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II. — On the Cause and Cure of Cataract. By Sir David Brewster, K.H., F.R.S. 



(Read 16th January 1865.) 



My attention was called to the subject of Cataract, in consequence of having, 

 about forty years ago, experienced an incipient attack of that complaint, and 

 studied its progress and cure. 



While engaged in a game at chess with Sir James Hall, who was a very slow 

 player, I amused myself in the intervals with looking at the streams of light 

 which radiated from the flame of a candle in certain positions of the eyelids. In 

 one of these observations I was surprised by a new phenomenon, of which I did 

 not immediately see the cause. The flame of the candle was surrounded with 

 lines of light, of an imperfectly triangular form, some parts of which were deeply 

 tinged with the prismatic colours. Upon going home from the chess club, this 

 optical figure was seen more distinctly round the moon, and of course it appeared, 

 with more or less brightness, round every source of light. 



Having been engaged in examining the structure of the crystalline lens in 

 animals of all kinds, I soon discovered the cause of the phenomenon which I have 

 described. The laminae of the crystalline lens had separated near its centre, and 

 the separation had extended considerably towards its margin. The albuminous 

 fluid, the liquor Morgagni, which so wonderfully unites into one transparent 

 body, as pure as a drop of water, the mass of toothed fibres which compose the 

 crystalline lens, had not been sufficiently supplied, and if this process of desicca- 

 tion had continued, the whole laminae of the lens would have separated, and 

 that state of white opacity induced, which no attempt has ever been made to 

 remove. 



The continuance of this affection of the lens was naturally a subject of much 

 anxiety, and I never entertained the slightest hope of a cure. My medical 

 friends recommended the use of what were then called Eye Pills, but having 

 received no benefit from them, and having learned from experience the sympathy 

 between the eye and the stomach, I used every day, and copiously, the Pulvis 

 salinus compositus, and at the end of about eight months, when playing at chess 

 in the same apartment, I had the happiness of seeing the laminaa of the lens 

 suddenly brought into optical contact, and the entire disappearance of the lumi- 

 nous and coloured apparition with which I had been so long haunted. 



In speculating on the process by which the crystalline lens is supplied with 

 the necessary quantity of fluid, it occurred to me that it might be derived from 

 the aqueous humour, and that cataract might be produced when there was too 

 little water and too much albumen in the fluid which filled the aqueous chamber. 



VOL. XXIV. PART I. D 



