DISEASES OF THE EYE AND ITS APPENDAGES 121 



(lamellEe) of the lens itself. Tliey looked upon cold, injury, and, in 

 particular, periodical attacks of intlammation ot the eyes as the chief 

 causes of cataract. 



Bracken and Gibson, in 1737, and James White, in 1802, trace the 

 disease to repeated attacks of inflammation, and by the terms of their 

 description they leave no doubt in the mind of the reader that the disease 

 to which they trace the origin of cataract is the periodic ophthalmia of later 

 times. Particularly they note that when the cataract is fully formed the 

 ophthalmic disease ceases to appear at the accustomed times. 



Gibson remarks that the disease known as moon-blindness, which is 

 one of the terms applied to periodic ophthalmia, was really nothing but 

 the prognostic of the breeding of cataracts, and he adds that he does not 

 remember to have met with a case, excepting in the eyes of a horse, which 

 had been called moon-blindness. James White also speaks of heredity as a 

 cause of moon-blindness, and that of the most intractable sort. 



Notwithstanding the various causes from which cataract is said to result, 

 there is no doubt that it sometimes appears without the animal giving 

 any evidence of active disease. The writer has known several instances of 

 this kind, where cataract developed without any obvious cause and without 

 any symptoms of inflammation being presented. 



The question of treatment has always given rise to a good deal of differ- 

 ence of opinion. In the time of Drs. Bracken and Gibson the operation of 

 couching, as it was called, was very well known to them, and they agree that 

 the disease cannot be cured by any outward application of remedies, but 

 only by a surgical operation, which they admit is not applicable to the 

 lower animals on account of the impossibility of adjusting an artificial 

 lens to compensate for the loss of the actual one. In this respect, how- 

 ever, the modern oculist may claim some little advance. Dr. Eandolph of 

 the Johns Hopkins hospital published some time ago an account of the 

 removal of two cataracts in a dog. The writer comments on the general 

 lielief that artificial lenses are absolutely necessary, and goes on to state that, 

 according to his own experience, their use has been much overrated, and he 

 quotes cases of his patients who obtained, after some considerable practice, 

 a fair degree of vision without the use of spectacles. In support of his 

 opinion he mentions eases of a reproduction of the lens in perfect form 

 after complete removal. Dr. Eandolph's own operations on dogs suggest 

 the possibility of restoring a certain degree of visual power to animals 

 which are perfectly blind. In the case of the dog the operation of the 

 removal of the lens was performed under chloroform on one eye, and in 

 three weeks the sight was so far restored that the dog was able to make his 

 way rapidly through a passage made by placing chairs for the purpose, and 



