On the Restoration of Vision. 1 15 



successfully undergone the operation for cataract, and who al- 

 most uniformly require deeper convex glasses to see distinctly 

 immediately subsequent to the operation, than are necessary af- 

 terwards. That the retina and optic nerve become partially in- 

 sensible from not being exercised, and reacquire their natural 

 susceptibility when again brought into use, are facts which I 

 have so often witnessed, that 1 judged them sufliciently con- 

 firmed to insert them in my practical observations on diseases of 

 the eve ; and I have also generally observed, more particularly 

 in poor persons, who from the inconvenience attached to wearing 

 spectacles, appear to feel an objection toiheir use, that although 

 they are imal.-le to see either near or distant objects immediately 

 after the operation, without glasses, yet, after a time, they ac- 

 ([uire the power to a considerable degree of perfection, if they 

 have the patience to do without them. I cannot elucidate these 

 opinions better, than by instancing three cases which have oc- 

 curred in the extensive opportunities I have had of making si- 

 milar observations among the patients on whom I have operated 

 for the cataract. 



The fiist was a postillion who had been blind nine years in one 

 eve, and three in the other. Both cataracts were successfully 

 removed bv the operation effecting their absorption, and when 

 he resumed his employment as a postillion, he was, fron> neces- 

 sitv, obliged to wear his spectacles, not being able even to walk 

 without them ; but finding that his passengers were frequently 

 apprehensive of their safety, from being driven by a person re- 

 quiring spectacles, he bv degrees left them off altogether in the 

 daA', and in the course of twelve months he could drive quite as 

 well without as with them. At night, however, when the rays 

 of light being comparatively few in number, require the most 

 complete concentration upon the retina, to produce a sufficient 

 impression upon that membrane for the purposes of vision, he 

 still derived great advantage from the use of distant sight spec- 

 tacles. The poor fellow died of pleurisy about two years after 

 the removal of the cataracts. Had he lived, it is probable the 

 susccptiljility of the retina would have so far increased, and the 

 adjustive powers of the eye so much improved, that he would 

 have seen even at night, sufficiently well without the use of any 

 glasses. 



While at Exeter I effected the removal of cataracts in a young 

 man twenty years of age, who was born with them. The ca- 

 taracts were originally fluid, but, as is usually the case when this 

 species is suffered to remain for any long period without being 

 operated upon, the fluid part had become absorbed, leaving no- 

 thing but an opake capsule containing the grosser parts of the 

 cataract. With the right eye he could see brilliant colours, and 



H 2 perceive 



