lis 0« Ihe Restoration of Vision, 



fully exemplified in the third case detailed, it in general re- . 

 quires a considerable time to restore by exercise the want of 

 sensibility occasioned by its having been long dormant. 



I have, however, lately seen another similar instance in a young 

 man thirty years of age, born with cataracts : with one eye, as 

 in the above case, he never had seen more than to distinguish 

 brilliant colours, and perceive light from darkness. The frag- 

 ments of the cataract having sjjontaneously become depressed 

 immediately on its being divided, he instantly saw light much more 

 strongly than he had done before ; on tlie following day he saw 

 all the objects around him, and at the ex])iration of a fortnight, 

 when the eye had recovered itself, he could, with the assistance 

 of glasses, distinctly discriminate the minutest objects, even the 

 second and minute marks on my watch dial. 



The third case is entirely opposite in its bearing to the two 

 former. About seven years since, 1 operated upon a young gen- 

 tleman born with partial cataracts. The centre of the crystal- 

 line lens was opake in both eyes, but the circumference in each 

 was transparent, which afforded him an indistinct but very use- 

 ful vision, he being able to read small Greek character, and to 

 see distant objects, althougli not as far or as distinct as other 

 people, yet sufficiently for general use. I removed the whole of 

 the lens by the operation for absorption, when with the assistance 

 of properly adjusted glasses, \\p saw with his best eye both near 

 and distant objects to the utmost extent of his expectations and 

 wishes ; with the other, the retina of which had become insensi- 

 ble from never having been in the habit of exercising it, he could 

 see but very little. After the operation he habituated himself 

 constantly to use spectacles for distant as well as for near ob- 

 jects, and he is now at the end of seven years unable to avoid 

 running against persons, or the furniture of a room, if he at- 

 tempts to cross it without them; whereas, with spectacles, he 

 sees sufficiently to have become an expert shotsman. There 

 can be no doubt that the inabilitv of this gentleman to see ob- 

 jects, has arisen from his not bringing the adjusting powers of 

 the organ into action, in consequence of habitually using his two 

 kinds of spectacles which effected the necessary refraction of the 

 rays of light to see both near and distant objects, without oc- 

 casioning any e:.ertion of the eye ; whereas if he had felt the 

 same necessity of doing without them soon after the operation, 

 as described in the case of the postillion, he would imquestion- 

 ably have succeeded equally well. It is also evident that by the 

 removal of the crystalline lens, he lost the power which he pre- 

 viously possessed, of adjusting his eyes to different distances, al- 

 though their partial opacity prevented his seeing cither near or 

 distant objects as well as ather persons, and which power, owing 



to 



