DISEASES OF THE EYE 37 



dinary dilation of the pupil, which becomes immov- 

 able, and the eye has a bright glassy appearance. 

 This is caused by a paralysis of the optic nerve, 

 or its retinal expansion. 



Cures in this disease are very few in the horse. 

 Indeed, we doubt if ever the cure of a confirmed case 

 of gutta serena, or glass eye, has been effected. 



GENERAL BLINDNESS AND IMPERFECT VISION. 



No subject is of greater importance than the state 

 of a horse's organs of vision, and ought to occupy 

 the first attention of a purchaser ; for blindness, or 

 a partial defect in the eyes, may lead to many un- 

 pleasant consequences to the proprietor, whether in 

 riding or driving. It will require considerable know- 

 ledge of the anatomical construction of the eye to 

 enable any one to judge correctly of its perfection 

 or defects. 



Independently of the beauty of a prominent eye, 

 it is of much importance that the cornea should 

 possess considerable convexity ; but this must have 

 a limit. If very prominent, the rays of light will 

 be too convergent, which will cause indistinct vision ; 

 on the other hand, if the cornea be small and flat, 

 the rays may not be sufificiently convergent, and 

 consequently will render the vision imperfect. A 

 horse is unsafe with either of these defects, both in 

 riding and driving, as he is certain to start at 

 objects which suddenly present themselves, or he 

 may quickly bolt round, and in either case may 

 over-balance the rider, or upset a vehicle. 



The cornea should, therefore, be moderately 

 convex, perfectly transparent, and totally free from 

 all opacity or cloudiness over its entire surface. The 

 best method of examining this organ is to place the 



