DISEASES OF THE EYE. 



By Dr. JAMES LAW, F. R. C. V. S., 



Professor of VctcrhHirij Science, etc., Cornell U)n'versift;. 



AVg can scareelj^ overestimate the value of sound eyes in the horse, 

 and hence all diseases and injuries which seriously interfere with vision 

 are matters of extreme gravity and apprehension, for should they prove 

 permanent they invariably depreciate the selling price to a considerable 

 extent. A blind liorse is always dangerous in the saddle or in single 

 harness, and he is scarcely less so when, with partially impaired vision, 

 he sees things imperfectly, in a distorted form or in a wrong i^lace, and 

 when he shies or avoids objects which are commonplace or familiar. 

 When we add to this that certain diseases of the eyes, like recurring- 

 inflammation (moon blindness), are habitually transmitted from parent 

 to offspring, we can realize still more fully the importance of these mala- 

 dies. Again, as a mere matter of beauty, a sound, full, clear, intelli- 

 gent eye is something which must always add a high value to our 

 equine friends and servants. 



THE EYEBALL. 



A full description of the structure of the eye is incompatible Avith 

 our i)rescribed limits, and yet a short description is absolutely essen- 

 tial to the clear understanding of what is to follow. 



The horse's eye is a spheroidal body, flattened behind, and with its 

 posterior four- fifths inclosed bj'an opaque, white, strong fibrous mem- 

 brane (the sclerotic), on the inner side of which is laid a more delicate 

 friable membrane, consisting mainly of blood-vessels and pigment 

 cells (the choroid), and that in its turn is lined by the extremely deli- 

 cate and sensitive exi)ansion of the nerve of siglit (the retina). The 

 anterior fifth of the globe of the eye bulges forward from what would 

 have been the direct line of the sclerotic, and thus forms a segment of 

 a much smaller sphere than is inclosed by the sclerotic. Its walls, 

 too, have in health a perfect translucenc}^ from wliich it has derived 

 the name of t rem spar ent cornea . This transparent coat is composed, 



