412 CHAPTER 57. 



cataract without any perceptible periodical attacks of iuflammation. The 

 Author has also known the same to occur in a young troop horse. He 

 recollects the case of a troop horse purchased in a sound state at five 

 years old, and which was found to be affected at eight years old with 

 lenticular cataract in both eyes, though it had never shown outwardly 

 the slightest sign of disease in those organs. 



850. Capsular Cataract. 



Capsular cataract proceeds from the same causes and is formed in much 

 the same way as lenticular ; but for some reason not very easy to explain 

 the deposit fixes itself on the inner surface of the capsule instead of in 

 the lens. If the lens be examined by a good reflected light, it will be 

 found to be clear behind its capsule. 



In some cases capsular cataracts form from causes other than attacks 

 of specific ophthalmia. In such, it is probable that the deposit on the 

 capsule may be absorbed, and the eye restored to its pristine state. 



851. Capstdo -lenticular or Interstitial Cataract. 



The third variety of true cataract, known as Capsulo-lenticular or 

 Interstitial cataract, is found in the form of an opaque fluid between 

 the lens and its capsule. 



By taking a side view of the eye, these cataracts are easily distinguished 

 from lenticular, because the transparency of the lens can then be seen 

 behind the opaque deposit. 



852. Absorption of Cataracts. 

 True lenticular cataract is very rarely, if indeed it is ever absorbed. 

 Capsulo-lenticular are occasionally, and capsular cataracts are somewhat 

 more frequently absorbed in time. 



853. Degree of injury to vision caused by true Cataract. 



The degree of injury to vision caused by true cataract is very uncer- 

 tain. Probably it depends more on its position than on its size. A small 

 speck, for instance, in the centre of the lens will obviously be more in- 

 jurious than a larger opacity on the side. The best plan in each case is 

 to test the horse's vision by taking him up to an obstacle, and then to 

 notice how far his sight is imperfect. 



Horses which see imperfectly are very apt to shy, and on this account 

 many horsemen prefer an animal totally to one partially blind. Again it 

 may be remarked that blind horses generally step high, so as to enable 

 them to clear unseen obstacles. They instinctively select the hard road, 

 and are afraid of soft ground. The sense of hearing also becomes more 

 acute, and is shown by the almost constant movement of the ears. 



854. No cure for true Cataract. 

 Veterinary science knows no cure for true cataract. We cannot avail 

 ourselves of those operations which in the human subject are so valuable, 



