CATARACT. 125 



fourteen solipedes and one dog, by extraction, couching, and divi- 

 sion of the lens. Five horses and one mare, subjected to extrac- 

 tion, did not recover their sight. Of five other horses, one female 

 ass, and one bitch, couched, one horse in whom the lens remained 

 couched saw pretty well for several days after the operation ; but 

 ten days afterwards no longer could distinguish surrounding ob- 

 jects. The same thing happened to the ass, whose turned out a 

 milky cataract. Another horse, whose cataract likewise was milky, 

 and who saw sufficiently well immediately after the operation to 

 direct his own steps, the following morning could not see at all. 

 In one horse and one mare the operation of division of the lens was 

 practised ; but it proved impossible, either before or after the dis- 

 placement, to break up the lenticular body. 



GOHlER has, in few words, detailed his method of procedure for 

 the operation of couching. The horse being cast and secured, and 

 his head steadily maintained by an assistant, and the double specu- 

 lum of Tenon used to confine the eyelids, while the cartilage nicti- 

 tans has been retained by a blunt hook, the transparent cornea has 

 been punctured with an oculist's straight knife, at the distance of a 

 line or two from its circumferent border, on the outer side. The 

 knife has then been carried through the aperture of the pupil upon 

 the lens, and the lens depressed by it. To depress has proved easy ; 

 but to keep the lens down, out of the axis of vision, extremely dif- 

 ficult*; the moment the knife was withdrawn the lens rising again. 

 The eye made no movement after it had become transfixed by the 

 knife ; and so every opportunity was given to keep the lens 

 couched as long as was deemed requisite. 



Leblanc, however, must be regarded as our great authority and 

 best guide in these matters. He uses a bent needle, with a plain 

 or convex back and cutting sides, whose concavity describes the 

 figure of two oblique planes, united in the middle by a line slightly 

 salient, extending to the point of the instrument, the handle being 

 turned in the direction of the convexity of the blade. A simple, 



* This arises from the elasticity of the compressed vitreous humour. On 

 this account, that form of displacement which is called RecUnation^ which 

 consists in a tu?ming over of the lens into the middle and towards the bottom 

 of the vitreous humour, is to be preferred to simple depression. 



