On the Restoration of Vision. 1 17 



the edge of the capsule, where it was less opake than hi its cen- 

 tre. In the passage of the rays of light through this portion of 

 the capsule, it is evident, very little, if any refraction, could take 

 place, and it therefore required the adjusting powers of the eye 

 to be exercised in order to enable him to see near and distant 

 objects previous to the operation, quite as much, if not more 

 than if the lens had been actually removed. 



Thus, then, that j)ower which usually takes a patient six or 

 twelve months to acquire after the removal of the lens in ordi- 

 nary cases, was possessed in this previously to the performance 

 of the operation. 



The small space at the edge of the capsule, through which 

 alone the light was capable of making its way to the retina, ex- 

 plains the necessity of the patient turning his back to the light 

 in order to effect a dilatation of the pupil ; for when he faced 

 the light, from the contraction of the pupil, the iris covering the 

 greater part of the space in the capsule through which the light 

 passed, necessarily occasioned a still greater diminution of vision 

 than he previously experienced. 



The same cause accounts also for his being obliged to hold 

 small objects in an oblique direction, and for his seeing but three 

 or four letters at a time; for had the part of the capsule through 

 which the light passed, been in the centre instead of at the edge, 

 and also been of a lartje extent instead of being confined, he 

 would consequentlv have seen objects straight forwards, and have 

 possessed the power of taking in a much larger extent of vision. 

 The opinion that the latter effect was occasioned by the small 

 space through vvhich the light had to pass, is confirm.ed by my 

 having generally observed, that where the pupil is naturally 

 small, the field of vision is proportionally circumscribed. In one 

 instance of a patient who came to me after he liad undergone 

 a number of operations for cataract, in a pul)lic institution, I 

 found the pupil so much contracted as to render it dangerous for 

 him to walk in the streets by day, and entirely to incapacitate 

 him from doing so alone, at night. After forming an artificial 

 pupil of a proper size, he was enabled to see even the nails of his 

 fingers when the arms were extended to the utmost at right an- 

 gles with the body, nearly as distinctly as he could before I 

 operated upon him, when placed immediately before his eye, and 

 he now sees to walk at night as well as other persons'^. 



With respect to that eye of my late servant with which he had 

 never seen previous to the operation, and the retina of which so 

 quickly acquired its susceptibilitv, it certaiuly was a very unusual 

 circumstance ; for, as I have already observed, and as will be 



• Sec Plate II. and case 10. ii) mv work on Diseases of the Eye. 



H'3 fully 



