42 



for different distances, would lead to perverted nutrition and 

 possibly to inflammation, in the capsule, the lens, the ciliary 

 ligament or ciliary bodies. The nutrition of the lens may 



Total , Cataract (after Armat 

 entire pupil a grayish white color 



Fig. 12. 



:'T (after Armatage). — The opaque lens gives the 

 lyish white color. 



also be perverted by inflammation primarily in the lens itself 

 or from extension of inflammation in the iris, the ciliary 

 bodies or the ciliary ligament, to the lens. Active inflam- 

 mation in the lens or the surrounding parts, (from wounds, 

 injuries or other diseases) generally leaves inflammatory 

 products or deposits iu tho substance of the lens or its cap- 

 sule, which form permanent opacities. Strokes on the head 

 that produce sudden concussion are said to cause opacities in 

 the lens. There are many cases of cataract, the cause of 

 which cannot be determined; but the most prolific cause of 

 cataract in the horse is periodic opthalmia (moon blindness). 

 Straining the eyes to see objects iu imperfectly lighted barns 

 or stalls, no doubt, plays an important part in producing cat- 

 aracts as well as other eye diseases. 



Occasionally small spurious cataracts of the capsule dis- 

 appear, because of the great activity of the cells of the cap- 

 sule. But opacity of the lens substance very rarely disap- 

 pear ; because changes in its structure take place very slowly 

 for it contains no blood vessels or nerves. 



Sometimes small gray specks may remain unchanged ; but^ 

 as a rule, the little gray star like opacity gradually increases 

 unil total lenticular or capsular opacity appears. 



