Experiments in another direction have also proceeded on observations made of the presumed conflicting action of opium and belladonna; but little more has been proved, in my opinion, than what was previously well known to the pro- fession. The fact that opium and morphia produce contrac- tion of the pupil has always been remarked as the ordinary symptom of their therapeutic operation upon the brain, pro- ducing spasmodic constriction of a muscular sphincter, and as if in immediate subjection to an over-sensitive retina, impa- tient of light ; the reverse, in fact, of the condition of the optic nerve when affected by belladonna. To some extent, the specific effect of this latter, mydriatic, might counteract the local symptom produced by opium, without, however, having the slightest influence upon the primary remote cause of irritation on the brain, and would be a very empiiical proceeding. Strong coffee would have a much more legiti- mate effect. But truly the investigation promises no j)ractical benefit in ophthalmic disease ; and it is a question with me, whether the decided improvement in some forms of ophthal- mia, due to the specific action of opium, reducing local spasm by diminishing the sensibiUty of the vessels affected, be not really analogous to that which influences the motions of the iris after the application of belladonna ? Ophthalmoscopic Appearances of Healthy Structures. In examinations with the ophthalmoscope, the direction of the rays of light passing from the concave surface of the OF UEALTHY STRUCTURES. 101 mirror into the eye of the ijatient, though most important for the purposes of ilhimination, do not concern us so much as the reflected rays coming back from the fundus oculi, and which describe the images of their object source on the retina of the observer. The theory is, that the fundus sends back from each illuminated point a divergent cone of rays, which pass out at the same angles of refraction, and in the same plane of reflection to that in which they entered the eye, presenting an exact picture of its condition and appear- ance when examined with the ophthalmoscope. The fundus of a healthy eye is generally described as of a warm orange or pinkish red colour, owing to the rays of light being chiefly reflected from vascular tissues, more particularly from the capillary vessels of the choroid. The colour, how- ever, varies sometimes from perfectly natural causes, such as the quantity of choroidal pigment, or the greater transparency of the retina. If, also, the latter is well illuminated, or when the focus falls exactly upon it, it may be perceived as extend- ing of a light grey or blueish grey over the bright choroid beneath. If, therefore, with normal vision the retina appears somewhat opaque or cloudy, it must not be considered due to a pathological change in structure, but to some constitutional peculiarity, producing a physiological phenomenon. The bright red of the choroid coat is also modified by the amount of pigment ; where it is less than usual, the lighter is the colour, and the brighter and warmer is the red ; where it is more, it imparts a yellowish red or brownish tint to the whole of the internal eye. It is to be observed also, that the pigmental colour of the ii'is is some guide ; for we find that with a brown iris the fundus is of a darker red and more florid than when it is blue. In young persons also, and in the delicately pale, the fundus Avill be found of a brighter and more vivid red than in older and more robust persons. " If we trace the course of the Light sent from the ophthalmo- scope after it has passed through the refracting media, it must be observed that it first meets with the retina, which, being smooth and transparent, reflects but little Ught, cither 102 OPHTHAJiMOSCOPIC APPEARANCES regularly or irregularly, when the light falls nearly horizon- tally on its surface, as it must of necessity do. It next reaches the layer of hexagonal pigment-cells, covering the choroid internally, when a considerable proportion is absorbed, some is transmitted, and a good deal seems to be reflected. The transmitted light arrives at the choroidal vessels in the next place, and some is reflected, some transmitted, and some absorbed. The pigment in the interstices between them will, if strongly developed, absorb most of the light which falls upon it ; but some may be transmitted tlu'ough both it and the vessels and the sclerotic, which has a great reflecting power. The hght returning from these more deeply-seated parts suffers loss from absorption in passing again through the more superficial ones ; and it is also dispersed by them in such a way that it rather tends to affect the colour of the latter and the apparent brilhancy of the image which we see, than to give us a definite perception of the form and colour of the objects from which it is reflected. The less strongly developed the superficial pigment is, the less absorption and dispersion will take place."* Considerable discussion has taken place as to the differ- ent influences exerted upon light by the several membranes which enter into the structure of the fundus oculi. Rather, how- ever, than engage in any such unsatisfactory inquiry, I have preferred to give the above quotation from the writings of one who has studied the subject. To return to the appearance of the fundus in the ophthalmoscope — in the centre of the observer's field of vision, looking somewhat dowuAvards and inwards, is seen the optic nerve entrance, its colour being slightly or greyish white, and nearly circular in shape. Sometimes, however, it approaches an oval form, and may have even an irregular outline. The arteria centralis retina, -mth. its accompanying vein, pierces the optic nerve and enters the globe through the porus opticus. It immediately divides into four or five branches, which at first run between the hyaloid * Rainy, op. cit. OF HEALTHY STRUCTURES. 103 membrane and the nervous layer of the retina, then entering the hitter membrane, forms a close capillary network in its substance ; at the ora serrata, terminating in a single vessel which bounds the margin of the retina. The vems which begin at the ora serrata by an incomplete circle, run with their trunks parallel to the arteries, and collect in the vena centralis which leaves the eye by the side of the artery. Of the two principal arterial branches, with their corresponding veins, one pair runs upwards and outwards, the other down- wards and outwards, surrounding in their course the macula lutea, yellow spot of Soemmering, which is free from all but capillary vessels. We sometimes find a considerable deviation in their distribution ; but at all times the arteries may b& easily distinguished by their brighter colour and more defined outline, which is attributable to the greater reflecting power of the arterial coats. The observer will also frequently see, indeed may always, by a slight adjustment of the lens, the pigmental interspaces between the choroidal vessels, appearing like stripes of a dusky brown colour. They are most easily seen at the circumference of the fundus oculi, and in the eyes, of persons of fair complexion."^ The facility afforded by the ophthalmoscope to examine the appearances of the fundus oculi is well illustrated in the instance of the visible pulse in the blood-vessels of the optic disc. The interest of the phenomena is also greatly increased by being sometimes observed in both the arteries and the veins ; but, as far as I am able to judge, only exceptionally and under conditions of an abnormal character. Coccius remarks that he could only observe it where some interfer- ence took place in tlie intra-orbital cuxulation, such as may be produced by pressing the eyeball with the finger ; and his explanation is evidently based upon the circumstance. " The retina is placed within a closed elastic capsule. When moved by the heart's systole, and consequently at the general dias- tole of all the arteries entering the globe, a pressure is * See fig. 1, coloured plate; 104 THE VISIBLE PULSE exerted upon the ocular capsule. The sum of this pressure must show itself chiefly in those places which soonest yield to the pressure ; and inasmuch as these (the sooner yielding parts) are the vessels which convey away the blood — the veins — an increasing pressure must be exerted upon them during the common diastole of all the arteries which enter the globe; and consequently they must be narrowed, and made to empty the blood more quickly." On this subject, however, as usual, the curious spirit of controversy, and con- flicting views, that characterize all German observations, quite obscure the facts. Immediately on the expression of this opinion by Coccius, it was opposed by a new observer, Dr. Ed. Jager, whose investigations were duly rewarded by the discovery of an arterial pulse, which had not been noticed previously. He considered that the idea of the blood being extruded from the veins with a laborious effort, by the addi- tional external pressure beyond that of the ordinary arterial diastole, gives rise to this extraordinary pulse, — is opposed to the fact that the veins empty their blood in a retrograde course from the centre towards the circumference of the optic disc, and refill, of course, in the opposite dii-ection. And, besides, Jager insists upon a rising and falling movement being clearly seen, distinct from the pulse, in that part of the vein which lies perpendicular to the optic disc — a phenome- non, which, at all events, I think may be faii'ly attributed to the increased tension and the consequent cumulative efforts of all the vessels of the eyeball to assist in overcoming the difficulty, and relieving an oppressed and laboured cii'culation. We find, again, that Von Grafe questions the correctness of Jager's observations, especially with regard to the visible blood movement, which the latter would restrict to those veins imbedded in the nerve substance, or which are spread over the inner surface of the optic disc. Von Griife con- siders the pulse is confined to veins which are completely enclosed in the nerve tissue; and Donders, an excellent authority, has corroborated this, by showing, in actual sections, that even the larger vessels projected on the surface OF TUE RETINAL VESSELS.' 105 of the optic disc are covered by a delicate layer of nerve fibres. Amidst all the discussion, however, that has arisen with regard to this matter, a useful practical conclusion may be drawn from the circumstance, that, in this pulsation of the veins and arteries of the eyeball, we have a very delicate metre of inter-ocular pressure, when j)roduced by some in- ternal abnormal cause, and the presence of which, without such evidence, might be unsuspected and readily overlooked. A natural effort of this kind, endeavouring to overcome simple congestion in many of the tissues, is no doubt sufficient to produce this visible movement; and accordingly it admits, by degrees of perceptibility, of being made some criterion to judge of the success or otherwise of any externally applied means of relief. I must confess to be far from satisfied with the explanations offered by the several German writers upon the subject to account for the phenomenon. The presence of pulsation in the veins I consider to be due entirely to the communicated movements from the closely associated arteries ; and the observation of Coccius, correcting Von Trigt on this point, confirms my view ; as he clearly proves that the ar- terial systole is synchronous with the venous diastole, exhi- biting no difference from the ordinary appearance of the general circulation ; which must be inferred, however, if an independent pulsatory movement be ascribed to the veins of the optic disc. The circumstance of the venous pulsation being discovered by Von Trigt some time previously to the arterial, and its very questionable existence at all, except when produced abnormally, or as a symptom of actual disease, suggests its probable dependance upon the very natural cause I have pointed out, and which is sufficient, without resort to any theory, to account for this interesting phenomenon in the pathology of eye-disease. Before an estimate can be formed of the pathological changes revealed by the ophthalmoscope, it must be endent that the normal picture presented by the back-ground of the eye demands careful study ; and the part borne by the difier- 106 OPHTHALMOSCOPIC ent membranes in the production of this picture ought to be made the subject of particular consideration. Great difficulty will at first be experienced, especially in the appreciation of a depression or a prominence, which depends in part on the alterations produced in the light and shade of inverted images, when a convex lens is used with the perforated mirror. In the examination of objects lying behind the crystalline lens, it must also be borne in mind that we are looking through that body, and consequently what is seen is magnified very considerably. Then, again, by using a magnifying-glass to examine the changes in the retina, or increase the illumina- tion in the interior of the eye, allowance must be made for- differences of intensity, as well as the size of the picture pre- sented. Before we pass on to other investigations and considera- tions, we must in all cases bear in mind : — 1st. That the crystalline lens reverses the parts on the concavity round the entrance of the optic nerve (placing the yellow spot on the nasal side, &c.). 2nd. That only a limited space round the optic nerve (its radius not extending so far as the yellow spot) is open to accurate examination ; and that the choroid forms one uninterrupted red field. 3rd. That the yellow spot is nearest that part of the optic nerve entrance freest from vessels, and which admits of the greatest number of optic nerve fibres being seen. Cfeneral Principles upon which to distinguish the Seat of Morbid Changes in the internal Eye. A PEW preliminary observations upon the morbid changes that take place in the inter- ocular media and tissues will be very useful, for the purpose of preparing the student for those deviations from the normal condition he is most likely to meet with in examinations -with the ophthalmoscope, and which must be duly considered and allowed for. Tui'bidity of the humours, for instance, in various diseased states of APPEARANCE IN DISEASE. 107 the eye, besides obscuring a view of the fundus, may consider- ably impair the transparency of the retina. On the other hand, some changes of an inflammatory nature much increase its reflecting power, thereby producing only a slight misty indistinctness in the appearances. The optic nerve entrance piercing the choroid or vascular coat of the eye may be veiy considerably affected by disease, with very little apparent change appearing on its disc. One condition of the papilla optica produces a singular effect, owing, no doubt, to some parts reflecting more light than others, and which Liebreich points out as being due to a dis- tribution of lights and shadows, as in the representation of a well-executed sphere on a plane surface ; so that, although the f)apilla does not normally present a globular form, in the ophthalmoscope it sometimes appears to do so. In glau- coma, where the optic nerve entrance is cupped or excavated, when examined with a convex lens this appearance becomes very striking ; for another optical illusion, depending upon the complete inversion of the image, so alters its natural cha- racter, that it appears as a raised, instead of a depressed, surface. " The most important optical deception," writes Dr. Mac- kenzie,* " which arises from viewing the fundus in the indi- rect method, as well as the most puzzling to a beginner, affects the papilla. The student has probably heard that the papilla, in the glaucomatous eye, is cupped or excavated ; but to his view it appears quite the reverse. It appears rounded and prominent. " To comprehend clearly that this is an illusion, aU that * 0. H. Reports, April 1860. I gladly make this quotation from the published writings of the Nestor of Eye-Surgery ; because I well remember the effect a letter of his produced on the Fellows of the Medical Society of London, before whom I brought my first paper on the Value of the Opbthul- moscopo. Mr. Haynes Waltou, having exhausted his own arguments against the use of the instrument, took from bis pocket a letter from Dr. Mackenzie, which appeared to support his view of the question. I am therefore par- ticularly gratified to find Dr. Mackenzie bearing testimony ta the great value of this instrument. 108 OPTICAL DECEPTION one requires to do, is to impress, with the head of a pin, a small dimple on a bit of paper, and put this under a com- pound microscope, with the concaye side of the impression uppermost. The same appearance will then he seen, which is presented by the papilla of the glaucomatous eye — namely, that of a rounded and protuberant surface. " This optical deception arises from the inversion which the image suffers from being viewed through the compound microscope. We judge that an object, viewed Avith a single eye, is convex or concave, solely by the manner in which light is reflected from the body under examination. The light vdiich falls obliquely on a convex sui'face illuminates that side which is nearer to the source of light ; the side farther from it is in shade. The light Avhich falls obhquely on a concave sui'face illuminates that side which is farther from the source of light ; the side nearer it is in shade. Let the source of light remain in the same position, but invert the image of the object illuminated, so that the light which falls on the farther side of it may seem to fall on the near side, which is the case when we look through the compound microscope at the hollow on a bit of paper, or when we examine the optic papilla through the compound microscope formed for the occasion by the patient's eye, plus the convex lens held in front of it ; and both the dimple on the paper and the papilla, although they are actually cupped or concave, will then appear convex and prominent. " If, on the other hand, we turn the convex side of the dimple on the paper uppermost, and view it with the com- pound microscope, it appears concave. The inversion of its image causes the light which falls on its near side to appear as if it fell on its farther side, and thus the eye is subjected to a deception the reverse of the former, and from which it cannot free itself. If there be cases, then, in which the end of the optic nerve within the eye actually projects in a con- vex form, they will offer, when examined in the mdirect method, the appearance of a cup or depression. " Such facts have long been familiarly known ; the appa- IN glaucoma: 109 rent transmutation of an intaglio into a cameo, or that of a cameo into an intaglio, under the compound microscope, being a common source of amusement, fully discussed by Sir David Brewster, in his ' Letters on Natural Magic, Letter V.' Important as theii" bearing is on pathological examinations of the eye, they seem to have escaped the notice of ophthal- moscopists, till attention was directed to the subject by Dr. A. Weber, in a paper in the ' Archiv fiir Ophthalmologic,' Band II, Abtheilung I, Seite 141." In a highly interesting communication in the same journal (Band IV, Abtheilung II, Seite I), Dr. H. Miiller has directed attention to the normal, as well as to several diseased, states of the optic papilla. " His account of the entrance of the optic nerve into the eye, and the diagram which he gives in illustration, accord remarkably with the thirteenth figure in Mr. Bowman's ' Lectures,' and the corresponding explanation. From the statement and figures of these two observers, especially those of Dr. Miiller, it may be gathered that the lamina cribrosa is normally somewhat concave towards the interior of the eye ; that the fibres of the optic nerve, suddenly losing their white substance and dark outline, enter the eye on a level with the chorio-capillaris ; that at this point the whole nerve, from the change which its fibres have just undergone, is con- siderably and rather suddenly reduced in thickness; that the fibres, bending more or less abruptly outwards, and spreading around, become clothed by the exterior or radially disposed layers of the retina ; that the edge of the opening through which the nerve passes into the eye, as well as the fibres themselves as they traverse that edge, form a slight elevation or approach to a papiUa, leaving in the situation where the trunks of the central vessels of the retina generally make their appearance, a small foveola. " Dr. Miiller points out the difficulties which attend the anatomical examination of tliis depression, arising from the softness of the part, and its liability to change on being touched ; and shows how these difficulties may best be 110 ABNORMAL APPEARANCE obviated. He directs attention to the varieties which exist in different individuals ; varieties in the depth of the de- pression, from 0-2 to 0*5 millimetre ; varieties in its form and position, for it is not always symmetrical, and does not always correspond to the middle of the nerve, but is some- times considerably nearer to the macula lutea, or has one portion of its edge more raised than the rest ; varieties in the disposition of the vessels, for while the large trunks ge- nerally emerge from the middle of the foveola, one or more sometimes seek a passage for themselves close to the edge of the chorio-capillaris, so as to make their appearance by the side of the nerve; facts, all of which should be carefully borne in mind by ophthalmoscopists. " In regard to abnormal prominence of the papilla, Dr. Miiller shows that this is likely to arise from an atro- phied state of the exterior layers of the retina, a thickened condition of the primitive nervous fibres, as well as infil- tration of the nerves by blood, inflammatory exudation, or new formations. He relates a case in which a concretion in the site of the lamina cribrosa caused a protuberance of the papilla. The very earliest stage of encephaloid tumour should show an abnormal prominence of the papilla. " On the other hand, intra-ocular pressure, and atrophy of the nerve, existing either singly or in combination, are the causes of abnormal excavation of the papilla. " Morbid excavation of the papilla varies in depth, reach- ing, in extreme cases, to a millimetre beyond the level of the choroid. In such cases, the sides of the excavation are nearly perpendicular, or are even concave, and its edge, of course, impendent, so as partially, or even comiDletely, to hide from view the course of the vessels as they pass from the bottom of the excavation and over its edge to the retina. In slight cases, the sides of the excavation are convex, and its form that of a funnel. The lamina cribrosa, under such circumstances, keeps its place ; but in more advanced stages, it is pushed back, and the excavation is much extended late- rally. Such extreme cases of expansion are not the result of OF THE PAPILLA. Ill unconi])ined atropliy of tlio nerve, but must arise from the supporting resistance of the parts being weakened by previous inflammation, whence they come to yield more readily to intra-ocular pressure." It should be kept in mind that the colour of even the normal papilla varies very considerably, being in some per- sons of a more innkish hue, than in others, where it resembles a grey cerebral substance. In several diseases, its vascula- rity is much increased, and small vessels, not perceptible on its usual pale ground, now come into view. In cases of congenital insensibility of the retina, the sur- face presents a greyish-white appearance, and in certain cases an entire absence of blood-vessels has been discovered. The gradual disappearance of the capillary branches of the retinal artery, especially on the inner side of the papilla, has been noticed, as marking the progress of a gradual loss of sight, dependant upon cerebral disorganization. An antemic or blanched condition (white atrophy) of this membrane is a very noticeable symptom of disease. Patches of serous exudation, the result of congestion, situated beneath the retina, are recognized by a bluish-white tint, sometimes scarcely perceptible, whilst in others it is very decidedly so ; and even vessels of new formation occur, the original ones being destroyed and lost. Some parts of the discoloured portions will appear almost or quite dark, owing to the^ light reflected not entering the eye of the observer. Any opacity in the crystalline lens, or other of the re- fractive media, with diminished power in the optic nerve, manifests itself with varying intensity. Sometimes the opacity is generally diffused, with thickening of the capsule ; or it may exhibit well-defined dark masses distributed throughout it ; and in othci's, fine delicate bands of fibrous material appear, adherent to the pupillary margin of the iris. In such cases, the bright yellowish red, or deep rose tint, of the choroid is lost ; and its colour, if seen at all, will be a hazy l)rown ; but as the disease progresses, it becomes at length quite indistinct. 112 ABNORMAL APPEARANCE If the trcansparency of the refractive media is only slightly impaired, the light reflected from the mirror Avill seem to move behind the nebulous opacity ; and if the pupil be fully dilated, and the light thrown in obliquely or laterally, with a biconvex lens, we can look as it were behind the opacity; and it will appear larger the nearer it is to the front of the eye. If, on the contrary, a concave lens is used, the object appears smaller the more it lies in front, and more magnified as its situation approaches the fundus. With the lateral movement of the eye, the shadow of the nebula describes a succession of angles of parallax with the optical axis. Those immediately in this line only, appear to be fixed ; but in all other situations they seem to move, as described, to the right or left of the line. Dark floating bodies, not unfrequently present in the vitreous body, may also be easily distinguished by this angular precession of their light shadows. It is different with a more diffused opacity in the vitreous humour, which may be confounded with opacity in the retina, or with a myopic condition of the eye, where an image of the light falls before the retina and produces a shadow. In the former case, however, the retina appears more or less distinct, or the opacity in the vitreous humour more or less decided, as recourse is had to the double test of a convex or concave lens, alternately employed in the examination. If the retina be really the seat of the opacity, the optic nerve entrance appears as if covered with a cloud or veil, and the central vessels as if seen through this cloud. A greater number and a more congested condition of the capillaries will be plainly distinguishable, especially over and around the papilla. The tortuous course of these vessels, and of the vena vorticosa of the choroid, assist in determining the character and situation of these pathological changes. With respect to opacities referrable to the media of the eye observed in the ophthalmoscope, the following general remarks will be found strictly applicable, and of very considerable diagnostic importance. " When we perceive OP THE REFRACTIVE MEDIA. 113 opaque bodies situated in the media by means of light coming from the fundus oculi, they will appear black, whatever their real colour may be : thus, opacities in the lens, though they may appear grey, or even wliite, under ordinary circum- stances, and contrasted with a black pupil, appear like black spots or streaks upon the illuminated fundus. We may, no doubt, see light reflected from the fundus oculi and light reflected from opaque bodies at the same time, and contrast will then determine, in a great measure, the appearances presented by the latter. Supposing an opacity in the lens to have a power of reflecting light falling almost perpendi- cularly upon it, equal to that of the fundus ocuH, the former would appear dark, in comparison with the latter, if the illu- minated area of the fundus were smaller than the area of the pupil ; because the fundus would, in that case, be better illuminated than the opacity, and the observer would in ge- neral see each with nearly its proper brilliancy, provided the pupil of the observed eye were somewhat larger than his own."* With regard to the opacities occurring in synchysis, or liquefaction of the vitreous humour, Grafe has the following remarks : " Diffuse or punctuated opacities of the vitreous merely throw a thin veil over the picture of the retina, obscuring the sharp outhne of the optic papilla and the retinal vessels. By more careful investigation, however, tliis veil will be found composed of a vast number of molecules, which are very difficult to discover, when they are situated, not in the same depth, but in difi'erent strata of the vitreous humour. In the first case, they constitute a finely sprinkled, semi-transparent membrane, which, alternately contracting and distending itself by dislocation of the component parts, moves like a net-work of delicate tissue before the back- ground of the eye ; if they are situated in difi'erent depths, the whole represents a fine dust or rain, which, during the move- ments of the eye, is often conglomerated into dense masses, * Kainy. Op. cit. 114 ABNORMAL APPEARANCES, and, on their cessation, sinks doAvnwards cither in an even mass, or in separate showers. The patients complain of a inist, shi"oucling external objects. These opacities disturb vision far more than larger but well-defined opacities, because in the latter case the intervening parts of the vitreous humour are perfectly transparent." The same obtains for diffuse, semi-opaque capacities of lens and cornea, where the Steno- psean spectacles of Donders have been found so valuable by- preventing the diffusion of light on the retina. As to the larger and denser opacities, they occur either as filaments or flakes. Opacities in the vitreous humour are often caused by exudation of lymph, and Ai'lt and Grafe describe cases where it was recognised by the ophthalmoscope anteriorly, proceed- ing, in all probability, from the ciliary processes. To recapitulate somewhat : — In all examinations of the internal eye, the natural florid red reflection from the fundus may be affected by the transparency of the media, the con- stitutional colour of the retina, and the quantity of choroidal pigment. The bright red of the choroid is always modified by this latter circumstance ; the less pigment, of course, the lighter and more vivid is its colour ; on the contrary, a great amount imparts a yellowish or brownish red tinge. I must also remark here, that the pigmental colour of the iris is no guide to that of the choroid ; for a bro"\vn iris is frequently associated with a fundus of a deeper and more vivid red than when it is blue. Age, too, makes considerable difference, as young and delicate constitutions have the fundus oculi of a much brighter and lighter hue than is found in older and more robust persons. It is also remarkable that the perfection of vision does not always accord with the apparent condition of the retina, as seen with the ophthalmoscope ; for at times, when it appears somewhat oj)aque and cloudy, the vision is in a perfectly normal state. In such cases, no pathological change is to be inferred; as it evidently depends upon constitutional peculiarity, amounting, it may be, to a physiological phenomenon. On the other hand, we often see a considerable amount of disease occurrinef with tolerable INTERNAL AND EXTERNAL. 115 good vision, or which is often much improved without any- great apparent internal change ; and the inference is, that the disturbance in vision depends upon pathological influ- ences, or results, hidden as yet from knowledge, or only to be discovered by a microscopical minuteness of examination ; to do which properly, we require an ophthalmoscope most carefuUy arranged, and with increased magnifying power. Lastly, I wish to call attention to the fact, that we must not always look for outward signs of change in internal diseases of the eye. In most cases it is well known the external mem- branes are unaccompanied by redness, as in choroiditis, retinitis, and detachment of the retina : indeed, the latter membrane may be the seat of apoplexy, without the exterior of the eye showing in the least any increased vascularity. In keratitis, redness is frequently absent ; hence we may deduce that increased vascularity of the eyeball has no diagnostic value but when taken in conjunction with the physiological signs of the inflammation of each membrane, and is generally in an inverse ratio to the intensity and danger of the disease, with the exception of traumatic lesions and phlegmon. If we glance at internal inflammation of the eye, we find that iritis, in its early stage, is unaccompanied with any very marked redness, and that amblyopia may be unsuspected at a time when vision is already partially destroyed. I 2 IIG CHAPTER V. DISEASES OP THE CORNEA, LENS, VITREOUS BODY, RETINA, CHOROID, AND OPTIC NERVE. Opacities of the Cornea. Nebula, Albugo, Leucoma, and Keratitis ; Conical Cornea, Arcus Senilis. The cornea, as the most exposed portion of the outer tunic of the eye, is subject to numerous contingencies of accident and disease; opacities frequently arise, and these may be either superficial, confined to the conjunctival covering, or may invade its middle or proper structure ; or, lastly, extend to the elastic lamina that forms its internal portion. The opportunity, however, of ready examination which the situa- tion of the cornea affords, and the exactness with which objective symptoms may be examined and estimated, compen- sate somewhat for its unavoidable exposure. The great point, in determining the character of an opacity of the cornea, is to discover its seat ; and this can be done equally well by reflected as by transmitted light ; that is, if the mirror, or ophthalmoscope, be used at all, it must be to throw light obliquely across the eye examined ; for which purpose, it should be held slantingly on one side, whilst the observer in front of the patient examines the case, as under ordinary cir- cumstances. In this manner objects are seen in their real situation as well as colour, and not as dark spots, or rather shadows upon the bright fundus. Sometimes it is necessary to concentrate the light still more, by collecting the rays of a lamp by a condensing lens, whilst a magnifying ocular lens is used in addition, to bring out the details of the opacity with clearness. OPACITIES OF TUE CORNEA. 117 The slightest degree of opacity in any part of the cornea is called a nebula, and, as a class, it includes all spots that have a cloudy or hazy appearance ; and sometimes the whole cornea may be involved in this condition. It sometimes indicates the pressure arising from an undue secretion of the aqueous humour, when its seat will probably be the elastic lamina. Deposit of lymph, however, upon the internal lining membrane of the cornea will produce this appearance. When it is the result of muco-purulent ophthalmia, the conjunctival covering will be chieHy affected ; but lesion of the proper sub- stance of the cornea, occasioned by scrofulous keratitis, produces much more serious forms of nebula. All are readily distinguished from opacities occurring in the vitreous body by the distinctness with which they are observed by oblique illumination ; and being stationary, by their consistent adapta- tion to the movements of the eyeball. Where the exuded lymph in process of disorganization has intensified the degree of opacity, and given to it a kind of pearly lustre, it is usual to call it albugo. This is observed to be more defined or circumscribed in its appearance than nebula in general, and is most frequently seated on the anterior surface of the elastic lamina. It is usual to describe a third kind of opacity as leucoma, and which is simply the opaque cicatrice consequent upon ulceration of the cornea. The history of the case will gene- rally lead to its exact diagnosis, and enable us to distinguish it from albugo, which, in cachectic habits, sometimes assumes appearances as if it depended upon solution of continuity in the cornea, and an actual loss of substance. In all objective investigations of the eye, whenever inflammation of any tissue is present, a particular examina- tion of the vessels around the edge of the cornea cannot be too much insisted upon. Although apparently little to be regarded as likely to be affected by inflammation, experience proves tliat it is in fact extremely liable, and is very apt to become involved when any of the neighbouring parts are so attacked. Dii-ect injury too will frequently bring on kemlUis, 118 DISEASES OF THE CORNEA. and it is one of the evils which sometimes arise, to interfere with the success of an operation for cataract. It is true, that in a healthy system there is little to fear ; but still I could not acquit myseK of proper care to those I am advising, did I not seek to impress the importance of avoiding, when- ever possible, any application of the operating knife to the structure of the cornea. It is this consideration which chiefly recommends to my mind division of the ciliary muscle in aU cases of inter-ocular pressure, an operation first devised by my friend and colleague, Mr. Hancock, for the relief of glaucoma, and to which I shall presently have occasion to refer more in detail. Keratitis is generally first observed about the edge of the cornea, where the vessels derived from the sclerotic coat, and the expansion of the recti muscles, anastomose pretty fi-eely with each other. An enlarging zone of these vessels in a congested state, extending for a line or so into the proper substance of the cornea, reveals the presence of this inflam- mation. Effusion takes place almost immediately ; and in the matter thus thrown out, vessels are seen to spread themselves until the whole of the cornea assumes a pinkish red hue, and its transparency is in a great measure lost. A not unfrequent result is suppuration and ulceration. Keratitis is apt also to arise from the irregular thickening of the substance, and which seems to be connected with a disposition in the inflamed vessels to radiate with cumulative intensity towards the centre. This specific determination is also the cause of a cuticular ulceration, which indicates the commencement of a natural cure, and exhibits in the first place a white spot, surrounded by the dense inflammatory condition known as jpaiimis, from its resemblance to red cloth. Keratitis may always be diagnosed from other vascular ob- scurations of the cornea by the aid of a magnifpng lens, when the apparently diffused ecchymosis resolves itself into a very definite and easily distinguished net-work of minute vessels. I KERATITIS. 119 Keratitis; opacity of cornea; cyclitis ; intense pain and photo- phobia ; operation, followed by almost immediate relief of pain and intolerance of light. — S. W , aged twenty-one, admitted into the Royal Westminster Ophtiialmic Hospital, 15th February, 18G1. She first observed dimness of sight on the preceding Christmas day, whilst suffering from a severe cold and sore throat ; two days after- wards, the right eye became inflamed, the disease subsequently attacking the left eye. She obtained medical advice, and finding no relief at the end of a fortnight, applied at the hospital ; she then complained of intense pain, intolerance of light, and profuse lachrymation of hot, scalding tears. Upon examination, the sclerotic coat of each eye appeared of a pink colour, with a pink zone surrounding the cornea, which were speckled with nebulous spots ; the corneee were un- usually reddened by the large blood-vessels straggling through them. Various remedies were prescribed; but she gradually got worse, until the 1.5th of February, when she could scarcely distinguish light from darkness. Corneas quite opaque and conical, pain and intolerance of light most severe, and lachrymation profuse. Feb. 18. — I divided the ciliary muscle in both eyes. 19. — Passed a good night, quite free from pain. 22. — Much better; still free from pain. When the pads were removed, she said that her sight was decidedly improved ; and complained of the light being too strong. 25. — Still improving; can nowbearthe light well; quite free from pain. She remained in the hospital for another week ; before leaving, she was able to distinguish objects, and read No. 12 type-tests. Keratitis. — J. M , aged nineteen, was attacked, Oct. 1861, with severe inflammation in both eyes, accompanied by great pain, intolerance of light, and increased lachrymation. He became an in-patient at a general hospital for nearly three months, without deriv- ing benefit, and on Jan. 24th, 18G2, was admitted into the Royal Westminster Ophthalmic Hospital. His eyes then presented the usual appearance of long-standing keratitis. He had great pain, intolerance of light, and lachrymation ; his vision was so much impaired that he was obliged to feel his way about. Jan. 27th. — I divided the ciliary muscle in both eyes. Feb. 14th. — Is much improved ; the congestion of the sclerotica and conjunctiva nearly gone. He has had no pain since the operation, and he can now bear the light with comfort. 120 KERATITIS. March 10th. — The cornese are now nearly transparent, and his sight is much improved ; able to read No. 12 type-tests with ease. Double keratitis, with irido-cyditis. — William L , aged 17, admitted Oct. 16th, 1862. Three weeks before, caught a severe cold from an open window; next day found the right eye very painful, which on every subsequent day appeared worse, until he could scarcely distinguish day from night. The left eye was then becoming the subject of a similar attack, and he could only just find his way about when he was brought to the hospital. Both cornese were highly vascular ; photopho- bia and pain intense. Leeches, cupping, and various remedies had been previously tried, without benefit. On the I7th I divided the ciliary muscle in both eyes. Pads were applied as usual, and he was put to bed ; an opiate to be given at bed- time. 18th. — Passed a good night ; refreshed, and nearly free from pain. 19th. — Entirely free from pain ; vascularity cleaving off; with the right eye can distinguish the house-surgeon between his bed and the light of the window. 23rd. — Can count fingers with the left eye ; rapidly improving. 27th. — Corneae sufficiently clear to enable me to make out some slight adhesions in the pupil, ; he was immediately put on a mild mercurial plan of treatment, with tonics. On the 7th February, both corneae quite clear, and able to read No. 8 type-tests ; discharged. I could transcribe frora my note-book twenty similar cases, where medical treatment failed to afford any great amount of relief until division of the cHiary muscle had been resorted to ; after which the patients made rapid recoveries, and, what is worthy of especial notice, without the too frequent sequelcd in such cases of granular lids. In that peculiar form of interstitial keratitis, however, which has been so well described by Mr. Hutchinson, and which is so often seen at all the eye hospitals, there is no occasion to have recourse to any operation. I am perfectly in accord with him, that it is the direct consequence of a syphilitic taint, by descent, as it occurs most frequently in children, one or both of whose parents have suffered from the disease. In these cases, almost invariably, a peculiar charac- CONICAL CORNEA. 121 teristic has l)cen observed ; the upper central incisor teeth being notched and dwarfed in a very singular manner. A mild specific treatment therefore is indicated, and I have found this form of keratitis disappear before a generous diet, the system at the same time being supported by tonics and the use of iodides and cod-liver oil. Sometimes the cautious employment of mercurials is of great service. Conical cornea is due to a bulging of the structure, from a thinning of its several coats, which alter and destroy the natural focus of the eye. The changes in the anatomical elements are chiefly confined to the laminated tissues; and the bulging of the cornea arises not so much from an increase of fluid producing intra-ocular pressure, as from a diminution in the power of resistance in the corneal substances. The indications for the treatment of this disease are, to arrest the softening process, and diminish the internal pressure. Various kinds of treatment have been recom- mended, without more than the very slightest benefit resulting to the patient. Tapping, evacuating the contents of the anterior chamber, I formerly practised under the late Mr. Guthrie's direction, twice weekly for six months or more, without in the least checking the formation of the fluid, or lessening the conical state. More recently, however, myself and my colleagues have seen great success attend upon the division of the ciliary muscle in such cases ; and, as far as we are able to form an opinion, permanent flattening has been the almost uniform result. Before and after the operation, it is our practice to improve the general system by tonics, which is in- deed very commonly indicated by the symptoms present. The ophthalmoscope without the convex lens readily enables us to estimate the degree of conical cornea. The light must be thrown somewhat obliquely, when it will be seen to betray itself prominently by a luminous centre, surrounded by a circle of more or less contrasting shadow. In leucoma, sta- phyloma of the cornea, and sclerotica, division of the ciliary muscle has been attended with marked benefit. 122 LEUCOMA. STAPHYLOMA. Leucoma, produced hy conical cornea, nearly total loss of sight. — W. L. , admitted, April, 1860, with staphyloma of both eyes, and almost total loss of sight, the power of distinguishing light from darkness alone remaining. The cornea of the right eye was so prominent that he could not close his lids ; it was white, opaque, and constricted at its junction with the sclerotica. I divided the ciliary muscle, and he left the hospital in a week, and returned to the country. In the following September, he again presented himself, having derived so much benefit from the operation, that he begged me to operate on the left eye, the cornea of which was more conical than the right had been, causing great pain and inconvenience. The cornea of the right eye operated upon in April was now flattened, and the sight much stronger. I accordingly divided the muscle in the left eye ; and at the end of Nov. he left the hospital, at which time the cornea vfas clearing, and he began to distinguish objects. Staphyloma cornea. — C. F. S , aged nine years, admitted March 3rd, 1861, with complete opacity of the cornea of the right eye, the result of ophthalmia when two years of age. The eyeball was much enlarged and prominent ; nearly the whole cornea was opaque, and very thick and prominent in the centre, but thinner at the margin, where the blue iris was just visible. He had a distinct perception of light. The globe of the eye was unnaturally hard. March 4th. — I divided the ciliary muscle, and a considerable quantity of fluid escaped at the time. loth. — The eyeball is much smaller and softer; the cornea is flatter and clearing at the upper portion, where the iris can be dis- tinctly seen through a space one-eighth of an inch in width, whilst the central dense portion is evidently becoming much thinner towards its periphery. He says sight has improved. Discharged, to attend as an out-patient. Staphyloma sclerotica. — E. B , a female, admitted March 14th, 1862, into the Royal Westm.inster Hospital, under my care, and ope- rated upon the same day. She first observed dimness of sight twelve years ago, and fancied it arose from a very bad confinement. On ad- mission, she could discern the light, and just the shade of her fingers passing. The right eye projected so far that she could not close the eyelids. The pigmental coat of the choroid threatened absorption of the sclerotic, which was bulging considerably behind the comea. The sight of left eye also becoming very dim. I divided the ciliaiy muscle. ARCUS SENILIS. 123 botli on the temporal and nasal side of the right eye, to relieve the great internal pressure as quickly as possible. March 25th, — The bulging of the sclerotic has subsided. She can now close the lids completely, and without difficulty ; has experienced great relief from the operation, and can see her fingers plainly. Dis- charged, and attends as an out-patient. Extirpation or abscission of the eyeball has been commonly practised in such cases ; therefore, if for no other reason, it must be acknowledged that a modified and simple operation, such as I here advocate, is a boon of no ordinary kind to the very poor who are quite unable to purchase artificial eyes ; by this method, also, vision may be sHghtly improved. A very interesting, as it is a most instructive, objective symptom frequently invades the proper substance of the cornea around its sclerotic edge. This is arms senilis. The significance of arcus senilis, or fatty degeneration of the cornea, was fii'st pointed out by my friend Mr. Canton, who has most ably elucidated every point of interest in connection with the subject, in his book lately pubhshed. The arcus shows itself either annularly or crescentically, mostly at the periphery of the cornea as it joins the scle- rotica, of an opalescent or greyish-white coloiu'. Vertical sec- tions of such cornese, when examined by the microscope, are seen to be composed of minute fat corpuscles, and are now considered to be diagnostic of some degeneration of structure going on in other organs of the body, as in the heart, arteries, liver, &c. as well as the muscles of the eyeball, and the ophthalmic artery. Arnold found, in one case, an extensive artheromatos deposit in the ophthalmic artery, and also in the small vessels of the sclerotica. Virchow says that it co-exists with a similar change in the aorta. It has therefore been re- garded, by the last-named author, and by Dr. His, as indicating diminished nutrition, atrophy, or a physiological change produced by age ; whereas, in the middle period of life, it is a sign of more generally diffused morbid processes in other pai'ts of the body. Cheliiis believes it to be the result of diminished. 124 DOUBLE ARCUS vascular activity in the eye, and particularly from diminution of the aqueous humour; and this he thinks explains the occurrence of the arcus most frequently at the upper portion of the cornea, for here is placed the chief vascular supply from the anterior cihary arteries. Arcus is usually developed without any inflammatory condition, although Yirchow re- gards it as very similar to an inflammatory afi'ection of the cornea, " an elementary disturbance which marks those changes which, with a more acute irritation, would take on an inflammatory character." It may, he adds, be regarded as " a clirouic keratitis in which the progressive events have gone on so slowly from diminished nutrition." Dr. Ammon found, in connection with arcus of the cornea, a similar opaque ring round the margin of the lens; and subsequent investigations of Dr. Schon show that arcus affects the posterior capsule as well as the lens, the opacity corres- ponding pretty nearly in form and extent to that of the cornea. Mr. Canton, however, has never met with any change of the kind in his numerous examinations, and is therefore led to regard its occurrence as accidental. As to the extension of fatty degeneration of the cornea, we find the particles mostly of the molecular form, and between its layers ; the anterior and posterior elastic laminae being entirely free : we therefore have a transparent ring between the junction of the cornea with the sclerotica. I have seen patches of fatty molecules imbedded near the margin of the cornea, and without any annulus or arcus pre- senting itself at that or any other portion of the structure ; in other cases, the substance of the sclerotica, for some distance, has participated in the degeneration. If, as I believe, it be a defect of nutrition, it is remarkable that it should occur just at the termination of the capillaries, and be mostly confined to the periphery of the cornea. Double arcus ; rheumatic attach producivg heart disease ; fatty de- generation of retince. — W. P , aged 45, a mechanic, applied for advice- Jan. 3, 18G3. The account he gave was, that vision had been gradually PRODUCED BY HEART DISEASE. 125 failing for some months ; but that he was quite sure his eyes were good before an attack of rheumatic fever which occurred about six or eight years ago, and laid him up for some months. He was then told by the medical man who attended him his heart was diseased. If he gets wet, his old pains in the joints return : heart disease is very readily detected. The arcus is developed in a remarkable manner ; it resembles a double crescent slightly divided midway, between a lower and upper arc. The ophthalmoscope shows considerable deposits in retinae — evidently owing io fatty degeneration. He has been under treatment some three or four weeks, without deriving much benefit. Such cases required long and careful watching, and then only very partial relief or arrest of destruction to sight can be anticipated. Double arcus, with insensibility of retince. — R. W , aged 40, a furniture dealer, applied to me for advice February 9th, 1863, com- plaining of rapidly increased confusion of vision, which he thus describes — " If I try to look at your clock, or a picture, with both eyes, it appears to me that I am looking through a mist or a cloud, and then it altogether suddenly vanishes. I close one eye and look at the clock with the other. I can see the face clearly for a second or two only, when it vanishes. The difficulty is increased if I make an attempt to read or write. I then feel very nervous, and a faintness comes over me, especially after tea and during the evening." The patient, although a thin spare man, has always been equal to his ordinary labour, has lived regularly and soberly, and never had much illness. He is quite sure that he has never suffered from rheu- matism, and no suspicion of heart disease. The pulse rather hard and wiry; the arcus in both eyes is as fully developed as that in the former case. A friend well acquainted with cardiac affections was good enough to examine this patient with me, and we both were decidedly of opinion that the condition of the eyes was due to the presence of valvular disease of the heart. The ophthalmoscope revealed a greyish deposit on the retinse ; this evidently much obscured the small and faintly seen vessels. The vitreous and lens were apparently quite free from deposit. The patient is still under treatment for the general disease in the system, and the last report states with only some slight improvement in the symptoms. 12G LENTICULAR DISEASES. Abnormal Conditions of the Crystalline Lens. Pathology of Cataract. Diabetic Cataract. Injuries to Lens. The slightest abnormal opacity in the lens, its extent, seat, and nature, as well as the size and other relations of the nucleus, admit of exact ai^preciation by the aid of the ophthalmoscope. Wounds, cicatrices of its capsule, small foreign bodies imbedded in its substance, its position m cases of dislocation, can also be accurately discovered : this facility of diagnosis, combined with the more accui'ate knowledge which recent investigations have insured for various forms of lenticular disease, cannot fail to be of great assistance, and enable us to fix with unerring precision the proper method of operation applicable to special cases. Many different forms of cataract are recognized by sur- geons ; and the distinction of true from false — one kind from the other — is a point of no small importance. It is well known that the dimness of sight and opacity in the lens usually begin in a very unmarked manner, and increase slowly for perhaps months or years, until the cataract is ripe — j&t for operation. Opacity occurring in the substance of the lens constitutes true cataract. The affection is met with in all eyes ; but it is most common in old persons. Examined objectively, the opacity generally presents a uniform pearly lustre; but sometimes exhibits a striated appearance, the lines radiating from the circumference to the centre, and in the direction of which it has been known to break up under an operation. There are cases called black cataracts, where the opacity of the lens is of so dark a colour as easily to be overlooked, if not very carefully examined. In these, and in many cases of incipient cataract. Dr. Mackenzie prefers the catoptrical test as a means of detecting their existence. The lighted taper, he observes, " passed in front of the eye, by showing the changed condition of the two deep images, instantly reveals the true state of the lens." CArSULAR CATARACT. 127 Generally, in lenticular catnract, sight is not altogether lost, the patient being ahlo to distinguish degrees of difference in light and shade ; and if the pupil be dilated, a considerable amount of vision may be exerted, where otherwise, in a strong hght, nothing can be seen. Capsular cataract is distinguished as anterior or posterioi-, according to the situation of the oj^acity before or behind the lens. The former is far more frequent than the latter, and is commonly a consequence of inflammation in some neighbour- ing part, and especially in iritis. Threadlike adhesions to the iris seem to take place, on which patches of uveal pigment are often very noticeable, and even remain as a broken ring upon the capsule after dilatation has released the iris. A numerous class of spurious cataracts connected with this condition of the anterior surface of the capsule are enumerated ; all, however, being degrees of aggravation attri- butable to the same cause of neglected or misunderstood local inflammatory action. Posterior opacity of the capsule appears always in radi- ating lines pointing from the centre of the lens, and their indistinct wasting outline enables us to distinguish them from the sharp milky or pearly appearance of anterior capsular opacities. The appearance of posterior capsular cataract is always of serious moment, as indicating the approach of lenticular opacity. Several other specific forms of opacity, connected more or less with the lens, are all described as cataracts, with distin- guishing names. Thus several different forms of an effused opaque fluid thrown out between the capsule and the lens supply four or five varieties of Morganian cataract, the most remarkable objective appearance of which is the difference of colour assumed by the opacity according to the position in which the patient is placed to be examined. In the erect position, the cataract appears of an amber colour, or even a darker brown ; but when examined in a recumbent posture, it presents a challvy white appearance. There is a complication of lenticular opacity with glau- 128 CHOLESTERINE CATARACT. coma which presents a green colour, and is called green cataract ; and in what is termed bursal cataract, a very rare kind, consisting of encysted pus between the lens and the capsule, the colour is orange. But the most singular, as regards appearance, is the sparkling metallic lustre of what is termed cholesterine cataract, from the glancing crystals of that substance moving up and down, so as to have been sup- posed to be small globules of mercury in the aqueous humour. There is a specific affection of the eyes characterised by a green appearance of the pupils, which, when combined with myopia, sometimes leads to serious mistakes in diagnosis. This is now known as glaucoma, and was long supposed, even when plainly distinguished from cataract, to be con- nected with some opacity in the vitreous humour. The oph- thalmoscope, however, has revealed its true character, and enables us at once to determine upon the changes in every case under examination. The peculiar characteristic colour of the pupils in glaucoma is due to a diplochromatic operation which the lens possesses, under some circumstances of altered condition without opacity, such as may be presumed to attend upon an increasing hardness in the centre, and which, reflecting the mean prismatic rays, appears gi-een ; but viewed by transmitted light, has the ordinary amber yellow colour of advancing age. M. Ch. Robin lately pubhshed a very interesting paper on the Anatomy of the Lens, and to which he has appended a Resume of the Pathological Anatomy of Cataracts. First : Lenticular Cataracts. First Species : Soft Cataracts. — Alteration seated in the soft, superficial, cortical layer of the lens. This alteration causes either several whitish or greyish opacities under the form of lines, points, &c. variously arranged, or one uniform opacity. In all these cases the lesion is the same, the difference being only in extent. The alteration of the cortical layer of the lens is due to the facts, that, in consequence of derangements of molecular nutritive process of renewal, and the development of its elements, the latter have undergone morbid modifications of structure, of SOFT CATARACTS. 129' which the following is a description : — These alterations con- sist principally in a tendency to a more granular condition, with a rihbon-Uke flattening of the tubes, which at the same time lose their nuclei. This granular condition manifests itself also, at times, in the serrated fibres. The cells of the lens have disappeared, and are reduced to granules, or rather, from being homogeneous and hyaline, have become granular. At the same time, there are produced, between the flattened tubes, free molecular granules, minute limpid drops, and oil globules. These latter have exuded from the substance of the elementary cells, or perhaps have preceded their disin- tegration. There is, besides, a formation in this superficial layer of solid corpuscles, rounded or of various forms, homogeneous or granular, imbedded or not in a substance of a waxy, homo- geneous consistence. Finally, there is sometimes a deposit of phosphate of lime, mingled with traces of the carbonate of the same base. These various alterations result in a transition in the soft layers of the lens, and sometimes in its hard nucleus from their perfect homogeneousness and transparency, to a heterogeneous condition : to such an extent that the light, instead of passing through these tissues, is reflected by these various particles, and assumes a white or greyish tint, as we see occurring in every granular or heterogeneous substance on which the light falls. Second Species — Liquid Cataract. — This presents a miliy aspect, and there is found contained within the cavity of the capsule, as in a cyst, a whitish liquid, in which floats the hard nucleus of the lens. This liquid is composed of a fluid, holding in suspension fat-globules, corpuscles, and solid granules. It is the change of the normal elements of the superficial layer of the lens to the condition of a liquid, hold- ing in suspension and emulsion the aforesaid corpuscles and globules, which causes its reduction from a state of homoge- neousness and perfect transparency to one in which the light can only traverse it im2)erfectly. It reflects it with a whitish colour, as does every liquid holding in suspension solid cor- K *i30 HARD OATATtACT. piiscles and drops of a liquid heterogeneous as compared with itself. Third Species — Hard Qatarads. — These cataracts preserve to the centre the same anatomical and pathological composition as soft cataracts ; and this is not dependent upon the pre- sence of elements essentially differing from those of the normal lens, if we except the solid corpuscles, whether granular or not, and the fat-globules which have exuded from pre-existing elements in a state of alteration. The lesion consists specifically in an intimate modification of the cellular elements of the lens, causing them to become more solid, each one individually, and more adherent to one another than in their normal state. At the same time, the elements, thus modified, become more granular— rone of the essential causes of the opacity ; the other causes being the production of solid corpuscles and the exudation of fat- globules. Fourth Species — Very Hard Cataract. — This is rare, and is due to an incrustation of the anatomical elements of the soft and hard portions of the lens, which, however, are not destroyed. In this form of cataract the lens is of a greyish or chalky-white colour. It is hard and dense, especially on the surface, and friable, as though granulated ; sometimes throughout its entire thickness, while at others it may present the stony-hard condition only on its surfaces, the nucleus re- maining little altered. The lesion consists essentially in a calcareous deposit, principally composed of phosphate of lime, with only a small proportion of the carbonate of the same base, incrusting, molecule by molecule, the elements of the lens, but not rendering them unrecognizable, if we dis- solve out the salts by means of weak acids. The action of these reagents enables us to recognize here, also, spherical corpuscles, analogous to those of the hard and soft cataracts, which are also incrusted with the calcareous phosphate. Second Class — Capsidar Cataract. First Species — Pseudo -membranous Capsidar Cataract. — This, as its name indicates, is characterized, anatomically, by CAPSULAR CATARACT. 131 the production of filaments, or of a fine pseudo-membranous layer, which probably originates from the iris, having been in communication with it, and ceases to adhere to it while it remains fixed to the iridial face of the anterior crystalloid, to its centre especially, which is its most prominent part. The morbid production consists of a non-vascular tissue, firm, somewhat difficult to tear, of a striated aspect; the striae being sometimes undulatory, and presenting, on laceration, a lamellar rather than a fibrous structure. This tissue is usually incrusted, but only at a definite period after its appearance, by a quantity of microscopic granules, generally of a rounded form, composed principally of phosphate of lime, with a little of the carbonate of that base. Second Species — Pliosphatic Capsular Cataract. — This is characterized by the production of granules similar to those in the preceding class, and of the same nature, which are im- bedded in the substance of the anterior crystalloid, but on its iridial aspect only. The opacity manifests itself when these granules are sufficiently large and closely approximated to interfere with the transmission of light, and form masses of sufficient size to be perceived by the surgeon, under the form of spots, lines, or of whitish points. It is more rare than the preceding form. For some years past the attention of the profession has been directed to the frequent association of cataract with several forms of general disease existing in the system ; and this has given rise to investigations which fortunately have been attended with results of a very satisfactory character. ■ In previous editions, I have mentioned that Mr. Jordan had satisfactorily shovsii that cataract is intimately connected with heart disease ; and every one must admit the soundness of his general view : " That there should be an intimate con- nection between cardiac and ophthalmic disease cannot, a priori, be deemed improbable to any one prepared to admit the connection between diseases of the heart and diseases of the brain. Shall the central artery of the retina maintain its integi'ity amid the ravages of a disease which does not K 2 132 DIABETIC CATARACT leave the divisions of the internal carotid itself competent to the performances of theii- duty ? The purely mechanical protrusion of the eye attending a hypertrophic heart is a condition now commonly appreciated. But there are other and more delicate conditions of the visual organ, telling of cardiac states so palpably that they shall challenge the credence of the accomplished physician and surgeon/' My own observations had previously assured me that cataract is very often associated with ill-feeding, or an im- poverished state of the blood. An anaemic condition of the retinal vessels is almost always present in the early stage of the disease; the fact induced me to push blood tonics, believing that, by improving the blood, and by attending to the general health, I might perhaps arrest the formation of cataract. The treatment I consider to have been very suc- cessful, as in many cases I have noticed opacities remaining stationary for four years and upwards ; during the greater portion of which time the patients were under my own observation. Another serious and not uncommon complication of cataract is associated with diabetes meUitus. A French oculist, indeed, goes so far as to declare that he has on more than one occasion diagnosed the existence of glycosuria from the peculiar anatomical character of the cataract. It is generally of the soft variety, large and full, frequently pressing forward the iris against the cornea, so as to fill the whole of the anterior chamber. The development of this kind of cataract is likewise very rapid. The practical importance of detecting this complication, when present, as stated by M. Folliu (of the Necker Hospital), depends upon the difficulty of pro- curing adhesion of the corneal flap in extraction, and in the danger of inflammation and irido-choroiditis if depression is the course adopted. It is therefore highly necessary, before proceeding to an operation, to learn the state of the urine, as the total want of reparative power which chai'acterises glycosuria affords very little prospect of success if its presence be detected. Where circumstances, however, do authorise ARTIFICIALLY PRODUCED. 133 an operation, as extreme desire on the part of the patient, as M. Follin has properly pointed out, the after treatment must be very different from that in ordinary cases, and consist of the most nutritious food and the generous use of wines. In a paper, published in the American Journal of Science for January, 1860, Dr. Mitchell asserts that "Cataract maybe produced artificially by overcharging the blood of an animal with sugar." The fact has been established by other experimenters ; and it is considered to be purely osmotic : that is to say, due to an excessive transudation of water from the lens to the surrounding fluids, upon which the component parts of the lens are disarranged, and opacity is the result. This form of cataract connects itself intimately Avith what has been made out in the etiology of the disease, as to the co-existence of diabetes and cataract. ■ Dr. Richardson has more recently confirmed the experi- ments made by Dr. Mitchell, and arrives at the following conclusions : — 1. " In addition to the sugar- cataract, there is producible what may be called a saline cataract. 2. The appearances of the cataracts, as produced by different solu- tions, vary ; thus the cataract, artificially produced by chloride of sodium, differs from that produced by grape- sugar. 3. The cataractous appearance is modified by the density of the producing body, and is removeable by reversing the conditions which have led to it ; and as it is producible in a clear lens removed from a body, it is a demonstration that the cataract induced in different animals is a purely physical, osmotic change." There can exist no doubt as to the frequent dependence of a cataractous condition upon the diabetic malady ; and, in fact, the connection between the two diseases has been noticed by many trustworthy observers. Mr. France published several cases, and says : " The characters which the cases in question displayed have been sufficiently uniform to enable me to recognize them, before any complaint of urinary disorder was preferred by the patients. The cataracts have in every example been symmetrically developed on both 134 DIABETIC CATARACT. sides ; the lenses have increased remarkably in their anterio- posterior diameter, so as to encroach upon the depth of the anterior chamber, and even to interfere mechanically with the free play of the iris. The opacity has attacked portions of several strata of the crystalline at once, leaving inter- mediate spaces for a while transparent. The colour and bulk of the cataracts have invariably indicated their soft consistence, which was proved by operation in two persons, though respectively of ' middle ' and of forty-eight years of age. Lastly, the ocular affection has only arisen after a considerable duration of the renal malady; and there has, in no case, been reason to suspect further disease of the eyeball. " My experience would lead me strenuously to deprecate any operative interference with them, so long as a useful degree of vision is preserved ; and to adhere to palliative treatment by mydriatics for a longer time than in ordinary cases of cataract would be expedient or right. This recom- mendation is chiefly founded on the indisposition of the cornea to heal even the minute wound inflicted by a needle, as illustrated by the first of my cases. A period, how- ever, arrives, when all useful vision is extinguished; and then, unless the general powers are rapidly failing, there can be no doubt of the duty of attempting to afford rehef. Depression (if not on other grounds to be discountenanced) would be clearly inapphcable here, as indicated by the uniform signs of softness. "There remain, therefore, only the varieties of the opera- tion for solution available, and keratonyxis should be selected in preference to any other mode. In performing it, the surgeon should be more than usually scrupulous, to employ a needle of the greatest dehcacy; to make sui'e that the shaft will completely fill the aperture made by the point ; to confine his fii'st manipulations to a narrow area in the centre of the capsule ; to effect his purpose at that spot steadily, in as brief a time as may be ; and carefully to withdraw the needle, Avith the flat surfaces of its point as they were introduced, J PHOSPHENIC RETINOSCOPY. 135 parallel with the plane of the iiis, and thus to avoid the minute crucial wound otherwise necessarily inflicted. The neglect of these precautions, by permitting escape of the aqueous humour, would probably render the whole process abortive." There has recently been introduced from Paris a process for ascertaining the condition of the retina, where, from opacity of the lens, the ophthalmoscope cannot be used, which its proposer, M. Serres d'Uzes, caUs "•phosphenic retinoscopy." It promises to be extremely useful, as it enables the surgeon fairly to anticipate the probable restoration of vision as the result of an operation, or, on the contrary, be sufficiently conclusive to interfere and prevent a patient being exposed to useless i)ain without the chance of any amendment in vision. The mode of mvestigation is somewhat similar to that which is adopted in examining the eyes by tactile pres- sure. The patient, with his back to the hght, closes his eyes gently as in sleep. Slight pressure is then made in different regions of the eye with the extremity of the fore- finger, or any blunt rounded instrument that may be found convenient. The pressui-e should be made as deeply towards the back of the orbit as can be done without inconvenience, the eye at the same time being directed in the contrary direction. A luminous circle, or arcs of a circle, if the retina be healthy, will be simultaneously seen by the patient, on the side opposite to the poiat of pressure ; and if the phosphene appears in succession all around the eye, according to pres- sure made, the inference is that the whole retinal expansion is functionally sound, and the prognosis of an operation accordingly would be favourable. If, on the other hand, the pressure produces only blank impression, it may be presumed that the retma is so far implicated in the disease that an operation would be useless, or its success very problematical. M. Serres describes four phosphene regions where pressure maybe made >vith the best effect. These are iliQ frontal, the pressure being made from above ; temporal, where it is made at the outer angle of the orbit ; jn(jal, from below ; and the nasal, from the inner angle. He has also determined the 13G listing's test. order in which these 2)^iosphenes disappear, in cases of pro- gressive disease of the retina, and states it to be : first, the jugal, then the temporal, then the frontal ; that observed at the nasal region continuing to be seen after all the others are lost. These phenomena have also been made a measure of the progress of cure; and, it seems, the restoration of nervous power, as indicated by the reappearance of the phosphene, is in the reverse order to that above given. It is advisable, in all cases of cataract, before proceeding to use either the ophthalmoscope or convex lens, to dilate the pupil with atropine, by which means we obtain a view of com- mencing striated opacities at the very edge of the lens. Listing extols the entoptic test for discovering lenticular opacity in the incipient stage. The patient is desired to look at the clear sky through a small hole in a card made with the finest sewing needle ; in this way the abnormal opacities are readily brought into subjective contemplation as various dark spots and streaks "in the field of dissipation of the nearly parallel homo- centrical light, and in general can be perceived earlier than it is possible to discover them as objects from without ; and it is hereby demonstrable that these dark spots, which prevent the course of the rays of light through the dioptric media, are situated at a small distance from the pupil, in the lens or near its capsular covering," It is quite unnecessary for me to dweU upon the import- ance of being able to diagnose with absolute certainty the cataractous form of disease. The question of cataract, or other change in the dioptric media, we are expected to decide without hesitation ; and the opinion given will implicate the character of the medical man in the issue of the case. In former times, it was very difficult to determine, not only the existence, but the seat of the cataract, and to say whether an opacity was one affecting the crystalline capsule, the lens, the vitreous humour, or depended upon a change of the retina, or of the choroid coat.* * Dr. Mackenzie very properly dwells upon the importance of being able to distlnguisli the early stages of cataract from amaurosis. He observes: AMAUROSIS AND CATARACT. 137 A short time since, a meclianic presented himself to me at the hospital, who had been pronounced amaurotic. No visible change could be detected in the dioptric media by- daylight. I examined the eye with the ophthalmoscope, and perceived a grey-coloui'ed central opacity on the posterior capsule of the lens. The vessels of the retina and optic nerve, at first seen with difficulty, were, after a little search- ing, found in a nearly normal condition. It is not improbable that the opacity commenced after this patient was pro- nounced amaurotic ; nevertheless, the fact is worth recording, and shows the value of the ophthalmoscope in all cases of doubt. In another case which fell under my observation, the patient was about to undergo a needless operation for the restoration of her sight. Mary F came to London for the purpose of submitting to the operation for supposed cataracts. Upon examining the eyes with the ophthalmo- scope, the lenses were found perfectly free from disease. In the left eye a crescent of pigment surrounded the periphery of the optic nerve, and a small apoplectic clot covered the centre. In the right eye, a black spot covered the fora- men centrale, and dark grey bodies floated in the vitreous. The vessels and optic nerve were much obscured by the large amount of blood in the eye, and by reflection it imparted an apparent opacity to the lenses; this had evidently misled when the ordinary mode of examination alone was thought sufficient to decide the state of the case. The joatient, a " If a patient with incipient amaurosis presents himself to a practitioner who mistakes the case and supposes it to be one of incipient cataract, the advice which he will give will be to wait with patience till the disease be fully de- veloped, then to submit to an operation. Should the patient return after some months with a fully developed amaurosis, instead of a cataract, the practitioner would necessarily feci that he had lost the only season for treat- ing an amaurotic affection with success. The opposite mistake would proba- bly lead him to the employment of depletion, mercury, and counter-irritation, by which his patient's health might be seriously injured, but which could have no effect in removing an incipicnf opacity of the lens."— Mackenzie's ' Diseases of the Eye,' 4th Edition. 138 OPACITIES IN THE delicate woman, was suckling; and to this in part may be attributed the deterioration of sight. A blacksmith, whose imperfection of vision in the right eye had been said to proceed from incipient cataract ; the oph- thalmoscope showed the opacity to be one of reflection, from internal congestion, and the patient was cured by local abstraction of blood, perfect rest, and brisk purgation, fol- lowed by tonics. Diseases of the Vitreous Body. Cysticercus. The vitreous humour is frequently the seat of opacities ; but some caution is necessary in determining the character of such defects, as they are nearly always associated with either choroidal or retinal disorganization — sometimes thread-like traces of the nourishing vessels becoming more prominent than in the normal state; presenting an appearance not inaptly described as funnel-shaped striated nebulosities. lu the healthy eye, this filamentous structure is with difficulty to be discerned, as the delicate fibres are transparent, and pos- sess a refractive power nearly the same as the general mass of the vitreous in which they repose. They may be best observed in the foetal state, as they consist of the branches of the hyaloid artery, which disappears as its function of deve- loping the vitreous body is accompKshed. Their remains, however, may be plainly discerned in certain pathological conditions in the adult. An interesting case, recorded by Coccius, well illustrates the real nature of this filamentous structure ; and also the changes in the appearance of the vitreous produced by disease. "A woman, 36 years of age, had suddenly remarked, four weeks previously, a cloudiness of" the visual field ; this in a few hours had so much increased that she lost all power of recognition, and was obliged to be led by another person. Externally, the eyes seemed normal, the iris of a bright green, and somewhat inactive. The vitreous body was fluid, VITREOUS BODY. 139 and contained small point-like opacities ; some of the particles behind the lens moved over the whole length of the vertical and transverse diame- ters. Towards the fundus, a number of vessels, which slowly changed their position as the eye was rotated in various directions, in the right more than in the left eye ; the longest of them projected as far as the middle of the vitreous body, where it ended in a long white row to a point, and was lost in the upper part of the globe. Many such threads were seen connected with short vessels, which appeared to be terminal capillary loops. The retina was extremely vascular ; vessels which ap- peared to be on the surface of the retina when the eye was at rest were seen to move in small curves by means of violent motions of the eye. The retinal veins were extremely tortuous, and in many parts com- pletely covered by opaque retina." After watching this case for many weeks, Coccius became convinced that these vessels in the vitreous body were really extensions of those of the retina ; they were connected both with the venous and arterial branches of the retina. Their size was about that of the average arterial vessels in the equatorial region of the eye, and they all sprang from near the entrance of the optic nerve. No boundary between the papilla optici and the rest of the fundus could be perceived. In the right eye there occurred, at a subsequent period, a considerable extravasation of blood, which yielded to antiphlogistic treatment, and the vitreous became somewhat clearer. Effusion of blood into the vitreous is a cause of opacity, a cloudiness extending some distance around the clot. This affection is apt to occur suddenly after violent exertion, and is sometimes called apoplexy of the eye. It may also arise spontaneously from constitutional weakness of the vessels. Grafe describes cases in which he has recognised this condition, and also intra-ocular boemorrhages, occurring periodically dui'ing intervals extending over several months. Opacities due to these causes are best observed by light thro-svn obliquely into the eye, after the pupil has been properly dilated by atropine ; the clot being then examined by a double convex lens. An instructive case, where a remarkable ossific deposit had obliterated the vitreous body, is described by Spree, an eminent Belgium oculist, and quoted by Mackenzie in his Treatise of Diseases of the Eye. An operation for cataract 140 FLUIDITY OF THE \T:TRE0US. had failed in restoring sight, and the patient continued to suffer pain in the eye till the time of his death. On dissec- tion, morhid adhesions were found between the choroid and the neighbouring parts ; there was no trace of the retina, and in place of the"\dtreous body there was a long substance, con- Yex posteriorly and concave anteriorly, and half an inch in thickness. It is not improbable that the imperfect means of diagnosing affections of the eye, available at the date of this extraordinary case, led to a false conclusion, and that a useless operation for cataract was the result. It is weU always to bear in mind that many cases of opacity due to ossific deposits within the vitreous body are on record ; and it frequently happens that a lens depressed into the vitreous becomes ossified, or very hard, instead of being absorbed, and thus interferes with the success of the operation. It may also fall forward through the pupil when the patient happens to stoop, and then it becomes a source of great irritation and local inflammation. Fluidity of the vitreous body, without myodesopia (float- ing substances in it), I do not remember to have seen; and the large quantity of muscse which I have observed floating about in some eyes, induces me to believe that a great portion of the pigmentum nigrum must have become detached, escaping into the vitreous. In a case lately examined, the patient being fifty years of age, his eyes, upon casual inspec- tion appearing free from disease, the immense quantity of floating bodies siu-prised me ; nevertheless the man had been jDronounced an impostor. Irrespective of those numerous false subjective symptoms of fancied obscurity so frequently complained of by glaucoma- tous patients, and which might be suspected, as occasioned by the presence of floating bodies in the vitreous, it is now known that microscopic corpuscles may exist ; and when once a person detects them, such frequent notice is taken of them that they become exceedingly troublesome. Eyes so affected present little or no change whereby the existence of the cor- puscles can be detected; but all doubts as to the natui-e MUSCiE VOLIT ANTES. 141 of such cases are now readily cleared up by the use of the ophthalmoscope, which has also led to many important modi- fications in the diagnosis, and consequently the treatment of many diseases of the eye. An oblique Hght from the plane mirror shows these changes, as I have remarked before, in the vitreous better than a convex mirror, and there is no difficulty in determining the position of exudations, or of corpuscles between the cornea and focal centre of the eye, or between the focal centre and the sensitive layer. In such changes, we no longer depend on philosophical reasoning for an expla- nation of the cause, in most cases, of this heretofore obscure disorganization ; the ophthalmoscope now clears up the diffi- culty, and gives a better explanation than philosophers were wont to give, and whose experiments, in some instances, it appears to me, must have originated bodies having no real existence in some eyes when experimented on. I might instance the experiment of causing a person to search for muscae " through a pin-hole made in a card, or the eye-glass of a compound microscope " — a fallacious mode of procedure, since we find, by placing a card with a pin-hole in it before the eye, external objects, as particles of very fine dust, constantly floating about, or the eyelashes are, in this way, much magnified, and at the same time so ill-defined as to puzzle most patients; and whether the objects seen, are floating outside or inside the eye, they cannot positively say. *' Nothing serves so much to increase the perception of muscse volitantes as often searching for them through pin-holes, lenses, &c. Such experiments seem to rouse them into existence ; and he who has thus brought himself to discover them, continues to see them, and cannot get quit of them."* Although diseases of the vitreous humour are not at all un- frequent, patients often complain of spots, flakes, or shreds, ap- parently before the eye, where I have been unable to detect the presence of any exudations in the vitreous, but have found a congested state of the retinal vessels sufficiently great to * Dr. Mackenzie. Op. cit, 142 SPECTRAL MUSC-S!. account for these supposed shreds or spots. In such cases, the removal or abatement of the probable excitmg cause is the first thing to be attended to. Rest to the eyes, if they have been overstrained, relaxation from business, quiet to the mind, a well-regulated diet, exercise, and change of air, afford a wide margin of opportunity for improvement. In the fol- lowing case, I observed a curious condition in the vitreous body, which was the cause of the muscee complained of. S. M , aged 25, complained that for four years her left eye had been affected with a constant appearance of dark spots obscuring vision, and had never been so strong as the right. On the least exposure to cold, she suffers from ophthalmia, and frequently feels severe pain in the head, with dimness of sight. Can see objects distinctly at a distance ; but when looking at near ones, they appear misty and as if covered with black spots, or a veil were interposed. There is very slight diffused opacity of the cornea. Examined with the ophthalmoscope, a floating greyish mass in the vitreous humour could be seen, which at times floated up and obscured the optic nerve ; the vessels of the retina could then only be made out with difficulty. Alteratives and a mixture of soda and decot. cinchon, were prescribed, with change of air ; and in a month the patient was considerably improved. Floating bodies, muscge, are not unfrequently the cause of very troublesome spectral illusions. A young lady suffering from muscse often imagines she sees persons or animals moving about her room, which is particularly troublesome towards evening, or in a dull Hght, as then the pupils become dilated. This condition will explain many curious illusions of which we hear, and find associated with particular tempera- ments, and in hysteria, hypochondriasis, febrile and other affections ; mostly ciu-able by judicious medical treatment. "An optical spectrum is seen when the eye has been strained by looking on any particular object or colour. The ray of white light consists of the three prismatic or primitive colours. Now, if the eye is fatigued by one of these coloui's, or it be lost, mechanically or physiologically, the impression of two only will remain, and this accidental or complementary CYSTICERCUS. 143 colour is composed of tlic two remaining constituents of the white ray. Thus, if the eye has been strained on a red colour, it is insensible to this, but perceives the hlue and the yellow, the combination of which is green. So, if we look long on a green spot, and then fix the eye on ivliiie paper, the spectrum will be of a light red. A violet spot will become yelloio ; a hlue sj)ot orange-red ; a hlach spot will entirely disappear on a white ground, for it has no complementary colour; but it appears ivhite on a darh ground, as a white spot will change to black. The colours of objects are also changed in some cases in ophthalmia ; the eye, from certain diseases of the nerve, may only see half its object; the same things may appear and disappear alternately ; objects at rest may appear in motion, and the spectral images of persons and things formerly seen may be exactly reproduced. Even more than this may occur physically, for material objects may seem what they are not, and especially under certain predis- posing causes of a mental nature. " Optical illusions at times present themselves in very curious and mystic aspects, which is, doubtless, owing as much to some temporary derangement of the organ of vision, or to that of bodily ill health, as to external refraction.'^* Ctjsticercus. — The presence of entozoa in the deeper parts of the human eye has only been demonstrated since the intro- duction of the ophthalmoscope into medical practice. Nu- merous cases, however, are now on record, especially in the annals of German ophthalmology. In England they appear to be of much rarer occurrence ; and considerable care is required, in the examination of such cases, not to be led into error, as common encysted tumours sometimes bear a very remarkable resemblance. They have long been known to invade the areolar tissue of the orbit and the anterior cham- ber, where, of course, they admit of a much easier recognition than when they are believed to exist in the vitreous humour ; or, as Von Grafe alleges, who was the first to describe them * Demly's 'Philosopby of Mystery." 144 CYSTICERCUS in these situations, between the hyaloid membrane and the retina. In the most favoui*able cases for diagnosis, the head and body of the cysticercus may be seen through its delicate enveloping membrane ; and when this has not been possible by the increased turbidity of the vitreous humour, by fixing the axis of vision, the walls of the vesicle will sometimes ex- hibit flattenings, or cup-Hke depressions, alternately produced, and simultaneously in several places, together with the movements which diffused themselves in an undulatory manner. Changes also take place in the choroid, which assumes a pale yellow colour in the vicinity of the entozoon, and an effusion of serum may take place beneath the retina. The transparency of the vitreous becomes affected, and a film- like opacity may be observed. Vision is very considerably diminished ; and as it is not unusual in such cases to find the system generally predisposed for the appearance of entozoa, in some form or other, inquiiies into the history of the case will materially assist our diagnosis. Grafe gives the particulars of many interesting cases of cysticerci occurring in the vitreous humour, in patients whose ages varied from 10 to 53 years. Two cases occurred in males, suffering at the same time from taenia ; four cases occurred in females, one of whom only was affected with tsenia, and had cerebral symptoms, with paralysis of one arm, co-existing ; supposed to have been produced by cysticerci in the substance of the braiu. The parasites residing in the vitreous humour were enclosed in a membranous sac ; and it seems that they were supported for a long period with com- parative immunity of the other structui-es of the eye ; whereas, if developed on or under the retina, they generally excite inflammatory action, producing detachment of the retina by choroidal exudation, development of opacities in the vitreous humour, &c. with consecutive atrophy of the eyeball. The following case by Grafe illustrates the appearances presented by cysticercus in the vitreous humour : — IN THE VITREOUS BODY. 145 H. M , from Posen, a boy, ten years old, complaining of am- blyopia of the right eye. Slight green discoloration of the iris, but no parenchymatous eftusion. Pupil slightly dilated and sluggish. On ophthalmoscopic investigation, a cysticercus is discovered in the vitreous humour, enclosed in a membranous sac, which extends from a point just behind the posterior pole of the lens, and diverges, fan -like, in a system of radiated offsets, towards its posterior surface. Thence the sac extends nearly directly backwards, and is attached to the papilla of the optic nerve, which, with the exception of two narrow segments, is hidden from view. The fundus of the cysticercus itself seems to be situated in the middle of the vitreous humour, where it is distinguished by a sharp contour from the continuation of the sac. Just above the insertion of the sac, on the papilla of the optic nerve, some spots of yel- low retinoid and sub-retinoid exudation were visible ; the retina and choroid otherwise normal. The undulatory motions of the parasite were distinctly visible. After two months, no change had occurred. In a similar case, described by Liebreich, no change was visible after nine months. In No. 4.5 of the ' Deutsche Klinik' for 1856, Grafe describes a moveable Cysticercus cellulosm in the vitreous humour of a patient, which exhibited turbidity, in consequence of the irritation to which the foreign body gave rise. Grafe made an opening through the sclerotic coat, and extracted the Cysticercus, with great difficulty. In this operation, the caudal part of the vessel was torn off, and the head and neck only, which were seized by a pair of forceps, could be got out. Under the microscope, the suckers of the Cysticercus were seen to move for twenty minutes. The vision of the patient improved ; he could read large print, count fingers, go out, &c. Cysticercus in the retina. — In this case, the patient observed, three weeks before his visiting Grafe's hospital, a cloud in front of the left eye, in the middle of the field of vision, diffusing itself thence towards the sides, so that he had perfect sight from the sides only, whilst in the axis of vision large and strongly-illuminated objects were seen as if through a thick cloud. In course of time, however, sensibility to light was en- tirely extinguished. The lens and vitreous humour were clear ; but in the retina, a shining greenish body was seen, which was bordered by convex circular margins, and lay a little outwards from the centre of the retina, on the outside of the optic nerve. Examined in the indirect L 14G INJURIES TO THE CORNEA. manner, the body appeared as a perfect, roundish, greenish vesicle, four times larger in diameter than the entrance of the optic nerve. It was decidedly attached to the retina, and projected into the vitreous body, in which was perceived a white, button-like, projecting appendage, dis- tinctly marked by its greater opacity and its colour, which shifted its place, and over which vessels ran forwards. In three weeks the vesicle had increased about one- third in diame- ter, and reached to the optic nerve. The head had passed from the centre to beneath the upper margin, and appeared to have grown like a small vesicle out of the previous one ; that is to say, the enveloping cyst had probably burst, and a small vesicle protruded which reached to the former. The retina had lost its normal colour, and was covered with irregular, blended, pale spots, of which Griife did not know whether they lay in or behind the retina. In five months, the first vessel was completely collapsed; and, instead of it, a folded trans- parent membrane, without determinate outlines, was to be seen moving up and down, and the second vesicle also was less distinctly detected with indeterminate outlines. The animal, however, was still alive, and its head lay towards the nasal side. Cystic worms appeared in no other part of the body, nor did the patient suffer from tape-worm. Wounds and Injuries to the Eye. Injuries to the cornea from blows, or by detached pieces of foreign bodies striking it forcibly, are so evident on examination as to require little comment here. The most serious consequence of such injuries is where the rupture of the cornea ensues and the eye collapses, from the escape of the humours. In some cases, however, the laxity of the con- junctiva admits of its yielding without being torn, the tense sclerotica at the same time giving way under the violence inflicted. The lens has, under these circumstances, been ob- served protruding as a small tumour beneath the conjunctiva. An ordinary consequence of accidental division of the cornea is a prolapse of the iris appearing ; this membrane is seen protruding through the opening. The choroid is also INTRA-OCULAR EFFUSION. 147 frequently implicated, yet with good management vision will not be wholly lost, as in tlie following case : — Henry D , aged eighteen, admitted November 7th, 18G0, under my care. Whilst employed the evening before, a sharp piece of steel, upon which he was at work, flew up and struck his right eye with con- siderable force. This cut through the nasal side of the sclerotica and cornea to the extent of a quarter of an inch. The iris and pigmental coat of the choroid protruded through the wound. He could not see daylight, and the eye gave him great pain. The anterior chamber and internal eye were filled with blood ; no lens could be seen. He was put to bed, and a soft pad applied. To take a quarter of a grain of opium every four hours. Nov. 8th. — Has passed a comfortable night. 11th.' — A small quantity of vitreous humour escaped on removal of the pad. A piece of iris protruded ; this was removed, and a drop of solution of nitrate of silver applied. 13th. — Ordered quinine with iron mixture. 15th. — Wound united, and on the 17th he was discharged; to attend as an out-patient, 23 rd. — Wound quite healed ; has recovered some amount of vision. There are no cases in which the advantage of the ophthal- moscope is more marked than those where the sight has been injured by traumatic intra-ocular effusions, as the following well illustrates : — " A young gentleman had been educated for the army, and in due course presented himself for examination before the military surgeons. When the sight was to be tested, the surgeon placed his hand before the youth's left eye, when lo ! he could discern nothing with his right. He was a remarkably fine young man, and there was nothing to be seen under ordinary examination which explained his absence of sight. The only circumstance bearing on it which he could remember, was a severe blow on the eye from a cricket-ball some months previousl3\ The ophthalmoscope at once revealed the nature of the injury. There was no retinal reflection whatever ; a clot of greenish hue, doubtless blood poured out at the time of the blow, occupied the posterior portion L 2 148 PENETUATING -VVOlilSrDS. of the vitreous chamber, and completely prevented all vision. I was obliged to express an unfavourable opinion as to the probable restoration of sight. When a clot has remained so long, with Uttle change beyond the loss of the red particles, there is small hope of its removal. The difference between the activity of absorption of blood from the aqueous chamber and the vitreous chamber is very great : I have seen the aqueous chamber cleared in twenty-four hours. Slow, on the other hand, is the disappearance of even a small effusion, when poured into the vitreous chamber."* Detachment of retina, imth coloboma of the iris, the result of injury inflicted by the firing of blank cartridge. — William D , aged 19, applied to the hospital Sept. 22nd, 18C2. — The accident was occasioned in the following manner: — On Easter Monday, being out with his corps, the Wilton Rifles, and some distance in advance of a firing party, he received a violent blow to the nasal side of the right eye from a blank cartridge, which entirely deprived him of sight. He was at once taken to the infirmary, and carefully attended to. At the end of five or six weeks he could distinguish daylight ; he now sees the outline of large objects. The pupil is drawn downwards and inwards, and to the nasal side. The iris is of a duller colour than that of the left eye, and bears evidence of an old iritis ; there is also an extensive colo- boma. The ophthalmoscope renders visible a square-shaped detached portion of retina extending from the iris to the optic nerve, which waves about when the eye-ball is put in motion. No vessels can be seen on the same side. A good deal of chorio-capillary congestion is still visible.f In penetrating wounds of the eye, the ophthalmoscope is of the greatest use, as the situation of any foreign body that may have entered and been left behind is readily discovered, after the absorption of the effused blood, which in the first instance often fills the aqueous chamber. Dr. Jager records an instructive case : — "A workman, engraving steel, was struck by a chip, which, passing through the cornea and iris, lodged in the vitreous humour. Without suspecting the danger of his wound, he consulted Dr. Jager ten days * Mr. White Cooper, Lancet, 1862. f See plate 1, figure 4. RUPTURE OF THE GLOFjE. 149 after, for a slight affection of the sight. There was only a very small trace of a wound in the cornea and iris. On examining the transparent media, a foreign body was seen enveloped in plastic exudation as a con- sequence of inflammatory action, the fragment of steel became encysted at the end of another week ; the vitreous humour recovered transparency, but the sight gradually declined. Five weeks after the accident, sepa- ration of the retina was discerned in the neighbourhood of the cyst. The separation soon extended over a third of the inferior and anterior portion of the retina, whilst a portion of the encysted fragment had moved from its first position, and was gravitating towards the middle of the eye. This displacement was attended with a slight pricking in the external parts of the eye. A plastic deposit then formed, raising the retina and hyaloid in the form of a cone, at the summit of which was the encysted body- In three months the fragment had reached the centre of the globe. At first horizontal, it had now become vertical. The eye retained its form, the lens its transparency, and there was some amount of side vision." With regard to cases of this sort, more than ordinary- care is required in their investigation, to prevent any mistake as to the true situation of the foreign body ; for in the illu- minated field of the ophthalmoscope it may appear as if in front of the lens when it is actually behind it. Rapture of the globe, with dislocation of the lens. — William F , aged 48, admitted Oct. 5th, 1860. The patient, a baker by trade, stated that, five weeks before, he was struck on the left eye by a drunken companion, causing an extensive rupture of the globe towards the nasal side, separation of five-sixths of the ciliary processes, and dislocation of the lens into the anterior chamber. A quantity of coagulated blood filled up the space behind the lens. Ptosis and internal strabismus immediately followed the receipt of the injury. He was attended by his usual medical man, who ultimately sent him to the hospital. When admitted, vision was wholly lost, and the pain more severe than for some days before. To relieve this pain and re- store the part to a more natural condition, I extracted the lens, and with it the coagulated blood. This was done by a small upper section, and with considerable relief to the patient. A soft pad being afterwards applied, he was put to bed, and slept better than he had since the accident. 150 DISLOCATION OF LENS. Oct. 7th. — A little puffy swelling about the lid. Having been ac- custonfied to the use of stinaulants, he was ordered full diet, with six ounces of gin daily. On the 12th, the eye was opened; the patient could see light with it, but the flap had not firmly united. 24th. — Going on well ; can see more light ; no strabismus, but still unable to raise the lid. To take small doses of grey powder with quinine. Nov. 6th. — Although gradually improving, the ptosis is still per- sistent. To change his medicine for strychnine, one-sixteenth of a grain thrice a day. 16th. — Discharged, much improved; vision considerable; has power over the movements of the eyeball, and some over the lid, being able to raise the latter sufficiently to see objects on the floor. Dislocation of the lens is a veiy common consequence of injuries to the eye from severe blows, and cases are recorded where, in debilitated or naturally weak constitutions this occurs, from over exertion, and during severe fits of coughing, or even sneezing. The best way of deter- mining whether the crystalline is in its natural situation or not, is by the catoptrical test ; for if not in its place behind the iris, neither the inverted nor the more deeply erect image of a lighted taper passed in front of the eye will be visible ; only the image formed upon the cornea. An interesting case of dislocation of the lens into the anterior chamber of the eye during a fit of violent sneezing occurred in my own practice. Dislocation of the crystalline lens into the anterior chamber of the left eye during a fit of sneezing ; displacement of lens in right. — A. B . aged 36, a German, had always been myopic. Two months ago, the sight of the left eye became unusually acute, so much so that objects appeared as though seen through a magnifying glass, the nose seeming to him ver}'- prominent, and thereby causing much discomfort. On the 18th of April he was taking a walk, the sun shining strongly on his face, when suddenly he felt as though blinded in the lefl eye ; he immediately put up his hand and rubbed it. It should be stated that DISLOCATION OF LENS. 151 just previous to this he had a violent fit of sneezing. The sight of the eye was not lost, but he became very near-sighted. He was seen by Dr. Grasemann soon after the accident, and by his advice he consulted me. The lens was distinctly seen in the anterior chamber, and had a most brilliant appearance. I recommended the pupil to be dilated by atropine, and the patient to remain quiet in the recumbent position ; however, as he was in no pain and suffered no inconvenience, he would not consent to the confinement. On the 2Gth of April, inflammation set in, with photophobia, and the night was one of most intense suffering, so much so that he made an attempt to jump out of the window. Leeches were applied to the temple, morphia given in large doses, and subsequently chloroform administered, but without any alleviation of the extreme pain. On the 27th, nine days after the accident, he was ad- mitted into the Royal Westminster Ophthalmic Hospital, when I ex- tracted the lens, under chloroform. The extraction was made through a small section in the cornea, and was done under somewhat disadvan- tageous circumstances, as the angesthetic had already produced very alarming symptoms. At seven P.M. he was comfortable and free from pain. April 2 8th. — Had a good night without the administration of an opiate. 29th, — Still remains easy and free from pain. 30th. — Did not pass quite so good a night, but on the whole he was going on well. May 4th. — To-day the eye was opened, and found to be progressing favourably. 1 1 th. — A small piece of the iris has cicatrized in the wound of the cornea. To be gently touched with the nitrate of silver. 13th. — Being very anxious to go out, he was discharged, and has quite recovered, with tolerable sight, requiring the usual convex glass. The lens, after extraction, was perfectly transparent, and apparently uninjured, except in form. When the eye was first examined — that is, two days after the accident — neither the vessels of the retina nor of the choroid were at all changed, or in any way congested. The lens in the anterior chamber pressing upon the iris, making a considerable concavity and acting as a foreign body, was the cause of the ciliary neurosis and torturing pain. " It should be mentioned," says my patient, " that both eyes were myopic, and more especially the right, which has been weak for several years ; " accordingly I determined to make a careful examination of that eye also, and at once discovered that the lens was absent. Complete displacement had taken place, though it 152 SUBJECTIVE OBSERAVTIONS IN was with some difficulty I assured myself of the fact. By placing the patient, however, in a reclining posture, the lens came into view, and then, by employing oblique light, both Dr. Grasemann and myself made out to our satisfaction that the lens was quite transparent and perfect. It may be as well to note that, until this examination wdth the ophthal- moscope, although he had been under the care of more than one ophthalmic surgeon in Germany, the displacement of the lens of the eye had not been suspected. Some details of vision under sucli circumstances will be interesting and new. As being the subjective observations of an intelligent man reporting upon his own case, I give in his own words what he aptly terms an analysis of his sight, and which he drew up for my information : — Nov. 1862. "After the lens of my left eye had been extracted by you, in April, 1860, I made use of a pair of spectacles with convex glasses for reading and writing, of equal strength for both eyes, although the lens of the right eye still remained. For distant sight I made use of a second con- vex glass before the right eye, which was much assisted by the use of these glasses, as well in regard to clearness as to distance. During the latter part of the summer of 1 860, 1 observed that I could no longer see so well through the glasses with my right eye ; the glass of the specta- cles in front of it seemed to have some dark spots upon it, which im- peded vision, whereas other spots allowed me to see more clearly. I began to clean the glasses, but as all my endeavours were in vain, I changed them for others, but obtained no relief. Soon afterwards I could distinguish nothing with my right eye by the aid of spectacles and a lorgnette that I used at times. Then again it very soon began to gain its natural power of vision, so that I was enabled to read at a greater distance without spectacles than I had ever before been able to accom- plish with or without spectacles. This appeared to me to be the conse- quence of over -excitement. Soon afterwards, this increased power of vision became interrupted, and I frequently saw objects double and triple, especially if at some distance off. This Avas again obviated by using the lorgnette with a convex glass before the right eye, but only for a short period. In November, 1860, an inflammation attacked this eye, which nearly deprived it of vision. By the use of warm fomenta- tions, aperients, and iodine, the inflammation was at length arrested, and A CASE OF DISPLACED LENS. 153 I \va3 again able to see — but, without the aid of spectacles, worse than ever ; and with them, rather clearer than before. One day, whilst attempting to use my lorgnette, I was much surprised to find that I could see most remarkably clear with it. Nevertheless, I was very much annoyed by a very disagreeable appearance before my right eye, which has since continued. Whenever I lie down upon my back or stoop my head, a figure of an oval shape with a dark centre appears before my eye,* i?Ae whole presenting the picture of the eye with the eye- hall. This figure sinks from above downwards, and seems to float before the middle of the eye : it is transparent, and allows the right eye, when it is obliged to look through it, to see clearer than through a lorgnette. This vision troubles me more or less, as my health is better or worse. It seems to me, that this transparent figure has by degrees obtained a somewhat darker colour. As long as I look straight forward I do not observe it. I even now see rather better with my right eye than with my left, and can recognize all objects at a given distance without glasses ; but I still want a clearness of outline, and especially when I do not feel quite well, or after exerting my eyes too much ; ob- jects, as human faces, appear to me to have taken another form. For about six months I have also observed that the pupil of my right eye has become much smaller, which has interfered with my vision. The use of belladonna always gives me great relief, and the day after its use I see things in their true and natural form." March 8th, 1863. — This patient applied again this day, the lens having accidentally passed into the anterior chamber, whilst stooping. Upon dilating the pupil, and placing him in the horizontal position, jt went back without giving him further annoyance, and only a very slight degree of pain. Still more recently a case came under my care , where a displacement of both lenses occurred in a child, the result of severe fits of whooping cough. The patient, J. A , a boy, five years old, whose father had died of consumption. The mother also was exceedingly delicate. The child had suffered from a succession of infantile diseases, the whooping cough * The lens rising up and occupying the pupillary aperture wonld prodncc this appearance. 154 DETACHED RETINA, having supervened upon an attack of measles. His sight, always weak, now failed him so much that he could only distinguish large objects, and those in a strong light; he was continually running against the chairs and tables. In general appearance the little patient was de- cidedly strumous, small in stature, the legs bent and generally deficient in bony material, the teeth being decayed and deficient. A careful ex- amination proved that the lens of the right eye was displaced, without doubt displaced by the violence of the cough, which usually produced bleeding of the nose. In the left eye, still further mischief had resulted : the lens had in all probability been dissolved, as no trace of it could be seen after a most careful search ; a portion of the retina had also become detached. That a very severe injury to the eye, accompanied with dislocation of the lens, sometimes occiu's, with a singular fa- cility of reaction in the parts, which might suggest the ordinary l^henomenon of healing by the first intention, is evident from the following case : — Jane S , aged 46, applied for relief July 16th, 1862. She states, two days ago she received a blow from her husband with a can- dlestick, and found herself suddenly deprived of sight, attended with considerable pain and uneasiness, for which she was recommended poultices. The left eye is softer to the touch than the right, and rather swollen at the inner canthus ; the cornea is transparent ; the iris irregular and dilated ; the lens can be seen moving in the vitreous humour ; it is still transparent, and admits of the retinal vessels being observed ; they appear to have lost their outline, from an effusion of blood, which is floating about in patches ; the optic nerve is also observed to be covered by a clot. Ordered : Pil. hyd. cum opio. om. noct., and aperient draughts ; to apply three leeches, and use warm fomenta- tions. On the 2ord, much better ; vision in a great measure restored to right eye. In a fortnight this patient recovered sight in the right eye, and partially in the left, when she left the hospital. Cases such as the following cannot in future occur, with the ready means now possessed of detecting displacement of the lens. Immediate action, after first symptoms have subsided, must be taken to remove the lens, with eveiy pro- AND DISLOCATION OF LENS. 155 bability of saving the sight of the injured eye. All the evils arising from sympathetic irritation extending to the other eye will also be obviated or prevented. Dislocation of lens into anterior chamber ; sympathetic irrita- tion of opjyosite eye. — W. A , aged GO, a mason, admitted Aug. 29th, 1861. Injured the left eye with a lath 35 years ago. No doubt at this time the lens was displaced by the blow ; for, immediately after, he suffered from severe inflammation of the eye, and when he recovered, could barely tell light from darkness. About six months later, some lime fell into the eye ; although this did not give him much pain, he has since been perfectly blind. For the last ten or twelve years, a hard yellowish-looking lens has been lying against the cornea. In front of the lens, and as if adherent to the cornea, is some cretaceous - looking deposit. Pupil dilated and fixed. Retinal vessels of opposite eye congested, and sight much impaired. Aug 30th. — I extracted the lens by the upper section ; it was ad- herent to the cornea, and some adhering portions were with difficulty scraped off. Sept. 1st — Pain less ; no swelling. 7th — General health im- proving. Gutt. Atrop. : Mist. Ammon. c Cinchon. 11th — Discharged. Vision improving. DISEASES OF THE RETINA. lletinitis, acute mid chronic — Hypercemia — Congest ion — Apo- plexy, simple and complicated, with Retinitis Pigmentosa, Albuminuria, and Syj^hilitic Disease — Effusion, (Edema, De- tached Retina, Anmmia, Hemeralopia, Nyctalopia, Hemiopia, and Asthenopia. Now that the ophthalmoscope gives such sufficient oppor- tunity of distinguishing between functional disturbance of vision due to general and remote causes, and those positive objective appearances by which local disease may be almost unmistakeably known, the necessity has arisen for a com- plete revision of ophthalmic nomenclature, with corres- 156 CONDITION OF RETINA pondiug distinctuess of definition, so that totally different diseases may not be confounded together, as was formerly too apt to be the case. This may be especially observed of a large class of symptoms which formerly occupied so much of the attention of surgeons under the vague and indefinite term of amaurosis, and of which one distinguished practitioner in eye disease has observed, " both the patient and the doctor were blind." "Without attempting, however, the arduous task of taking up the several varieties of amaurosis which have been invented to meet the extraordinary nature of the various cases Avhich were classed under this head — or endeavouring to reconcile a few of the more prominent and persistent symp- toms with specific appearances in the ophthalmoscope, for the purpose of perpetuating what can only be now considered a superseded term — I have sought to base my remarks upon the principle of connecting with the name of the chief seat of the objective symptoms the usual aflixes indicative of inflamma- tion, congestion, &c. The use of the tongue in determining the condition of the stomach is not more available now, than the corresponding resource in affections of the brain which the possession of the ophthalmoscope affords. The different phases of congestion, from the first sense of fulness, weight or heat in the eyes after exertion, to the more distressing s}Tnptoms of retinitis, appears to me a wide field for fui'ther observations in this direction. As has been justly observed by Mr. Swan,* " In diseases the retina sympathises directly] with the brain through the visual track producing either an increased sus- ceptibility from excitement, or a dulness from debility and oppression. It sympathises through the involuntary tract wdth the par vagum in disorders of the lungs or stomach, and in a less degi^ee with the par vagum in disorders of the heart and part of the intestines which are more fuUy suppHed by the sympathetic nerve. It sympathises with the sensitive Swan ' On the Visual Powers of the Optic Xerve.' A MEANS OF DIAGNOSIS. 157 tract through the sentient nerves in disorders of the skin and conjunctiva. It sympathises least of all with the parts chiefly supplied by the sympathetic nerve, and, only, through the filaments of this nerve given to the ocular artery in com- mon with the rest of the internal carotid supplying the brain."* Before exact knowledge was possible, retinitis or inflam- mation of the retina was a matter of very difficult diagnosis ; and the very different descriptions of the disease given by various writers were accordingly a source of much inconveni- ence, especially to young practitioners. And, at first sight, some embarrassment may still arise, unless great care is taken to distinguish between the appearances of increased vascu- larity in the retina, and the choroid with which it is so closely associated. In the former, however, the opacity induced is more general, and of a misty foggy-looking pinkish grey, through which the small blood-vessels of a deeper red are indistinctly perceptible. The periphery of the optic nerve becomes ill defined, and the central vessels enlarged, the veins especially so ; nevertheless, their course is traced with difficulty. It may be also observed, as useful, that in eyes with a scanty pigmental deposit this opacity is not so well discerned as where the fundus presents a comparatively dark ground. Sometimes the loss of trans- parency may be traced to serous transudation into the vitreous humour. In choroiditis, the effusion would be under the * "A man possessed of a sound mind in a healthy body, endowed with organs of sense of perfect construction, and lieeping in all things within the bounds of temperance and moderation, would be absolutely free from illusions and hallucinations. His eye would present to him none but real sights ; his ear would convey to him only real sounds. His sleep would not be disturbed by dreams. The only sensations not exactly corresponding to external objects which he would experience, would consist in the substitution of the complementary colours for each other, if he fatigued the eye by fixing it too long on some bright o1)ject. The golden sun would appear to his closed eyes like a violet-coloured wafer ; a window frame would seem to have dark panes and light sashes, and a dark picture with a gilt frame would have its light and dark fcatm-es transposed." 158 RETINITIS. retina, lifting it up in distinct patches. When the capillaries of the retina are ruptured, owing to over distension, the usually hsemorrhagic points are also visible. Sometimes, when the case has become chronic, deposits upon the choroid can be discerned, of a peculiar character, as a narrow zone of a whitish colour surrounding a central spot of a pearly- lustre. When the optic nerve entrance is undistinguishable from the rest of the fundus, its position is best determined by the point of exit of the larger veins. Serous effusion often takes place when retinitis occurs in connection with a syphi- litic disease, or in strumous habits. The earhest symptom of the disease is a gradual loss of sight; this increases until objects are recognized only with difficulty. The pain accom- panying the inflammatory stage may not be sufficient to direct the patient's attention to the threatened mischief; so that the excessive photophobia and photopsia, upon which much reliance was formerly placed, is now known to be of little value or assistance in our diagnosis of retinitis. Retinitis. — J. B , aged 34, a clerk, admitted Sept. 6th, 1855. First noticed a remarkable reflection of the gas in church ; saw two dis- tinct rows about a quarter of a yard from each other. Upon making a further effort, found he could not see to read with the left eye ; there was a mist immediately over the spot he looked at, and the lines, instead of appearing straight, were zigzag, and every upright object di- verged from the perpendicular to the right; thus the sight became gradually more and more indistinct, until at last he could only discern large objects. He was iTiore or less troubled with flashes of fire. Ophthalmoscopic examination. — The central vessels of retina much congested, and optic disc nearly obscured by an apparently overhanging cloud or capillary web. Ordered Plummer's pill, five grains, every night ; and sulphate of magnesia, half an ounce, the following morning. This treatment was occasionally discontinued, and then again resumed. On the 20th of October, he said, " I can now see a considerable distance ; but every object appears to be in two places, the one not so distinct as the other. I cannot yet see to read other than very large print ; for instance, the heading of a newspaper. The lines are, how- ever, much straighter than formerly." At the end of another month, hyper;emia. 159 he reports of himself, " by a steady adherence to your plan of treatment, I am much improved, and able to return to my duty." Eeti7ii/ is. ^ohn W , aged 2G, a plumber, admitted Sept. 5, 1801. Always had good health and sight up to the commencement of the present year. He then received a blow on the forehead, and from that time his sight has been growing dim, especially that of the left eye, in which he first perceived a change. The right eye remained perfectly good until March, when, after the application of a few leeches to the left temple, vision in this has been gradually getting weaker ; and, later, flashes of fire, with considerable pain in the head. The globes are hard to the touch ; pupils slightly dilated and inactive. With the right eye he can only count fingers and make out a few letters, No. 20 type-tests ; with left he cannot do this — even No. 20 is seen as a black patch. With ophthalmoscope the fundus is seen to be dotted over with very red spots of blood ; a dark crescentic ring nearly surrounds the optic nerve ; the vessels are distended, but very ill defined. As the treat- ment he had been the subject of during a greater part of ten months had effected so little for him, I resolved, first to try division of the ciliary muscle, for the relief of a considerable intra-ocular pressure, and after- wards a mild course of mercury. On Sept. 6th, I divided the ciliary muscle in both eyes. On the 16th, the mercury was changed for iron. Four days later, he was able to read No.l2 type-tests, and became an out-patient. Great relief to all his symptoms, with amendment of sight, took place in a month from the time of his admission. Hypersemia of the retina is a disease very frequently met with among persons engaged in occupations requir- ing constant and close use of the eye on small objects, such as engravers, jewellers, watchmakers, &c. who for the most part become presbyopic at a comparatively early age. The earliest inconvenience arises from a sense of heaviness in the eyes, with dimness of the sight, an oppressive fulness in the brain, and flushing heats over the scalp and face. At first, these are reheved by temporary rest, but only to return on resuming work. The ophthalmoscope reveals distension of the blood-vessels, the cajiillaries being enlarged, and the cii'culation through them impeded. The congested condition of the retinal papilla is perhaps due to the direct compression 160 CAUSES OF HYPER^^MIA. of the veins by a corresponding condition of the vessels of the choroid. These appearances give way to proper measures of relief, as perfect rest to the eyes, &c. Some consider hyper- semia explained by the fatigue of the powers of accommoda- tion occasioned by the continued effort of the ciliary muscle to shorten the visual focus. The second variety of hypersemia is most commonly met with in adult age, where the system has become debilitated by long-continued abuse of tobacco and alcoholic stimulants, and illustrates how naturally the fundus of the eye assumes conditions indicative of the general state of the body. The patients present the usual symptoms of incipient cerebral disorganization, in the tremulous movements of their tongue and general appearances. Here, on examination, "wdll be found congestion much more considerable extending over the retinal field, and concealing in a great measure the papilla by a uniform deep red hue. When the optic nerve entrance is thus undistinguishable from the rest of the fundus, the course of the vessels Avhich are still visible enables its situation to be made out. I have met with many cases of hypersemia arising from over-work of the organ, exposure to cold and fatigue, and also from concussions produced by falls or blows, accompanied by some slight amount of cerebral disturbance. The ophthal- moscope reveals the slightest degree of effused blood, and we can watch day by day its gradual absorption, and the restor- ation of suspended vision. HyperEemia is usually character- ised by increased vascularity, chiefly arising from the capillary injection over the optic disc, and a greater degree of venous congestion, which rapidly produces loss of transparency in the retinal membrane and vitreous humour. When these changes are associated with capillary haemorrhages, then I consider the case is one of apoplexy of the retina, and consequently of a more serious character, often ending in disorganization of the retina. A good example of the simplest form of h^^Dcrsemia occurred in a shepherd lately under my care. He was much exposed during the cold nights watching his flock ; at the IIYPEKiEMIA IN YOUNG PERSONS. Il>l same time his food was insufficient in quality and quantity. His first annoyance arose from an inability to count liis sheep : this was soon followed hy more alarming symptoms, for he could no longer see them, and had great difficulty in finding his way home. There was little or no pain, and when sent up to the hospital, the vascuLir distension was consideral)le over the whole fundus. Under good diet, nursing, alteratives, and tonics, in about a fortnight he was discharged, cured. Hyperremia frequently occurs in young persons ; among schoolboys I have met with several cases. Master M.- B , aged 12, a fair delicate ■ looking boy, not very robust, after long fatiguing play, came home complaining of dimness of sight. Next day he was unable to read his lessons ; but as there was no objective sign indicative of any change in the eyes, his statement was discredited, and little or nothing was done for a week or more, when the boy's state became more alarming, and the medical attendant recommended the master to bring him to me. He could only see the largest of Jager's test-types, there was great uncertainty in his walk, with an evident dragging of one leg. On examination with the ophthal- moscope, I found hypersemia affecting both eyes. My treatment con- sisted in rest, alteratives, iron, and counter-irritation. I saw him again in a fortnight ; he was then improving, and could read No. 1 2 test- types ; and at the end of a month, the retina was restored to health, and he has since remained perfectly well. Master H , aged nine, a delicate -looking boy, with a fair com- plexion, during a railway journey kept his head a good deal out of win- dow of the carriage : when he got home he complained of being unable to see. He tried to read, but found all the letters running into each other ; he could only make out a part of very large type. Kxcept a slight strabismus in one eye, and somewhat dilated state of the pupils, nothing could be made cut of his case, and, therefore, a little opening medicine was given the first week. The boy still persisting in his first statement, his friends brought him to me. The hj'peraimia here was very considerable ; under a similar kind of treatment as that adopted in the former case, he quite recovered. I could multiply these cases, and quote numerous exam- ples, with some slight variations, more especially occurring, M 162 CHRONIC RETINITIS, I would observe, among children of the poor : hut, as my object is to direct attention more to a class of cases which have been quite unintelligible, and must have remained so without the aid of the ophthalmoscoi^e, I content myself with the recital of a few well-marked instances. Qhronic Retinitis. — In chronic retinitis, the symptoms are of the same character as in hypersemia, but more strongly marked. The uneasiness and aching in the eye are much more troublesome; frequently the pain is severe; in many cases there is violent headache. The vision has lost its clearness; small or distant objects, in particular, are no longer sharply defined. The field of vision is sometimes en- croached upon in various directions. Light is unpleasant, and the patient finds comfort in the shade. The sight fluc- tuates much and rapidly ; sometimes it is lost altogether for a few minutes. Most patients complain of a haze or fog before the eyes, which may increase in density until the sight is destroyed. In some, any sudden concussion of the body — as that produced, for instance, by stumbling, coughing, or sneez- ing — produces flashes of light, as if the eyes had received a blow; others see brightly-coloured spectra, in the form of rings, spots, &c. For my o^\ai part, I look upon this disease as one, more of a recurrent, than a chronic character ; it is also very often complicated by some change in the choroid coat, and exudation between the two membranes. OjM.hahnoscojnc Appearances. — At the first glance, we see that the optic nerve is not in a normal condition, and that the fundus of the eye in its immediate neighbourhood has undergone some change in colour. In very slight cases, a portion of the margin of the disc is concealed by a fasciculus of vessels. In more advanced cases, one-haK or more of the papilla may be concealed ; in confirmed cases, the whole of the papilla is so covered that it requires some attention to make it out. The situation can always be discovered by the converging point of the central veins and arteries, which re- tain their distinctness, although it is frequently very difficult to trace any part of its circumference. The retina may preserve APPEARANCES AND CASES. 1G3 its natural appearance, but occasionally we find an ill-defined spot, in which the colour has become somewhat changed and brightened, the hue being yellowish red, with a slight glaze of a bluish or greenish tint. The region about the macula lutea is generally very red. Chronic Retinitis. — Thomas R , aged 29, dissenting minister. Two years ago, a speck appeared in each eye, and so annoyed him that he was obHged to consult a medical man, who pronounced it inci- pient cataract ; not feeling satisfied, he was induced to go to a homoeopath, who had him under his care for three months ; but not the slightest benefit resulted. He was subsequently blistered and sub- jected to other treatment ; still his sight became worse, and he was then sent to me. At the time, September, 1857, his general health was good, with the exception of occasional headaches. Examined with ophthalmoscope. — In right eye a few very slight bands of lymph adherent in the anterior chamber, partial synechia ; this eye he believes " to have been much inflamed during first attack, two years ago." Vessels of retina obscured by a dark-red spot surrounded by a greyish ring. The lefl is rather paler ; has also a red cloud surrounded by a ring, and tortuous and congested vessels. The pupil of the lefl eye is dilated. In this case the congestion gave a greyish opaque appearance to the lenses ; the patient experienced much relief from attention to his general health, with improved diet, rest to the eyes and over-worked brain. On the 27tli of January, 1858, he thus writes to me : — " I have been compelled to leave London to attend to my ministerial duties ; but during the time I was under your treat- ment my eyes improved so much that I am quite sure, if I could have remained near you, they would have continued to improve, and perhaps by this time been quite well ; nevertheless, I am able to pursue my avocation." Chronic Retinitis. — A. B , aged 29, law-clerk, a thin, tall, pale-looking, nervous man, applied to me June 29th, complaining of in- sensibility of retina of the left eye. During several months past, his eye has given him pain and annoyance ; at present time he cannot see to read or wi'ite with it ; general health tolerably good ; but frequently suffers fi'om bilious attacks. The iris of left eye slightly changed in colour ; the lens by daylight appears 0})aque ; but upon making an examination with the ophthalmoscope, it was seen to' be perfectly clear, the colour M 2 164 CHRONIC RETINITIS. being evidently due to congestion behind the lens. The vessels of the retina irregular, and so much congested as to conceal the entrance of the optic nerve ; slight serous effusion betv^een choroid and retina. Pil. Hy- drargyri with aperients were ordered continuously. Under this treatment he improved ; tonics were then prescribed for a fortnight, and at the end of a month he was able to resume his occupation. These cases illustrate the value of the ophthalmoscope in deciding the question of opacity of the lens, thereby enabling us at once to direct attention to the seat of disease ; hence the favourable results. I have lately seen this last- mentioned patient, who has had no return of the affection. He has, however, strictly followed the advice given him as re- gards rest to the eyes and attention to his general health. Chronic Retinitis, from an old apoplexy. — E. V , aged 81, states that in his left eye he has three or four deep brown scales, and one much larger than the rest. They are enclosed in circles by day, and at night resemble spots and a network of blood ; occasionally long streams of light flash over the sight. Believes the disease was produced by a blow on the temple about seventeen years ago, for which cupping, leeching, and salivation were resorted to, but did not quite re- move the dimness of vision. With the ophthalmoscope the retinal vessels of left eye are seen to be much congested ; these give off a cir- cular zone of vessels, which mask the entrance of the optic nerve. In the right eye there is less congestion ; but many vessels run over the entrance of the optic nerve, and are no doubt the cause of the web-hke appearance complained of. Small doses of Hyd. cum Greta at night, and a mixture of Ferri. Cit. with Quinine and Sulphate of Magnesia twice a day, were prescribed, and regularly taken for three months. I then ex- amined his eyes, and found the congestion had considerably diminished, and the entrance of the optic nerve, with its vessels, was in a healthier state : he was aide to resume his former occupation. Dr. Anagnostakis relates of one : " Beillaud, a book- keeper, aged 42, of a sanguineous habit, who, during recovery from an attack of dysentery, experienced, without any known cause, a remarkable weakness of sight ; at the end of a month the left eye could scarcely distinguish day from night. With APOPLEXY OF RETINA. 165 the exception of a greenish opacity, a slight dilatation of the pupil, and some injection of the conjunctival vessels, there were no other symi^toms to account for tlie blindness. The ophthalmoscope revealed congestion of the vessels of the retina, with many small hocmorrhagic patches of different shades of colour distributed over the retina." In several cases of congestive amblyopia, wiiich came under the care of Dr. Anagnostakis, as well as in a few ad- vanced cases, in which the eyes presented a peculiar glauco- matous appearance, he observed blood effused beneath the retina ; in other cases, hypersemia of the retina was the only alteration he could positively make out, and in no instance was there any change in the crystalline, or vitreous body. Apoplexij of Retina.. The constant association of a critical phenomenon affect- ing the fundus of the eye, with a general epileptic seizure in the system, and producing the ophthalmoscopic appearances of congestion, rupture of small blood-vessels and slight opacity in the retina, would warrant the supposition that a premoni- tory stage exists, advantage of which might be taken to arrest the progress of the constitutional evil, if means were taken to discover its existence by an early examination of the eyes- Loss of vision mostly confined to one eye is associated with other symptoms of paralysis affecting the same side of the body, and is occasionally seen in the plethoric as well as in the ana3mic subject ; the local cu-culation being affected in one case with positive, in the other with relative, plethora. The loss of sight is frequently preceded by some kind of fit, or confusion of the senses, of which the patient has retained a very imperfect recollection, and therefore can give no very satisfactory account of the attack. In some cases which have come under my observation, the symptoms have given so small an amount of inconvenience and uneasiness, that, but for the loss of vision and ptosis, these persons, in all proba- 166 APOPLEXY OF RETEN'A, bility, would not have placed themselves under medical treat- ment. In apoplectic or paralytic ptosis, the orbicularis palpebrarum, preserving its power, keeps the eyelid con- stantly closed, so that the patient can see nothing unless he raises the hd with his finger ; when he does, he sees every- thing around him double ; and if he tries to walk, he is imme- diately afi'ected with an amount of vertigo that may cause him to fall to the ground. Upon raising the lid, the pupil is seen to be fully dilated, or much more dilated than that of its fellow. This is associated with an amount of obscuration of vision varying in kind and degree with the extent of the retinal hsemorrhage. Dr. Bro-^Ti Sequard writes — " But few persons are aware how completely certain cases of paralysis, from alterations of the blood, may resemble the paralysis due to an organic dis- ease of the brain. I have seen several cases of paralysis of most muscles of the body accompanied with symptoms of an organic afi'ection of the brain, such as ptosis, diplopia, ambly- opia, giddiness, loss of speech, occasional deliiium, loss of memory, &c. ; in other words, such a group of symptoms, that, had not proper care been taken, a mistake of diagnosis would have been made. The influence of the treatment in those cases confirmed my view of the nature of the afi'ection, and the patients were cured or much benefited by iron, qui- nine, strychnine, ammonia, cod-Kver oil, wine, cold douche on the spme, shampooing, and other means of tonic treatment. The many causes of alteration in the quantity and quality of blood, such as dysentery, typhoid fever, measles, scarlet fever, diphtheria, albuminuria, intermittent fever, &c. are all able to produce paralysis ; and, as a general rule, the paralysis, owing to an alteration in the blood, extends to the muscles of the trunk and limbs." The ophthalmoscope shows a considerable amount of capillary congestion, which nearly hides the optic disc from view ; the fundus is studded with clots, and it is in vain to expect to see the ruptured vessel. The only guide we have, and whereby we are enabled to say whether the effusion be APPEARANCES AND CASES. 167 recent or otherwise, is the colour. We can distinguish the crimson colour of fresh blood from the older apoplectic clots, which closely resemble the dark colour of venous blood ; or, from having become rusty, leave dark, ha3matine stains in the meshes of the retina. The most noteworthy part of the treatment in such cases is the speedy relief of the more urgent symptoms by the division of the ciliary muscle, espe- cially when effused blood is seen in the vitreous humour, or making its way towards the anterior chamber. The pressure on the retina is at once relieved. Apoplexy of the retina; clot covering the macula lutea.' — ]\Iargaret A , aged 39, admitted August, 1862. On the Monday previously to applying, had fallen asleep after several days' suffering with headache and giddiness. Upon being suddenly roused, she found the sight of the right eye completely gone, and could not distinguish daylight. Had three attacks of paralysis when a child, and is still unable to use the right leg, which she drags after her, and requires a stick. Has had no attack since she attained womanhood. Two years ago, lost her mother suddenly, and has suffered much from domestic troubles and bad health. The ophthalmoscope shows a large number of extravasated clots of blood over the fundus, and one in particular covers the macula lutea. The vision of the left eye is also dim, and she cannot see to read medium ty[3es. The treatment consisted of small doses of calomel, with iodide of potassium, and a seton in the temple. In a few days the mouth became tender from the calomel, and she was obliged to discontinue taking it. Sept. 6th. — J\Iouth still affected. Sight of right eye very materially improved ; can distinguish faces, but unable to read, even largest type. 26th. — Sight improving ; can now see large tj^e. Last report, M. A. is making slow but steady progress. Retinal Apoplexy ; Ptosis and Paralysis of same side. — William C , aged 31, mariner, after long exposure at sea, in the beginning of 1861, was seized with pain and numbness down the right side. This continued for some weeks, when, after a sudden unconsciousness of everything around, which appeared to him to last but for a few minutes, there remained considerable pain on the right side of the head, and he 1G8 APOPLEXY OF RETINA, found he had lost the power of raising the right eyelid ; he saw douVjle, and his vision was much confused and very imperfect. As soon as he landed, he made his way to the Royal Westminster Ophthalmic Hos- pital. He was in a low state of health, pulse weak, which he said arose fi'om salt food and long exposure during bad weather at sea. He had still numl^ness in his arm and leg, with some di'agging of the latter. When the eyelid was forcibly raised, the pupil was seen to be dilated to the fullest extent, and directed outwards. The ophthalmo- scope showed a number of apoplectic clots in the meshes of the retina, considerable capillary congestion covering the optic disc, and a few floating masses in the vitreous. The eyeball appeared harder to the touch than its fellow. The treatment consisted in good diet, and small doses of Hyd. cum quina, with Mistura ferri sulph. At the end of three months he was able to resume his occupation, having nearly regained the muscular power of the eyelid and limbs, and vision was much improved. Retinal Aip^plexy ; Ptosis of Right Eye ; Partial Paralysis of same side. — William M , aged 38, labourer, had an attack of rheumatism after working in damp and wet ; this was followed by a fit, and he was taken to a general hospital. Four months afterwards he had another fit, and found he could not lift his right hand, nor open his right eye. When he applied for advice, the numbness of the limb remained ; could not protrude the tongue ^vithout it turning to the right side ; upon raising the eyelid, there appeared a slight external strabismus, and fully-dilated pupil. Vision almost lost ; could scarcely distinguish the daylight. Pulse small ; in a low state of health ; apo- plectic clots cover more than half of the optic disc ; retina much congested ; vision in left eye imperfect ; can read only large t^^e. After having this man three weeks under treatment as an out-patient, and finding he did not improve, I admitted him into the hospital. He was put on full diet at once ; and this, together with warmth and a comfortable bed, to which he had not been accustomed, and a mix- ture of iodide of potash in dec. cinchonae, in three weeks restored the muscular power of the eye: he can now read No. 12 test-ty|5es at 18 inches, and grasps the hand fii-mly. Good food and rest no doubt effected as much in this case as medical treatment. Apoplexy of Retina ; Ptosis of Right Eye, avd slight general Paralysis. — Jolm D , aged 33, a carman, generally enjoyed a fair wrrn partial paralysis. 109 amount of good lieLilth, although exposed a great many hours to the cold in his daily occupation. About three months before, suffered a good deal from pain across the forehead; this was followed by dimness of sight, which however passed away. The day previous to his admission, he was driving in the city, when he felt a numbness m all his liniljs ; his sight became suddenly dim, and he was obliged to give up the reins to a youth who was with him at the time. The right eyelid immediately became closed, and when he got home he could not find his vray about. This was accompanied by much pain over the brow, and great inal)ility to raise his arms and walk about, and protrude the tongue. On the following day, a good deal of the paralysis had disappeared, and he was brought to the hospital ; the ptosis and dimness of sight were about the same. Upon raising the right eyelid, the pupil was seen to be com- pletely dilated, and the fundus much obscured by apoplectic clots ; the left eye shared in the congestion, although with this he could read the largest test-types. The treatment consisted in giving small doses of Hyd. cum quina every night, with the iodide of potass and bark mixture three times a- day. Full diet, warmth and rest. At the end of two months, he perfectly recovered his health, his sight being quite restored. Apoplexy of Retina ; Ptosis of Left Eye ; Partial Paralysis. — Henry H , aged 84, a shoemaker ; a pale-faced, sickly-looking man ; has had several slight paralytic fits ; lives irregularly, and can- not afford to eat meat often. Was treated for the fit in a general hos- pital, and regained the use of his limbs ; but the ptosis of left eye remains the same. He has no power over any of the muscles of the eye ; it, therefore, remains immoveable, and directed slightly outwards. The pupil is fully dilated ; a few apoplectic clots seen distributed over the fundus, as weU as in the meshes of the retina, with considerable capillary congestion. The optic disc appears to be whiter and larger than in the normal eye. The treatment adopted in this case has been counter-irritation, with strychnine, iron, and quinine. He has been a little more than a month under treatment ; but no great amount of improvement has as yet taken place. We here lack the good and suf- ficient food required to second the efforts of medical aid. With the gradual absorption of the efiused blood, a corres- ponding restoration of vision is expected; otherwise the "case becomes chronic ; we have then remaining partial insensibility 170 APOPLEXY OF RETINA, of retina, and a form of disease which has been termed by some, retinitis pigmentosa, the fundus retaining its confused patchy appearance, having dark-coloured masses entangled in the retina, as well as in the vitreous humour. The sudden loss of vision, the dilated pupil, the special and general paralysis, are so many well-marked symptoms of paralysis due to alteration in the quahty or quantity of blood ; and, assisted by the ophthalmoscope, there cannot now be much danger in confounding such cases mth those arising from an irritation of certain parts of the cerebellum, acting upon some portion of the nervous apparatus of vision, and thus producing paralysis of the retina. The cases narrated are not selected, but taken casually from among numerous others, the same in their general characters, and go far to show that " disease is in all cases not a positive existence, but a negation ; not a new excess of action, but a deficiency ; not a manifestation of life, but partial death ; and, therefore, that the business of the physician is, directly or indirectly, not to take away material, but to add ; not to dimmish function, but to give it play ; not to weaken Hfe, but to renew lifeJ^ Retinal Apoplexy, from Kidney Disease. The interstitial substance of the retina, formerly beHeved to be nervous fibres, is now known to consist of a highly de- veloped connective tissue, which supports the grey nervous layer and its delicate capillary system. It is in this connec- tive tissue that, in albuminuria retinitis, fatty degeneration is first developed. A congestive stage of the vessels of the retina leads to minute extravasations, which become centres of induration. These seem to follow some order of progres- sive production, as the patches gradually enlarge, with a disposition to form an elevated zone round the optic disc, as if due to some deposit or exudation beneath the retina. * Dr. T. E. Chambers, ' Medical Times,' Nov. 1861. WITH BRIGHT'S disease. 171 According to development, there is also a proportionate degree of insensibility to light, up to complete loss of vision. Other ai^pearances may be also frequently observed, such as the formation of large granular corpuscles, with a certain swelling up of the- nerve fibres, causing them to look like gan- glionic cells. The fatty degeneration will sometimes be found to extend to sclerosis of the choroidal vessels. At the beginning of 1861, a young lady, twenty years of age, came under my care, with unmistakeable symptoms of albuminuria ; but at that time I was unable to make out the characteristic changes in the retina. There was some congestion of the fundus with a slight hazi- ness, which gave a little appearance of muddiness to it. Although at tliis time the sight was not impaired, I perceived a small amount of effusion between the retina and the choroid in both eyes. Before she died, however, I had ample opportunities of noting the progress of the disease, as revealed by the effects upon the retina in such cases. The blood is so altered by the disorganization in the kidneys, which sepa- rates and discharges in the urine the albumen and red corpuscles, whilst the urea is conveyed into the system, that almost every organ suffers from this circulating poison ; but it is only in the retinae that the subsequent progressive changes of structure are visible. Ten days before the death of this patient, she saw with difficulty, and at length could scarcely distinguish night from day. (See fig. 7, plate 2.) Another interesting case was that of Mr. U , aged sixty. The loss of vision was confined to the left eye. The disease of the kidneys had been diagnosed for upwards of two years. When he consulted me, the sight of the left eye was considered to be lost ; but by a course of medical treatment he regained about half vision ; for when he turned his head towards the left shoulder, he could see a dim outline of half my face, and large objects generally. At the time, however, he seemed to be progressing most favourably, an attack of hemiplegia suddenly car- ried him off. The first symptoms of the fatal attack were pain in the head, followed by slight twitching of the face and impediment of speech. After a few weeks' care and medical attention, these symptoms passed away — only, however, to be followed, in three or four weeks' time, by a more severe fit, depriving him entirely of the use of the left side. In- sensibility of retina, still confined to the one eye, was now complete ; the patient became comatose, and died in forty-eight hours. 172 APOPLEXY OF RETINA, The following cases are instructive, inasmuch as I was led to believe in the existence of albuminuria from the ophthal- moscopic appearances of the retinse. The value of such a means of diagnosis therefore cannot be estimated too highly, when the treatment depends so materially upon the nature of the constitutional disorder. Daniel F , aged forty, admitted August, 18G1, a gas-fitter, complained of very defective sight in both eyes. Had been rather a free liver, and twice under the influence of lead poison. For two years, had noticed sweUing of the legs ; but, as he felt no inconvenience, had neg- lected to attend to it, nor did he notice whether at the time he passed less urine than usual. About three months since, he suffered a great deal with headache, and had frequent calls to pass his water during the night ; the legs again swelling ; undoubtedly cedematous. Slight pain in the loins, urine scanty, albuminous and of low specific gi'avity. Ophthalmoscopic examination. — Pupils normal; numerous hse- morrhagic spots distributed over the fimdus, especially around the optic discs ; in the left eye more apparent than in the right. In- terspersed throughout were also observed several white patches, having a granular appearance and highly refractive, and which I pro- nounced to be fatty degeneration of the retina. The urine Avas sulj- jected to a closer examination, and found to contain albumen. A course of compound jalap powder, with preparations of iron, re-established the health of this patient, with improved vision, in two months after the date of his admission. (See fig. 10, plate 3.) John W ', aged 26, admitted September, 1861. Always en- joyed good health and sight until the previous Dec. when he received a blow over the left eye, and shortly afterwards dimness of sight com- menced, which chiefly annoyed him towards night. Three months ago, when his right eye first became affected, he went to a medical man, who leeched and blistered him ; but his sight getting worse, he applied at the Royal Westminster Ophthalmic Hospital, and was ad- mitted. The eyeballs were much harder than natural, and the pupils somewhat dilated and inactive. With the right eye can count fingers and place his finger on the largest test-types. With the left, the fingers and test-types appear like black patches. With the ophthalmoscope, the retina of each eye was seen to be covered with hfemorrhagic spots and white patches, especially around the optic discs. The retinal veins were WITH brioht's disease. 173 remarkably tinged, and dark in colour. With these indications, I was led to examine his urine, and found it of a very low specific gravity and albuminous, which directed the course of treatment. In this case, from the evident turgidity, and intra-ocular pressure which accompanied it, I was induced to divide the cihary muscle in both eyes, and had the satisfaction to find vision very much improved the third day after the operation. In about three weeks from the date of admission, he was able to read Nos. 10 and 12 test-types. Dr. R. Liebreich relates an interesting case of retinal apoplexy associated with Bright's disease, in the ' Archiv. fiir Oplithalmologie,' 1859. He gives likewise a summary of the diagnostic appearances to be looked for. "It commences with retinal hypersemia, the veins being fuller and more tortuous, becoming dark-red, and sharply outlined on the comparatively dulled retina. Blood, frequently in the form of radiating streaks, is deposited between the nerve- fibres, sometimes as oval or round spots, which still more ob- scure the vessels and fundus. The optic disc is ill-defined, appearing but faintly under the effused blood. Small white round elevated spots are subsequently seen in different parts of the fundus oculi; these increase in number around the optic disc ; there is, however, a greyish part of the retina left, somewhat circular in form, and rather larger than the optic disc. From its periphery, a thick, milk-white layer of granule cells is deposited and continued along the course pf the larger vessels. Later changes take place in the retina on the edges of the layer ; the granule cells do not appear in large white spots which have coalesced, but as groups of smaller ones, which arrange themselves peculiarly in the form of rays, while the middle of the macula lutea appears dark-red, contrasting with the white patches which surround it. In the normal parts of the retina, small ecchymoses soon take place, and more extensive extravasations cover a great part of the layers of fat, and transform the whole into a dark-red sui-face, or the retina becomes detached in its normal parts." Virchow regards the white patches of fatty degeneration described, as enlargements of the ganglionic cells, and not hy- 174 RETINAL APOPLEXY. pertrophy caused by fatty degeneration. Further microscopical research will alone decide this point ; in the meantime, when such appearances present themselves to the eye, we should he led to investigate the state of the heart and kidneys. Other German writers have given us rules wherehy this form of the disease may be the more readily dia- gnosed. It is said that " Retinal apoplexy arising from albuminuria may be distinguished from that produced by other causes. 1st. In apoplexy from albuminuria, the two retinse are commonly attacked at the same time, although in a more or less degree. In apoplexy dependent on other causes, one eye alone is generally affected. 2nd. In albumi- nuria, the effusion takes place around the optic papilla, in the form of a fan, but only rarely so in other cases, where also the effusion is situated at the lower part of the retina, behind or above the papilla. 3rd. In albuminuria, besides the apo- plectic clots, and the injection of the papilla, there is a marked muddiness of the whole central part of the retina, dependent on commencing fatty degeneration ; on the con- trary, when the apoplectic spots, although, perhaps, as numerous as those dependent on albuminuria, arise from another cause, the retina is transparent, even in their imme- diate neighbourhood. 4th. In albuminuria, most of the apoplectic spots are arranged along and close to the veins, and generally behind these vessels, so as to present a linear striated appearance. In other cases, ?m-connected with renal disease, the rupture of the vessels take place at their bifurcations, and the spot has a triangular or irregular form. 5th. A peculiar phenomenon is manifested, in retinal apo- plexy from kidney disease, in the whitening of the red patches at an advanced stage of the disease. In other cases, the fluid part of the blood is absorbed, and the spot may thus become of even a deeper tint than before." I have, however, seen several cases of symmetrical apoplexy of the retinse where no symptom of kidney disease existed. A case in point was also reported in the pages of the ' Medical Times ' last year. In this instance there was partial paralysis SYPHILITIC COMPLICATIONS. 175 of the left side, preceded by head symptoms, which were per- sistent. The urine was carefully examined, and found perfectly normal. Unfortunately the pupils were dilated by atropine be- fore their condition Avas noted. The ophthalmoscope showed a small apoplectic effusion just below the yellow spot in each eye. The above case supplies us with an interesting example of symmetrical extravasation of blood from the retinal vessels occurring with other symptoms of disturbed cerebral circula- tion. The following note is appended to the report : — "From these cases it appears there are two groups of cases in which retinal apoplexies are observed. In one, the effusions take place in connection with albuminuria, and are, perhaps, quite as nearly allied to purpuric ecchymoses as to those forms of hsemorrhages usually designated as apoplexies, and occurring in patients of all ages. In the other group, the retinal affection occurs coincidently with other indications of cerebral disturbances, in elderly people chiefly, and without any abnormal state of the kidneys co-existing. In these it is in all probability dependent upon disease of the coats of the vessels ; and the rupture, no doubt, occurs during a temporary congestion of the whole cerebral system, the pressure of which the weakened vessels of the retina are unable to sustain." Insensihilitij of Retina due to Sypliilitic Poison. It is now ascertained, with the ophthalmoscope, that where a defect of vision has accompanied or supervenes a syphilitic attack, the retina presents an unusually pale ansemic appear- ance, with irregular patches of exudation, fixed or loose flocculi, in the retina or vitreous. Frequently there is great intolerance of light, and a S(?nse of heaviness and pain in the globe of the eye. The retinal circulation shows evidence of considerable disturbance, as the vessels are observed fre- quently to be very unequally dilated. The most interesting cases of this class indicate serious complications in the cere- 176 STPniLITIC DISEASE. bral, or spinal system, paralysis in various fonns, especially paraplegia, being present ; and it is inferred that pressure, due to some abnormal condition connected with the disease, is the principal cause. There is a case on record of paraplegia originating in constitutional syphilis, "where a gelatinous tumour was found pressing upon the spinal cord. The pain that frequently accompanies attacks of this kind affords some indication of its exciting cause, as it comes on rather late at night, as from 11 p. m. to 2 a. m. Rheumatic pains come on earlier in the evening, and neuralgic usually occur in the morning. In this circumstance an important aid to diagnosis is obtained, which will assist in distinguishing between sy- philitic and other forms of retinal disease. A case of paraplegia from syphilitic poison, which oc- curred in the practice of M. Ricord, affords a very useful and interesting illustration ; and I therefore quote it, as an ex- treme case certainly, but also as including all the chief symp- toms and ophthalmoscopic appearances which mark retinal complication mth syphilitic disease. X , aged 30, of strong constitution and healthy family, con- tracted syphilis, with uidurated chancre in 1856, followed by secondary symptoms. These yielded to ordinary treatment ; but in 1858 there were mucous patches on the lips, alternately disappearing under mer- cury, and returning when treatment was suspended. Towards the end of 1858, he remarked increasing weakness of lower limbs, with difficulty of retaining urine. At the time he consuhed Ricord, there was general debility, syphilitic psoriasis, and evident paraplegia. He could hardly walk for ten or fifteen minutes. No abdominal tightness, constiijation, and retention of urine. Bladder and sphincter both partially paralysed. From two to four grains of iodide of mercury were given daily, inunc- tions and tonics were also exhibited. In six or seven weeks, power over the limbs and bladder had greatly increased. Some debility, however, re- mained during that year and the next. In April, 1860, the sight be- came dim, the pupils sluggish, and words appeared less obscured in what he was reading. On examination, the ophthalmoscope discovered cho- roiditis, and an effiision beneath the retina round the papilla, of a dirty- white colour, with an irregular margin. The mercurial treatment which INSENSIBILITY OF RETINA. 177 had been omitted during the last year was renewed, and the biniodide substituted for the iodide. In six weeks, vision became clear, and the ophthalmoscope proved the entire disappearance of the effusion. The power over limbs and bladder had been nearly restored, and by the end of the year the patient was quite well in every respect. The following case of amblyopia, arising from syphilitic taint, came under my care, and, perhaps, is remarkable from the absence of the more decidedly marked symptoms of chancre or bubo; the patient admitted, however, that when his sight first began to grow dim, eighteen months before, he was suffering from a neglected gonorrhoea. This case, as well as the next related, appears to have been associated with retinitis, or congestion of retina. E. R , aged 22, a carpenter. A very suspicious-looking copper- coloured eruption covers his body. A bright object like a star continu- ally floats before his eyes ; can scarcely see to work, and only read the largest letters on the side of an omnibus. General health not good. No headache, but some pain in the orbit. Eyes full and tense, and re- flected from the fundus an opalescent appearance. Examined with the ophthalmoscope. — Pupils contracted, and were therefore dilated with atropine. In the right eye, a small black spot covers the foramen centrale, the vessels of the retina are large, irregu- lar, and congested. In the lefl;, a similar fixed black spot ; but neither so large nor so well defined as hi the right eye. The peculiar opalescent reflection is due, no doubt, to congestion of retina. The patient was ordered a dose of grey powder every night, with an aperient draught the next morning. Under this treatment for a fort- night, vision improved considerably ; but as the eruption remained troublesome, a mixture was ordered, containing the usual doses of the biniodide of mercury in decoction of bark. The case steadily pro- gressed, and in a few weeks he was discharged cured, the peculiar reflection from the fundus having also entirely disappeared. Another case, nearly similar in all its symptoms, exhibited some variation of appearances in the ophthalmoscoj)e. W. H , aged 35, engmeer. About twelve months previously was living a very irregular life, and contracted gonorrhoea. His eyes N 178 SYPHILITIC NODE. at this time became affected with inflammation, since which his sight has been very dim and imperfect. First noticed the dimness in his left eye, and dark spots frequently appearing before vision. Subsequently the right eye became similarly affected. If he made any attempt to read, one letter seemed to run into the other. Had been obliged to give up his work in consequence of his sight failing him. The eyes are full and hard to the touch, with a greenish reflection from the fundus. Examined with ophthalmoscope. — Lenses perfectly clear ; fundus of right eye presents a deep red appearance ; vessels of retina large, and capillaries very numerous ; optic nerve of an irregular form, and studded with minute dark spots. Left eye, optic nerve oval in shape, a yellowish grey-coloured film covers the vessels ; choroid of a dull reddish colour ; and grey patches in vitreous. In this case, the bi- chloride of mercury in decoction of bark was prescriljed, from which he derived much benefit, and was enabled to resume work in two months from the date of his admission. I have had an instance of considerable swelling of the hone ahout the base of the orbit. The history of the case and certain nodular appearances, with a misty haziness of the re- tina and congestion, led me to diagnose the true character of the otherwise obscure symptoms, and unaccompanied by pain. The generally beneficial effect of small doses of mercury and the bromide of potash proved the connection of the retinal affection with syphilis. Such cases also confirm the sug- gestion of Mr. Hutchinson, that many of the recorded instances of amaurosis cured by a course of mercury, and which, before the introduction of the ophthalmoscope, were attributed to some thickening of the membranes of the brain, or some effusion pressing on the optic nerves, were perhaps really due to a syphilitic taint. Charlotte R , aged 29, admitted February mth, 1803. Has been living a very irregular life, and is now in bad health, and very weak. Had good sight until the previous November, when she was admitted into a general hospital, labouring under sy|ihilitic disease. With the left eye can only distinguish day from night, and the sight of right is very dim ; a good deal of pain comes on every night SYPHILITIC RKTINITIS. 179 about twelve o'clock, which prevents sleep. The globe is hard to the touch ; pupils fully dilated. Examined with the ophlhahnosope. — The fundus of the left eye exhibits a considerable amount of retinal disorganization ; peculiar white irregular patches surround the optic nerve, represented in fig. 6, plate 2. The right, although anaemic, bears evidence of having suf- fered from some hsemorrhagic effusion ; and numerous flakes were floating in the vitreous. She was put under a mercurial plan of treatment ; but as her constitution soon began to show signs of in- tolerance of the drug, it was changed for the iodide of potassium and the syrup of iodide of iron. An opiate was given every night at bed time. In six weeks the vision of the right eye began to improve, whilst that of the left was scarcely changed at all for the better at the end of two months. Still under treatment. Another instance where the defective vision was not sup- posed to be connected with a syphilitic taint, but in which the ophthalmoscopic appearances and the result of the treatment were fully confirmed by the history of the case, came under my notice lately. Mary W , aged 28, was a servant, and at the time of admis- sion in good general health. Suffered from syphilis about twelve months ago, but considered herself cured. Six months since, she noticed a dimness in the right eye, which gradually increased, and at length the left eye also became similarly affected with pain and partial loss of sight. The ophthalmoscopic appearances exhibited deposits upon the retina of a greyish colour, with floating bodies in the vitreous. In this case I observed a very apparent approach to the characteristic condition of the fundus in retinitis pigmentosa. The treatment con- sisted of small doses of mercury, followed by the bromide of potassium, and in three months she was discharged cured. Retinitis Leuccemia, produced by a secondary syphilitic tai?if. — " Eliza M , aged 86, a pale, feeble-looking woman, applied at the hospital, complaining that ibr months back her sight had been failing. She carried in her arms a stout baby, ten months old, and stated, on en- quiry, that it was her ninth, and lived almost solely upon the breast. She had suffered no pain whatever in her eyes, and there was not the slightest congestion of any part to be seen. The pupils were of mode- N 2 180 APPEARANCES OF FUNDUS. rate size, and freely mobile ; indeed, as far as the unassisted eye could discover, the ej'^es were perfectly normal. Her account was, that for four months the sight had been dim, as if smoke were before her eyes ; muscse volitantes liad also been troublesome. At no time had there been either pain or redness. She could still see large print, but not sufficiently well to read it ; and she could not tell the time by a large clock at the opposite side of the room. With such a history and such symptoms, could any one have been blamed for pronouncing the origin of the disease to be asthenia lactanieum, and ordering the woman to wean her baby, and take stout and quinine ? Five years ago, we question whether one surgeon in a thousand would have arrived at any other conclusion. It was deemed best, however, to employ the oph- thalmoscope before prescribing ; and with the light which that instru- ment threw upon it, the case assumed a totally different aspect. In each eye the vitreous humour was seen to be hazy, and to have numerous white flakes and films floating about in it. This condition having been previously often noticed in conjunction with secondary sy- philis, the woman was at once questioned, and as quickly admitted that she had contracted sores, and that at the present time she had a rash on her chest and shoulders. This rash proved to be syphilitic psoriasis. Here then was a case in which the stress of the syphilitic inflammation had fallen upon the vitreous, and the iris had wholly escaped. The obscurity of the vitreous prevented the state of the choroid fi'om being accurately ascertained. The patient was ordered to wean her baby, and a course of mild mercurials prescribed."* We owe to Dr. Zambaco a useful summary of the condi- tions of the fundus that may be traced by the ophthalmo- scope, in cases of insensibility of the retina, accompanying some cases of syphilis. The lesions chiefly observed are con- gestion and inflammation of the choroid, with deposits on or underneath the retina. When the exudations do not mask the retinal vessels — are, in fact, beneath the membrane — they rapidly disappear under proper treatment : hence con- siderable value attaches to the use of the instrument to note the action of remedies and the progress of relief. When the * Medical Times and Gazette, July 17, 1858. SYPHILITIC PARALYSIS 181 deposits appear on the retinal surface, tliey generally prove more obstinate. In the cases recorded by Dr. Zambaco is one of choroiditis, where the pigment had disappeared in patches, allowing the sclerotic to be seen. In another, de- tachment of the retina, and atrophy of the papilla ; and he observes, that in every case examined some appearances of lesion could be distinctly seen. Supldlitic Paralysis of the Extern d Motor {cibdmcns) Nerve. The importance of recognising this somewhat rare affec- tion in connection with syphilitic disease, has been pointed out in an excellent paper on the subject by Dr. Beyran, in the Bulletin de V Academie Imperiale de Medecine ; nor can the ad- vantages of a correct diagnosis be overrated, when we take into consideration the great value which is to be attached to prompt and early treatment. As may reasonably be inferred, the diagnosis is attended with some difficulty ; we must take into consideration the age, sex, temperament, and previous history of the patient ; the co-existence of syphilis, particularly in its secondary and ter- tiary forms, the presence of nodes, pains in the bones, and the peculiar headache, will go far to confirm our suspicions of its syphilitic origin. We may state, however, that two dis- tinct classes of phenomena characterize it: — 1. Permanent deviation inwards of the globe of the eye ; 2. A disordered condition of vision, such as double-vision, diplopia* or indis- tinctness of sight. When the adduction of the eyeball has once become established, all the efforts of the patient to restore it to its normal position are unavailing ; he can only move the eyeball either upwards or downwards towards the roof or the floor of the orbit, and that only to a very limited extent. On ex- amining the eyeball from a lateral direction, we can scarcely perceive any part of the cornea, as this membrane is almost 182 PARALYSIS OF MOTOR NERVE. entirely concealed in the inner angle of the eye ; at intervals it may show itself, but only shortly to disappear again. The pupil appears rather less dilated than that of the healthy side. With this deviation of the eyeball, there naturally arises a disordered state of vision. The patient is unable, when the sound eye is closed, to perceive clearly objects, such as the fingers, which may be placed before him, or imagines that they are twice or thrice as many as the actual number, according to the distance at which they are held. The commencement, progress, and duration of the para- lysis of the external motor nerve bear a corresponding rela- tion to the accompanying syphilitic affection, and the paralysis is modified in direct proportion to the progress of the latter, and consequently according to the effects upon it of the remedies employed. In the cases detailed by Dr. Beyran, the invasion of the paralysis was preceded by pains in the perios- teum and bones, and especially by headache, which was chiefly referred to one of the temples ; the paralysis mani- fested itself on the same side as that on which the headache was felt, and only attacked one side at a time. The treatment which is requisite is evidently that indi- cated for the elimination of the syphilitic virus. Dr. Beyran speaks highly in favour of the simultaneous administration of the biniodide of mercury and iodide of potassium, in cases in which the patient has not previously undergone any mercurial treatment ; if mercury has already been employed, the iodide of potassium alone should be ordered, and in every case this medicine should be regarded as the basis of the plan of treatment. Numerous blisters should be applied successively to the nape of the neck, and to the temple if the headache is limited to that part ; should the headache be absent, the blis- ter may be applied to the temple corresponding to the side on which the paralysis exists. For the periosteal pains, blisters, the vesicated surface to be subsequently dressed with poul- tices sprinkled with laudanum, are recommended, and when nodes are present, methodical pressure by means of sHghtly RETINITIS PIGMENTOSA. 183 stimulating plaisters sliould be resorted to. The use of electricity, iu the event of weakness of the motor muscles of the eye being present, will greatly aid in completing the cure. Retinitis Pigmentosa. A chronic form of retinal apoplexy it is usual to describe as retinitis pigmentosa, from the special character of the exu- dations in the membrane, consisting of pigmentary deposits,, sometimes appearing as black spots distributed over the retina in short radiating lines, which, when viewed by an ob- lique ray of light, may be likened to the black stripes on a tiger skin. It differs from the results of colloid degeneration of the pigmentary cells of the choroid, which presents in the ophthalmoscope appearances somewhat similar, but from which it is readily distinguished by the perfectly white spaces seen in the choroid, indicating the bloodlessness of its ause- mic condition very different from the universal sombre colour and the confused appearance of the fundus which characterize a congested retina. The changes, commencing anteriorly,, extend sloAvly towards the optic nerve entrance : where ex- udation patches, at first scarcely perceptible, ultimately form irregular dark blotches. As the disease encroaches very gradually upon the field of vision, good sight is exercised until the macula lutea becomes involved. Grafe has shown that this symptom sufiiciently enables us to distinguish it from a simi- \i\x progessive contraction of the field due to atrophy, or other cause connected with cerebral disease ; in which, hoAvever, sight diminishes in exact progression with the loss of power in the nerve. It not unfrequently happens, in cases of retinitis pigmen- tosa following retinal apoplexy, that atrophy of the mem- brane, and other organic clianges extending to the optic nerve, are a complication that quickly shows itself. This diseased condition is also often seen in connection Avith syphilitic reti- 184 RETINITIS PIGMENTOSA, nitis, when the patches are more numerous, and nearly always accompanied by myodesopia. Dr. Mooren has met with seventeen cases of this afi'ection. In all, the patients first complained of imperfect vision in bright light, and, after a while, of tension and a sense of pres- sure which almost seem to forcibly close the eyelids. Next, S}Tnptoms of hemeralopia were observed towards evening, with subjective luminous sensations in the day-time. After sunset, the patients could scarcely guide their steps amidst surrounding objects. A continual movement of the eyes was observed, but not a convulsive one as in nystagmus. Ex- amined with the ophthalmoscope, a number of blackish spots were found on the retina ; and, as the disease progressed, they became deposited at the posterior portion and over the yellow spot. The papilla of the optic nerve, already atrophied, and of a dirty-white colour, was not only more or less effaced, but often covered in part with pigment. The vessels of the retina gradually became more or less obHterated, and ap- peared as yellowish-white cords, in part concealed by pigment. The choroid became affected accordingly, and the lens lost some of its transparency, especially at its posterior portion. One of the first symptoms is a progi'essive diminution of the calibre of the vessels. This obstacle to the cu-culation not only impairs nutrition, but leads to chronic inflammatory action ; and, as a consequence, the transformation of the colouring matter of the blood into pigment, the exudation of this being a mere secondary phenomenon. The origin of these pathological conditions must be referred to material changes taking place in the vessels of the retina. The progno- sis is always unfavourable, and the treatment can only be paUiative. Retinitis Pigmentosa ; extravasation about the macula lutea. He- miopy. (Figs. 11 and 12). — Eliza A , aged 39, married; always had good health and sight until twelve years ago, when a rash, which she said looked like measles, broke out over her body ; she had also a sore throat, which was bad enough to prevent swallowing ; but does not re- WITH EXTRAVASATION. 185 member liaving hud any jiuin or redness in the eyes. She first discovered muscae in her left eye, \v!iii-h moved up and down like little specks of soot ; and found also, when reading, that the letters appeared to be on one side. A short time after, a semi-transparent blue veil, about the size of a shilling, appeared in the left eye, which partially obscured vision when she looked at anything ; but was not sufficiently dense to preclude her reading moderate-sized type. The sight of this eye has lately become worse, so that now she loses objects immediately in the axis of vision, and anything situated at the outer side she can Fia. \l.—Lpft Eye. Fig. I'l.— Right Eye. 186 RETINITIS PIGMENTOSA, barely see well enough to recognise. The right eye was healthy until the last week in Nov. ; then she felt some slight shooting pains through it, but did not discover any diminution of sight until three days ago (Dec. 19th), when she found it so dim she could not read the newspaper. Before the sight of her left eye failed, she often noticed flashes of fire upon closing her eyes. This patient, during the past twelve years, had several miscarriages, and three healthy living children. Was subject to bleeding at the nose when suckling ; during the menstrual period, the bleeding was more severe. The epistaxis has ceased about twelve months. Examined with ophthalmoscope. — Left eye, cornea, lens, and vi- treous clear ; over the entrance of the optic nerve a brownish, dull- yellow tint ; vessels distinct, though small. About the yellow spot, macula lutea, is an irregular patch, rather larger in size thdh the optic nerve, the ground of which somewhat resembles that of the optic nerve ; in several parts patches of brown and black pigment are seen ; the margin of the large patch appears of a deep brownish-red. There are also some bright-red streaks running parallel to one another at the inferior portion. The whole of the fundus of the eye has a brownish-red colour ; the ves- sels of the retina are distinctly seen, but smaller than in the healthy eye. Right eye, humours clear ; optic nerve much the same in appearance as the left ; fundus of a brownish colour, with a bluish-white floating membrane in the vitreous ; the yellow spot is covered by a fixed dark patch. The vessels of the retina are small, and not so distinct as in the left eye. The wood-cuts imperfectly represent the appearances noted. Dec. 30th, 185G. — Can now read largest print with the right eye, if looking down with the left ; on making an effort to read for a moment or two, a spot the size of a threepenny piece appears to come over the sight and partially cover up the page ; it does not, how- ever, entirely obscure the type, but renders it indistinct. Bichloride of mercury in decoction of cinchona was prescribed, which she con- tinued to take until January 16th, 1857 ; a slight diarrhoea then set in, when this medicine was changed for small doses of mercury with chalk every night, and a tonic mixture of iron and quinine twice a-day. Feb. 2nd, 1857. — Again examined with the ophthalmoscope ; the black spot not quite so large, but a large quantity of pigment still ob- scures the vessels in the left eye ; the right improving. 9th. — Examined with ophthalmoscope. — Right eye still improving ; can see better ; left optic nerve clearer, and freer from spots. Cata- WITH DETACHED RETINA. 187 menla scanty. Ordered compound iron mixture, one ounce, thrice a-day. 25th. — Improving, when she desired to leave for the country. Detached Retina, congenital retinitis pigmentosa. — Ellen P , aged 14, consulted me, Oct. 1862, for nearly total loss of sight in right eye, and considerable decrease of power and myopia in left. Can only read largest type-tests at three feet, and No. 8 at four inches. With the ophthalmoscope the right retina appears to be almost wholly de- tached, the vitreous is muddy, so that no portion of the fundus can clearly be made out ; has a slight perception of daylight from the inner or nasal side. Left eye, the chorio-capillary circulation much con- gested, as well as the vessels of the retina, which are evidently in a varicose condition. Striae of greyish-blue pigmental deposits through- out the retina, with a large black fixed deposit at the outer side of the optic disc, which is also ovid in shape. The most remarkable part of the history of this case is, that the mother of the patient is suffering from a nearly similar condition in both eyes, sight having been entirely lost in the right many years ago. The aunt and uncle, both blood relations, are likewise afflicted in the same way ; and, furthermore, the girl's maternal grandfather became rather suddenly blind some years ago, first of the right eye, then of t*he left. I therefore look upon this case as one of congenital retinitis pigmentosa, ending in total disorganization of the retina in the right eye ; and, consequently, gave an unfavourable prognosis of the left. Continental surgeons have recently directed attention to many very curious facts connected with a congenital disposi- tion to a form of retinitis pigmentosa ; the importance of which, as affecting the happiness of families, is so great, and so neces- sary to he knov^n as interesting society generally, that I feel it imperative to introduce here some remarks of Liehreich's upon the subject, accompanied with valuable statistical details of one of the many evils that are apt to result from intermarriage with near relations. When children are observed to see very imperfectly about twilight, and that the field of vision generally seems limited, it may safely be presumed that retinitis pigmentosa of the form I am speaking of is present. The disease advances with 188 CONGENITAL PREDISPOSITION age, so that about the thirtieth or fortieth year complete hlinduess ensues, previously to which fine jjrint was legible in certain parts of the field of vision where the retina still con- tinued sound. The ophthalmoscope shows extensive changes have taken place, especially in the appearances of the choroid and optic nerve entrance. Around the latter, a number of intensely black spots, frequently star- shaped, are sometimes observed. In other cases, a more decided reticulated arrange- ment spreads a thick network over the parts. Exudations also take place on the retina, which becomes more and more atrophied with increasing years. In a patient affected with this disease. Dr. Liebreich, learning that the parents were cousins, instituted an examination, among other cases of a similar nature under his care, and found that more than one half were children of relations in very close degrees of consanguinity. He extended his inquiry to discover whether retinitis pigmentosa was generally associated with the diseases well known frequently to follow, as congenital among the issue of close marriages among relations, such as cretinism, idiotism, deafness, and dumbness. M. Maffei, a French sur- geon, had previously remarked, that among cretins it was a noticeable symptom, that they did not seem to perceive small objects, although the eyes appeared perfectly healthy ; and he ascribed it to their constitutional apathy and indifference, and to not being accustomed to occupy the eye with small objects. Dr. Liebreich, however, by ophthalmoscopic examinations, has shown that this limitation of vision in cretins is due to changes in the condition of the retina. In fifty idiots he ex- amined, he found three suffering from retinitis jngmentosa ; but among these the parentage of only one could be ascertained. He was of noble descent, and his parents cousins. Marriages between near relations in this family had occurred for many generations, and its history as regards the physical condition of the offspring is both useful and instructive. The grand- father of the idiot just mentioned was married to a stranger, and had three healthy children. Of these, the eldest son was also married to a stranger, while the two daughters, one after TO RETINITIS PIGMENTOSA. 180 the other, married the same cousin. The eldest son has had eleven healthy children, of whom nine are alive, and part of them married, and have also begotten healthy children. Only one of these married a cousin, and ho has one idiotic child and six healthy ones. Of the two daughters just mentioned, the elder, who married her cousin, died while giving birth to her first child, which was still-born. Her husband then married the deceased wife's sister, and had by her thirteen children. Of these, two died in the first year ; the third died somewhat later, from dysentery; a fourth, who was completely paralysed, lived to the age of sixteen ; a fifth and sixth are quite blind : and, according to the description given, most probably in consequence of retinitis pigmentosa. The seventh, whom Dr. Liebreich has examined, is idiotic and affected with retinitis pigmentosa. The other six children were healthy ; one of them is married to a stranger, and has no children ; another is married to a cousin, and has one idot child among seven. A third, who married a cousin, has only one feeble child ; the other three healthy ones are unmarried. Of 34 deaf and dumb persons in Berhn, examined by Dr. Liebreich, fourteen were affected with retinitis pigmentosa; and among these there were no less than eight Jews, whose affiiction may be ascribed to the frequency, of marriages of consanguinity. Among them was a family of five children, sisters and brothers, whose history is also remarkable. The father is a healthy soldier, but given to hard drinking. He married the elder of two sisters, by whom he had six children, three of which were deaf and dumb. By a subsequent mar- riage with the younger sister of his wife he had a son, who was also deaf and dumb. All the children suffered from re- tinitis pigmentosa ; and Dr. Liebreich has always found that, if deafness and dumbness and retinis pigmentosa are prevalent in a family, the children who suffer from one are also affected with the other ; and that those who are free from the one, are free from the other. Of 35 other cases of retinitis pigmmtosa examined by Dr. Liebreich, fourteen were the offspring of marriages of consanguinity. Grafe has since observed, in 190 DETACHED RETINA, eleven cases out of twenty-five of retinitis pigmentosa under his care, that the circumstances were such as confirmed the statements of Dr. Liebreich. Detached Retina. The retina is subject not only to the ordinaiy hazy obscuration, the result of inflammatory action, but also to a more permanent condition of disease, due to extravasa- tion. This, when followed by traumatic injury, though more distinctly marked, is not more serious than when con- sequent upon continued inflammatory action. In its first stage, as has been pointed out by Dr. Jager in chronic reti- nitis, " the fundus of the eye seems to reflect less light than usual. To a practised eye it resembles some^.vhat those cases in which the vitreous humour from some cause has lost a little of its transparency, with this distinctive difl"erence, that in the latter cases the cloudiness is uniform throughout the medium, whereas in retinitis it is confined to the vicinity of the optic nerve. The cause of this phenomenon is probably that the colour of the fundus of the eye is changed. Instead of being, as in health, of an orange-red, it has assumed a blood- red hue, especially around the optic disc, and that this more sombre colour reflects less light." Patients in this stage complain of a hazy dimness in their sight. Any sudden con- cussion of the body, such as is occasioned by stumbling, coughing, or sneezing, produces flashes of broken light, as if a blow had been received on the eye. Sometimes vision is constantly interfered with by brightly-coloured spectra in the forms of rings or spots. As the disease advances, the margin of the optic disc is seen to be encroached upon by a fasciculus of vessels starting from a central point, and the circumference extending to in- clude the retina ; but with such an indefinite gradation of effect, that it is difiicult to determine where the yet unaf- fected portion meets the congested membrane. The papilla OPHTHALMOSCOPIC APPEARANCES OF. 191 is early involved, and in advanced or confirmed cases is en- tirely covered, so as to require considerable care in making it out. The central arteries and veins being larger than in health, enable the observer to mark the situation of the optic disc. In the worst cases of all, however, the large central vessels even disappear in the general sombre hue of the fun- dus, upon which short radiating lines of a deeper tint may be discerned, where the texture of the retina appears of a firmer consistence. These alterations on the aspect of the retina are accompa- nied by corresponding changes in the condition of the choroid, and consequent extravasation between these membranes. "When the retina becomes quite detached by the effusion, it projects towards the lens. The periphery of the optic nerve apparently limits the further extension of the effusion at that point, and the infiltrated or detached part becomes raised around and hangs over it. The raised portion has a more or less opaque and pinkish appearance, and sometimes admits of the choroid being seen through it. Grafe directed particular attention to the detachment of the retina from the choroid by extravasation or exudation ; as well as by exudation of plastic lymph, the production of tubercular disease, and by malignant growths. Bonders has carefully investigated and represented colloid degeneration of the pigmentary cells of the choroid. Congestion of the choroid (choroiditis), and sclero-choroiditis, so frequently met with, always exhibit a peculiar train of subjective symp- toms ; so that we may, by the more careful examinations we are now enabled to make with the ophthalmoscope, readily recognise such organic changes from those before mentioned.* * In retinitis and choroiditis, the appearances, as hitherto observed with the ophthalmoscope, are more frequently those of past inflammation, than of an active state ; they are congestions, spots of extravasated blood, opacities of various degrees, and pigmental deposits. Some of the opaque appearances are indications of exuded matter deposited between the choroid and retina, producing adhesion of the two membranes, with alteration of their textures, including the pigment membrane of the one and stratum bacillosum of the 192 DETACHED RETINA. Detached Retina, from exudation. — Griife, who frequently observed cholesterine in the lens, or suspended in the anterior chamber, adhering to opacities in the vitreous humour, or glistening on the surface of the detached retina ; has also observed it where exudation separated the retina from the choroid. The following case is interesting, as one of complete detachment of retina : — " In a delicate girl, ten years of age, blind nearly from birth with the right eye, tlie eyeball being abnormal. The pupil gave no re- action when light was thrown into the eye, but moved on rotation of the eyeball, and sympathetically with the pupil of the left eye. At a cer- tain distance, and under favourable illumination, particularly if the pupil was dilated by closing the left eye, the white reflection from the background, characteristic of retinoid detachment, was apparent. After dilating the pupil, this could be made out without the ophthalmoscope, and even the arborescent retinal vessels could be distinguished. " The ophthalmoscope showed the lens and vitreous humour to be quite transparent, and a nearly total detachment of the retina, present- ing the usual funnel- shape, converging towards the optic papilla, which, was still plainly visible. The walls of the funnel were formed by ele- vations of retina, separated by furrows and projecting in different heights into the vitreous humour. At first Grafe was struck by a number of white, glistening, club-shaped, cylindrical bodies, the ap- pearance of which justified him in coming to the conclusion that they were cholesterine crystals, but not, as in similar cases, adherent to the anterior surface of the detached retina, but partly situated on its pos- terior surface, and partly floating about in the fluid effused between retina and choroid." Detached Retina. — A porter, aged 40, suffered from hemiopia of the right eye, which for about a year remained stationary, when a gradual diminution of sight came on. The patient saw objects only from the inner and upper portion of the retina, and then but faintly. The eye presented a slight divergence from the optic axis. Pupils other; and this has been frequently confirmed by dissection. The retina bulged forward and tremulous is an indication of serous exudation between the choroid and it on the one hand, and dissolution of vitreous humour on the other.— Wharton Jones's ' Ophthalmic Medicine and Surgery.' RETINAL EXUDATION. 193 sluggish. The ophthahnoscope showed a separation in the retina towards the lower and outer portion, stretching somewhat over to the inner side. It had the appearance of a greyish-white folded mem- brane ; and with every motion of the eye it waved too and fro. The veins appeared very dark and thick, taking a serpentine course towards and over the retina. The arteries were apparently split up into numerous fine branches, deeply colouring the retina, and the ojitic nerve had a bluish centre. Retinal exudation, with Myodesopia. — November, 1853, Filliond, a cook, aged 29, presented himself at the hospital, complaining of imperfect vision in the right eye. " On examination, the eye appeared normal ; no injection in the conjunctiva, nor in the sub-conjunctival tissue. The colouration of the iris natural ; the pupil free, transparent, and dilated. Six months ago, this man received a contusion by running against a wall. It was only four months afterwards, when, by chance, in closing his left eye, he perceived that he was nearly deprived of sight in the right, and from that time he saw a large cobweb before his eye. " Examined with ophthalmoscope. — In the posterior segment of the vitreous there are three large brown flaky bodies, connected together by several fine filaments, forming a sort of lace, spread athwart in the ocular cavity, and situated rather close to the retina, intercepting the luminous rays and preventing the formation of images. During move- ments of the eye, the mass moves from below upwards, and again sinks to the bottom of the organ. What is most striking in these movements is that they are confined mostly to the fundus of the eye ; the disease no doubt affects only the posterior segment of the vitreous body."* Retinal Effusion, and (Edema of Retina. Partial effusion beneath the retina may be recognized by the characteristic pale bluish tint of the affected por- tion, whilst the rest of the fundus exhibits its usual normal aspect. In a case of this kind, if the eye is tiu'ned in one direction, the optic papiUa exposed will appear * Dr. Anagnostakis, 'Essai sur I'exploration de la Rotine." 194 RETINAL EFFUSION, whitish, if this be occupied by the detached portion of the retina ; whilst, turned in the other direction, the fundus be- comes rose-coloured as the sound part is offered for ob- servation. Another prominent feature is the very palpable line of demarcation between the healthy and unhealthy por- tions, formed by the passage of the vessels over these contrasted conditions of the membrane, being sometimes transverse and more or less oblique, and at other times un- dulatory and even convex. Partial effusion may be complicated with chemosis and synchysis. The causes of sub-retinal effusion are involved in much obscurity. M. Grafe, who considered it generally the conse- quence of haemorrhage from the choroid, based his opinion upon cases in which patients suddenly observed an appear- ance as of red blood interfering with vision, becoming in a few days yellow, and then as suddenly losing all sense of colour. The same observer remarks, that effusion frequently accom- panies penetrating wounds of the sclerotic in parts distant from the cornea. It has been found to follow the sudden application of cold to the eye ; and, in cases of erysipelas of the face, such symptoms appearing have been considered to indicate a like complication. Kemiopia is the principal sign of partial effusion of the retina. A kind of misty veil or screen obstructs the upper portion of the visual field, which gradually increases in in- tensity until finally it becomes quite black. It must always be considered a very serious affection ; but it sometimes affords instances of successful practice where correct diagno- sis in the first instance has led to proper care and treatment. Absorption of the contained fluid is the object to be obtained, and which of course suggests, according to character of con- stitution or the history of the case, whether a purely tonic or counter-irritant course of practice is to be followed. Plastic Exudations on the Retina are distinguished from the white spots of the atrophied choroid by their shape, which is generally elongated and narrow, forming irregular bands, or, sometimes, fine white lines along the course of the vessels : , WITH HEMIOPIA. 105 by their colour, which has a greenish or bluish shade, instead of tlie silvery white of the choroidal spots ; by the disposition of such of the retinal vessels as may pass their situation ; these cross, unchanged, the choroidal spots, but are covered and concealed by the exuded matter. Where the deposit is recent, it forms a fine bluish glaze over the surface of the retina. Retinal Effusion ; Hemiopia. — "Mme. Gondalier, a needle-woman, aged 26, had enjoyed excellent health till the month of February, 1863, when, after working during a great part of the night, she rose in the morning with considerable dimness in her eye- sight. This state grew worse fi-om day to day, and, since the month of October, with the left eye, which is the one most affected, can hardly see large objects ; and of these she only distinguishes the lower part, the upper part escapes her. " The sub-conjunctival tissue is hijected, the pupil dilated, but per- fectly translucent ; the iris retains its natural aspect ; the patient has never experienced myopia. " Examined with ophthalmoscope. — The vitreous humour is full of brown flakes, floating during every movement of the eye. At the in- ferior part of the ocular cavity is seen a greenish mass, in appearance rather solid. It is free, and always sinks down to the bottom of the eye. In all probability this is an old hsemorrhagic exudation into the vitreous. The retina is not altered ; the (half-vision) hemiopia, of which the patient complains, seems to be owing to the obstacle which the opaque masses oppose to the rays of light as they pass to the retina." Insensibility of Retina from effusion — (Fig. 18). — S. E , aged 27, schoolmaster. Gradual dimness of sight came on in both eyes, so much so, that since May last he has been obliged to resort to strong magnifying glasses, which have barely enabled him to continue his duties. Being a nervous man, he suffers much from a di-ead of loss of sight ; is frequently troubled with headache and constipation of bowels ; candle-light distresses him much ; he is compelled in conse- quence to discontinue reading at night. Pupils dilated — mydi-iasis ; with this exception, there is nothing to indicate the existence of disease. With ophthalmoscope, the dioptric media appear to be perfectly clear ; fundus of eyes alternately pale and red in colour, with a few irregular white patches. A pale bluish cloud suspended as it were before the 2 196 RETIXAL EFFUSION. optic nerve, and partially obscures the retina ; the periphery of optic nerve, at upper two-thirds, presents an irregular raised aj)pearance. To take two of the Pil. Hydrarg. cum Galb. every night. Fig. \Z.— Left Eye. . July 1 2th — Improving ; bowels sluggish. Continue pills, and, in addition, sulphate of magnesia, one ounce, dilute sulphuric acid, t\vo drachms, infusion of calumba, twelve ounces, one ounce three times a day. On the 30th this patient was discharged, improved, and able to go to the country ; he has since had no return of the affection. Retinitis, with effusion. — W. S , aged 16, a spare -looking lad, Came to me February 18th, 1857, complaining of imperfect vision in left eye, which obliged him to give up school ; when reading only for a few minutes, one line runs into another, especially if anxious to read ; his head " feels as if something floated about in it ; " pain and occasional loss of power over the left arm and side, with loss of appetite ; the only apparent change in the eyes was a slightly dilated state of the pupils, with consideraljle tension, and a peculiar greenish-looking vitreous. Examined with ophthalmoscope. — Vessels of retina large, congested, and irregular, veins particularly so. A few vessels running horizon- tally from the papilla over the foramen centrale. Hsemorrhagic patches, with a pigmental deposit near superior and inner periphery of optic nerve ; fundus of the eye of a brick-dust red colour. The retina appears of a bluish grey colour, and is pushed out apparently by effusion between it and the choroid. Lenses quite clear. The pain in head. (EDEMA OF RETINA. 197 with other symptoms of cerebral irritation, induced me to prescribe mercury, cluilk, and rhubarb powders, niglit and morning. On the 25th, the boy was much better ; at the end of March, had improved so much that he could read steadily for some time without fatigue. (Edema of the Retina indicates as much disturbance in the circulation of the membrane, as does serous chemosis in that of the conjunctiva. The fundus of the eye is pale, and the retina appears as if raised in the form of a wall around the optic papilla. A yellowish tinge of colour in the retina renders it less brilliant than in the healthy state. It is easily distinguished, after a few observations, from turbidity of the vitreous humour, with which it is liable to be confounded. " E. W , agt d 19, resident in a low, marshy part of the country, had suffered many months from amennorrhcea, with anaemia, intercostal neuralgia, palpitation, &c. She was then attacked with intermittent su])ra- orbital neuralgia ; and shortly after, the sight of the right eye suddenly failed, " every lining being concealed as if by snow." She had not seen any muscte, nor any flashes, of light. There was no external appearance of disease. With the ophthalmoscope, the fundus of the eye was found to be unusually pale, and the retina appeared as if infiltrated with fluid : in fact, it very much resembled serous chemosis as it occurs in the conjunctiva. At the first glance, I confess to have mis- taken it for turbidity of the vitreous humour; but more attentive observation, and the fact that the retinal vessels were clearl}"- visible, demonstrated the true nature of the case. The (Edema was greatest round the optic disc. It appeared to be connected with congestion of the choroid. She completely recovered in about six weeks."* James G , aged 19, mariner, applied January 16th. Complained of his sight being defective when a boy, and in consequence recommended to take to a sea-faring life. The last 12 months, been getting worse, dark specs and a web continually before his eyes ; can only make out large objects, cannot even read large print ; general health good ; a drop of atropine applied to the eyes, two days befoi'e he came to me, very * M. Desmarrcs' ' Traits dea Maladies dcs Ycux.' 198 (EDEMA OF RETINA. much increased the confusion of vision, particularly in right eye. A dull light suits him best. Examined with ophthalmoscope. — Dioptric apparatus clear ; optic nerve somewhat exposed, with a pinkish-grey inner ring raised and surrounding optic papilla, pigment exposed, retinal vessels very irregular. The fundus generally has a raised, mottled appearance (Fig. 14). A few patches darker in colour than the rest ; no spots or specs to be seen, either floating or fixed, in the vitreous. The uncoloured wood- cut very imperfectly represents the appearance of the fundus. Fig. li.— Right Eye. He could not be persuaded to give up his employment, or take rest. A tonic plan of treatment was ordered ; the usual mixture of iodide of iron with quinine was continued for a month. Feb. 19th. — Much improved; wished to have his medicine con- tinued ; and when last seen, said he scarcely felt any inconvenience from an imperfection once so troublesome to him. John M , aged 23, a discharged soldier, applied February 4th. Served several years in India during the war, and, on his return, entered the Land Transport Corps for the Crimea ; while there, hard worked, and constantly employed in writing and keeping the journal ; smoked a great deal, but never lived fast. When he returned to this country, the corps was disbanded, and he v;as discharged. His sight, which during the latter part of his service was growing dim, became NIGHT BLINDNESS. 19*^ very imperfect, iind he can now scarcely see the largest print on the hospital letter. Had suffered a good deal from swelling of the legs. Examined with ophtlialnwscope. — A grey ring occu[)ies the central part of the optic nerve in tlie right eye, the peripheral margin of which is very irregular. Retinal vessels small ; retina appears displaced, and oedematous {Fig. 15). The man is very pallid and nervous, and much dejected about his present impoverished condition ; he is also badly clothed and ill fed. Under a tonic plan of treatment, he began to improve ; country employment at this time was offered to him, which he accepted, and left the hospital. Fig. 15. — Ri(/Jit Eijp. Hemerah'pia and Nydalojna. Night Blindness. — There is a peculiar affection of the retina which renders the eye insensible, except to a strong degree of light. It frequently occurs suddenly, and as it first betrays itself on the approach of darkness, it has been called night- blindness. With the light of day, sight gradually returns ; and, again, at sunset, the patient perceives symi)toms of a returning failure of vision. Exposure to an unusual glare of 200 MIGHT BLINDNESS light has been known to induce night-blindness, even in this countiy. This disease appears frequently in tropical climates. Mr. Banifield has recorded in the Medico-chirurgical Transactions more than a hundred cases of idiopathic and two hundred of symptomatic night-blindness, which had occurred in his practice in different parts of the globe, but chiefly in the East Indies, all of which recovered. Hence he infers that, under proper treatment, the prognosis may be generally favourable. De Servieres records a case in which fixedly looking at the rising sun produced an attack. Other cases on record are said to have been owing to spermatorrhoea, and similar debilitating causes. In most of them there appears to be scarcely anything remarkable in the appearances of the eyes from those in health. The pupils are sometimes dilated, and do not contract on exposure to a moderate light : whilst in others they are contracted, and exhibit a painful irritabihty on exposure to a strong light ; even the reflection from the sea will produce pain. Hemeralopia — night-blindness — seems to have been more generally prevalent than that of day-bUudness during the Crimean war, as appears by a Report made to the Direc- tor General. Bad food, exposure, with scurvy, were the pre- cursors of the attack in nearly all the men so affected. Hemeralopia, Night Blindness in the Crimea. —" Vr'wolQ John Grady, of the 9th Regiment, was admitted into the Regimental Camp Hospital before daylight on the morning of the 13th February, 1855. " He stated that he formed one of the advance on the WoronzofFroad the previous night, and that he and a comrade were directed to keep a sharp look-out, which they agreed to do by turns ; that, about half-past three, he fell asleep for a few minutes, and on awaking was surprised to find that he had totally lost his sight. " He was immediately taken up to camp, where he was attended to ; he stated that he had no pain or ailment with the exception of the total, and to him unaccountable, loss of sight. When a candle was brought IN THE CRIMEA. 201 into the tent, some vision returned ; but he could not see the flame dis- tinctly, and said it seemed as if" surrounded by motes. The pupils were very much dilated, more particularly the right ; both acted freely. No abnormal vascularity of any of the textures of the eye w^as visible. The entire cornea seemed prominent ; but this w^as said to be their normal state. " As the daylight returned, he recovered his sight ; but all through tlie day he complained of a sort of haze and a dimness, with constant symptoms of musctB volitantes. " The nights at the same time were very dark, and there was about four inches of snow on the ground. " There were no remarkable symptoms preceding his attack, which came on regularly as night approached. On very bright moonlight nights, he could see a little ; but could not discern any small or dark object, and the looking at them caused him severe pain in the eyes for rather more than six weeks. It then began gradually to wear off ; but he had occasional relapses, both on dark nights and when exposed to a very bright light. He was always near-sighted, and this did not seem to be increased by the attack. " This man, in common with his comrades, was and had been for three months enduring the greatest privations, exposed to constant night-work in the trenches ; his clothes were scarcely ever dry, and his food consisted for the most part of salt meat and biscuit. He had been suffering from that diarrhoea which in the Crimea was considered scorbutic, as it was neither true dlarrhcea nor dysentery, but a state of the Ijowels which was induced by the bad living. " The treatment consisted in the administration of quinine and ipeca- cuanha to try and promote the action of the skin ; blisters to the temples, with belladonna round the eye ; but good living with fresh meat and vegetables being soon afterwards procurable, these seemed to benefit the patient more than anything else."* Ilemeralopia : Retinitis Pigmentosa. — Eliza W , aged 30, a glove-maker, applied Nov. 19th, 1862, stating that about five years ago she discovered her inability to go about at night, and which for the last three years has been so very troublesome, that if she attempts to walk out after sunset, a " kind of shade comes over her eyes, and she runs against everybody." This affection has been on the increase Mr. J. C. Ovens. ' Op. H. R.' July, 1859. 202 DAY BLINDNESS. since her last confinement, now five months since (her infant only surviving its birth three months) ; a leucorrhoeal discharge has also troubled her up to the present time. The ophthalmoscope disclosed, in right eye particularly, retinitis pigmentosa, with a saucer-like cupping of the optic ners^e ; this is not so well seen in the left ; in both, the retinal vessels are congested. Reads with some difficulty, the letters running into each other. Looking upon the disease as one of debility, I ordered her to take the Pil. Hyd. cum Ferro. every night, with the iron and quinine mixture three times a-day ; to use an astringent injection night and morning. Under this treatment her sight and health very much improved, and she was able to resume her occupation at the end of January, 1863. Nyctalopia, Day Blindness ; Retinitis Pigmentosa ; from exposure and scurvy. — T. J , aged 46, a sailor in the Queen's service, was sent home from Constantinople. He stated that his health had been always good, except on one occasion when he suffered fi'om syphilitic disease seventeen years ago. In the month of March, while in the Crimea, after having lived entirely on salt provisions without vegetables, he had symptoms of scurvy. At the same time was exposed to the cold ^\'inds and hail, and, during three weeks' work in snow, he was attacked with a bleeding at the nose which lasted five hours, which ceased when he was made warm and comfortable. Four days after this, his eyes were much inflamed and ran with water ; this attack lasted about three weeks, during which time he found he could only see about night-fall ; he was unable to find his way about, and was sent to hospital, where he was cupped, blistered, and bled from the arm until he felt much weakened, his sight not being in the least improved ; he was then sent to the hos- pital at Constantinople, and a tonic plan of treatment prescribed After a short lapse of time, he was able to resume his work by night, but not at all during the day. He tried several kinds of spectacles ^vithout benefit. 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Being a Digest of the Contents of the principal British and Continental Medical Works; together with a Critical Report of the Pro- gress of Medicine and the Collateral Sciences. Post 8vo. cloth, 6s. 6d. Vols. I. to XLII. THE PHARMACEUTICAL JOURNAL, Containing the Transactions of the Phae- macedtical societt. Published Monthly, price One Shilling. *** Vols. I. to XXIV., bound in cloth, price 12s. 6d. each. THE BRITISH JOURNAL OF DENTAL SCIENCE. Published Monthly, price One Shilling. Nos. L to CXIV. THE MEDICAL DIRECTORY FOR THE UNITED KINGDOM. Published Annually. 8vo. cloth, 10s. 6d. ANNALS OF MILITARY AND NAVAL SURGERY AND TROPICAL MEDICINE AND HYGIENE, Embracing the experience of the Medical Offi- cers of Her Majesty's Annies and Fleets in all parts of the World. Vol. I., price 7s. '^^i^^- -3^- tm^^*^' A CLASSIFIED INDEX MISS1.S. CIMOOLi k mW CAIALiWI. ANATOMY. Pack Anatomical Remembrancer . . 3 Flower on Nerves 11 Hassall's Micros. Anatomy .. 14 Heale's Anatomj' of tlic Lungs 14 Heatli's Practical Anatomy .. 10 Holden's Human Osteology .. 15 Do. on Dissections .. ..15 Huxley's Comparative Anatomy 1 G Jones' and Sieveliing's Patlio- logical Anatomy 17 Jlaciise's Surgical ^Vnatomy . . 19 St. Bartliolomew's Hospital Catalogue 24 Sibson's Medical Anatomy . . 25 Waters' Anatomy of Lung . . 29 Wlieeler's Anatomy for Ai-tists 30 Wilsou's Anatomy 31 CHEMISTRY. Abel & Bloxam's Handbook . . 3 Bernays' Notes for Students . . (i Bo^nuan's Practical Cliemistry 7 Do. Medical do. . . 7 Fownes' Manual of Cliemistry . . 12 Do. Actonian Prize .. .. 12 Do. Qualitative Analysis . . 12 Fresenius' Chemical Analysis . . 12 Galloway's First Step . . . . 12 Do. Second Step .. ..12 Do. Analysis 12 Do. Tables 12 Griffiths' Four Seasons .. ..13 Horsley's Chem. Philosophy .. 10 Mulder on the Chemistry of Wine 20 Plattner& JIuspratton Blowpipe 22 Speer's Pathol. Chemistry . . 26 Sutton's Volumetric Analysis . 27 CLIMATE. Aspinall on San Remo . . . . 4 Bennet's Winter in the Soutli of Kurope 6 Chambers on Italy 8 Dairy mple on Egypt 10 Francis on Cliange of Climate . . 12 Hall on Torquay 14 Ha\'iland on Climate 14 Lee on Climate 18 Do. Watering Places of England 1 8 McClelland on Bengal .. ..19 McNicoU on Southport . . . . 19 Martin on Tropical Climates . . 20 Moore's Diseases of India . . 20 Scoresby-Jackson's Climatology 24 Shapter on South Devon . . . . 25 Siordet on Mentono 25 Taylor on I'au anJ Pyrenees . . 27 DEFORMITIES, &c. Adams on Spinal Curvature . . 3 Bigg's Orthopraxy Bishop on Deformities . . . . H Do. Articulate Sounds . . 6 Brodhurst on Spine 7 Do. on Clubfoot . . . . 7 Godfrey on Spine 13 Hugman on Hip Joint .. .. Ifi Tamplin on Spine 27 DISEASES OF WOMEN AND CHILDREN, paok Ballard on Infants and Mothers 4 Bennct on Uterus 6 Do. on Uterine Pathology.. G Bird on Children G Bryant's Surg. Diseasesof Child. 7 Eyre's Practical Remarks . . U Harrison on Children .. ..14 Hood on Scarlet Fever, <&c. . . 16 Kiwisch (ed. by Clay) on Ovaries 9 Lee's Ovarian &, Uterine Diseases 18 Do. on Specuhim 18 Ritchie on Ovaries 23 SeJ^uour on Ovaria 25 Smith on Leucorrhoea . . . . 26 Tilt on Uterine Inflammation . . 28 Do. Uterine Therapeutics . . 28 Do. on Change of Life . . . . 28 Underwood on Children . . . . 29 Wells on the Ovaries 30 West on Women 30 Do. (Uvedale) on Puerperal Diseases 30 GENERATIVE ORGANS, Diseases of, and SYPHILIS. Acton on Reproductive Organs 3 Coote on Syphilis 10 Gant on Bladder 13 Hutchinson on Inlierited Syphilis 16 Jiidd on Syphilis 17 Lee on Syphilis 18 Parker on SjTJhilis 21 Wilson on Syphilis 31 HYGIENE. Araistrong on Naval Hygiene 4 Beale's Laws of Health . . . . 5 Do. Health and Disease . . 6 Bennet on Nutrition 6 Carter on Training 8 Chavasse'sAdviceto aMother.. 9 Do. Advice to a Wife . . 9 DobeU's Germs and Vestiges of Disease 11 Do. Diet and Regimen . . 11 Fife & Urquhart on Turkish Bath 1 1 Granville on Vichy 13 Hartwig on Sea Bathing .. ..14 Do. Physical Education 14 Hufoland's Art of prolonging Life IG Lee's Baths of Germany .. ..18 Do. do. Switzerland .. 18 Moore's Health iu Tropics . . 20 Parkes on Hygiene 21 Parkin on Disease 21 Pickford on Hygiene .. ..21 Robertson on Diet 24 Routh on Infant Feeding.. .. 23 Tunstall's Bath Waters . . . . 28 Wells' Seamen's Medicine Chest 30 Wife's Doiiiain 30 Wilson on Healthy Skin .. ..31 Do. on Jlineral Waters .. 31 Do. on Turkish Bath .. ..31 MATERIA MEDICA and PHARMACY. Bateman's Magnacopia . . . . ■'' Beasley's Formulary . . .. .. 5 Do. Receipt Book .. .. 5 Do. Book of Prescriptions 5 Frazer's Materia Jledica . . .. 12 I Nevins' Analysis of Pharmacop. 20 MATERIA MEDICA and TKASMACY— continued. Pereira's Selecta fc Prajscriptis 21 Pharmacopreia Londinensis .. 22 Proscriber's Phaniiacoposia . . 22 Royle's Materia Medica . . . . 24 Squire's Hospital Pharraacopaiias 26 Do. Companion to the Phar- macopseia 26 SteggaU's First Lines for Che- mists and Druggists . . . . 26 Stowe's Toxicological Chart . . 27 Taylor on Poisons 27 Waring'3 Therapeutics . . . . 29 Wittstein's Pharmacy . . . . 31 MEDICINE. Adams on Rheumatic Gout . . 3 Addison on C ell Therapeutics . . 3 Do. on Healthy and Dis- eased Stnicture 3 Aldis's Hospital Practice . . . . 3 Anderson (iVndrew) on Fever . . 4 Do. (Thos.) on Yellow Fever 4 Austin on Paralysis 4 Barclay on Medical Diagnosis . . 4 Barlow's Practice of Medicine 4 Basham on Dropsy 5 Brinton on Stomach 7 Do. on Ulcer of do 7 Budd on the Liver 8 Do. on Stomach 8 Camplin on Diabetes 8 Chambers on Digestion . . . . 8 Do. Lectures 8 Cockle on Cancer 9 Davey "s Ganglionic Nervous Syst. 1 1 Eyre on Stomach H French on Cholera 12 Fuller on Rheumatism .. ..12 Gairdner on Gout 12 Gibbon Throat 13 Granville on Sudden Death .. 13 Gully's Simple Treatment .. 13 Habershon on the Abdomen . . 13 Do. on Mercury .. ..13 Hall (Marshall) on Apncea .. 14 Do. Observations .. 14 Headland — Action of Medicines 14 Hooper's Physician's Vade- Mecimi 13 Inman's New Theory .. ..16 Do. Myalgia 16 James on Laryngoscope .. ..17 Maclachlan on Advanced Life. . 19 Jlarcct on Chronic Alcohohsm . 1 9 Meryon on PanJysis . . . . 20 Pav)' on Diabetes 21 Peet's Principles and Practice of Medicine 21 Richardson's Asclepiad .. ..23 Roberts on Palsy 23 Robertson on Gout 24 Savory's Compendium . . . . 24 Scmiile on Cough 24 Seymour on Dropsy 25 Shaw's Remembrancer . . . . 25 Smee on DcbUity 25 Thoma.s' Tractice of Physic . . 27 Thudiclium on Gall Stones .. 28 Todd's Clinical Lectures .. .. 28 Tweedic cm Continued Fevers 29 Walker on niphtheria What to Observe at the Beds Williams' Principles . Wright on Headaches —©4 ■y&-^ CLASSIFIED INDEX. MICROSCOPE. Beale on Microscope in Medicine 5 Carpenter on Microscope . . . . 8 Schacht on do 24 MISCELLAlfEOTTS. Acton on Prostitution . . . . 3 Barclay's Medical Errors . . . . 4 Barker & Edwards' Photographs 4 Bascome on Epidemics . . . . 4 Blaine's Veterinary Art . . . . 7 Bourguignon on the Cattle Plague 7 Bryce on Sebastopol 7 Buckle's Hospital Statistics . . 8 Cooley's Cyclopaadia 9 Gordon on China 13 Graves' Physiology and Medicine 1 3 Guy's Hospital Reports . . . . 13 Harrison on Lead in Water . . 14 Hingeston's Topics of the Day . . 15 Howe on Epidemics 16 Lane's Hydropathy 18 Lee on Homceop. and Hydrop. 18 London Hospital Reports . . . . 19 Marcet on Food 19 Massj' on Recruits 20 Mayne's Medical Vocabulary . . 20 Part's Case Book 21 Redwood's Supplement to Phar- macopoeia 23 Ryan on Infanticide 24 Snow on Chloroform 26 St«ggall's Medical Manual . . 26 Do. Gregory's Conspectus 26 Do. Celsus 26 Whitehead on Transmission . . 30 NEEVOUS DISOEDEES AND INDIGESTION. Birch on Constipation . . '. . 6 Carter on Hysteria 8 Downing on Xeuralgia . . ..11 Hunt on Heartburn 16 Jones (Handfield) on Ftmctional Nervous Disorders 17 Leared on Imperfect Digestion 18 Lobb on Xervous Affections .. 19 Radcliffe on EpUepsy . . , . 22 Reynolds on the Brain . . . . 23 Do. on Epilepsy . . . . 23 Rowe on Kervous Diseases . . 24 Sieveking on Epilepsy . . . . 25 Tumbtill on Stomach . . . . 28 OBSTETEICS. Barnes on Placenta Praevia . . 4 Hodges on PuerperalConvnlsions 15 Lee's Clinical Jlid^rifery .. ..18 Do. Consultations 18 Leishman's Mechanism of Par- turition 18 Mackenzie on Phlegmasia Dolens 19 Prett}''3 Aids during Labour . . 22 Priestley on Gravid Uterus . . 22 Ramsbotham's Obstetrics . . . . 23 Do. Midmfery . . . . 23 Sinclair & Johnston's Jlidwifery 25 Smellie's Obstetric Plates . . . . 25 Smith's Manual of Obstetrics . . 26 SwajTie's Aphorisms 27 Waller's Midwifery 29 OPHTHALMOLOGY. Cooper on Injuries of Eye . . 9 Do. on Xear Sight . . . . 9 Dalrymple on Eye 10 Dixon on the Eye 11 Hogg on Ophthalmoscope . . 15 Hulke on the Ophthalmoscope 16 Jacob on Eye-baU 16 ©^ — OPHTHALMOLOGY-cont''- ekOK Jago on Entoptics 17 Jones' Ophthalmic Medicine . . 17 Do. Defects of Sight . ..17 Do. Eye and Ear 17 Nnnneley on the Organs of Vision 2 1 Solomon on Glaucoma . . . . 26 Walton on the Ej-e 29 WeUs on Spectacles 30 PHYSIOLOGY. Carpenter's Human 8 Do. Comparative . . . . 8 Do. Manual 8 Heale on Vital Causes .. ..14 O'ReUly on the Nervous System 21 Richardson on Coagulation . . 23 Shea's Animal Physiology 25 Virchow's (ed. by Chance) Cel- lular Pathology 8 PSYCHOLOGY. Arlidge on the State of Lnnacy 4 BucknUl and Tiike's Psycholo- gical Medicine 8 ConoUy on Asylums 9 Davey on Nature of Insanity . . 11 Dunn's Physiological Psychology 1 1 Hood on Criminal Lunatics . . 15 MUlingen onTreatmentof Insane20 Noble on Mind 21 Williams (J. H.) Unsoundness of Mind 30 PULMONARY and CHEST DISEASES, &c. Alison onTulmonary Consump- tion ..' 3 BUling on Lungs and Heart . . 6 Bright on the Chest 7 Cotton on Consumption .. ..10 Do. on Stethoscope .. ..10 Davies on Lungs and Heart .. 10 Dobell on the Chest 11 Fenviick on Consumption . . ..11 FnUer on Chest 12 Do. on Heart 12 Jones (Jas.) on Consumption.. 17 Laennec on Auscultation . . . . 18 Markbam on Heart 20 Peacock on the Heart .. ..21 Richardson on Consumption . . 23 Salter on Asthma 24 Skoda on Auscultation . . . . 20 Thompson on Consumption . . 27 Timms on Consumption . . . . 28 Tumbull on Consumption . . 28 Waters on Emphysema . . . . 29 Weber on Auscultation . . . . 29 EENAL and UEINARY DISEASES. Acton on Urinary Organs . . 3 Beale on Urine 5 Bird's Urinary Deposits . . . . 6 Coulson on Bladder 10 Hassall on Urine 14 Parkes on Urine 21 Thudiclmm on Urine . . . . 28 Todd on Urinary Organs . . . . 28 SCIENCE. Baxter on Organic Polarity . . 5 Bentley's Manual of Botany . . 6 Bird's Natural Philosophy . . 6 Craig on Electric TenMon .. 10 Hardwich's Photography .. .. 14 Hinds' Harmonies 15 Howard on the Clouds . . . . 16 SCIENCE — cotdinued. riom Jones on Vision 17 Do. on Body, Sense, and Mind 17 Maj-ne's Lexicon 20 Pratt's Genealogy of Creation . . 22 Do. Eccentric & Centric Force 22 Do. on Orbital Motion . . . . 22 Do.Astronomicallnvestigations 22 Do. Oracles of God 22 Price's Photographic Manipula- tion 22 Rainey on Shells 23 Reymond's Animal Electricity 23 Taylor's Jledical Jurisprudence 27 Unger's Botanical Letters . . 29 Vestiges of Creation 29 SITEGEEY. Adams on Reparation of Tendons 3 Do. Subcutaneous Surgery 3 Anderson on the Skin . . . . 3 Ashton on Rectum 4 Erodhurst on Anchylosis . . . . 7 Br>-ant on Diseases of Joints . . 7 Cailender on Rupture 8 Chapman on Ulcers 9 Do. Varicose Veins . . . . 9 Clark's Outlines of Surgery . . 9 Collis on Cancer 9 Cooper (Sir A.) on Testis . . . . 10 Do. (S.) Surg. Dictionary 10 Coulson on Lithotomy .. ..10 Curling on Rectum 10 Do. on Testis 10 Druitt's Surgeon's Vade-Mecum U Fergusson's Surgery 11 Gamgee'sAmputation atHip-jointl3 Gant^s Principles of Surgery .. 13 Heath's Minor Surgery and Bandaging 15 Higginbottom on Nitrate of Silver 15 Hodgson on Prostate 15 Holt on Stricture 15 James on Hernia 17 Jordan's Clinical Surgery . . 17 Lawrence's Surgery 18 Do. Ruptures 18 Listen's Surgery 18 Logan on Skin Diseases .. ..19 Macleod's Surgical Diagnosis . . 19 Do. Surgerj' of the Crimea 19 Maclise on Fractures 19 Maunder's Operative Surgery.. 20 Nunneley on Erysipelas .. ..21 Pirrie's surgery 22 Price on Excision of Knee-joint 22 Salt on Rupture 24 Sanson! on Chloroform . . . . 24 Savage's Female Pelvic Organs 24 Smith (Hy.) on Stricture .. ..25 Do. on HtemoiThoids . ..25 Do.ontheSurgerj'of theRectum 25 Do. (Dr. J.) 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