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182 AMERICAN FARMER'S HORSE BOOK. 



are either too flat or too convex. A great difference may be 

 noticed in the eyes of different horses, not so much as to size 

 as their shape. 



The coastings of the eyes are not equally transparent in all 

 horses, and a similar difference exists in regard to the clear- 

 ness and refractive powers of the humors. Sometimes the 

 rays of light do not fall properly upon the retina; or, as oc- 

 casionally happens, the retina may be so small that some of^ 

 them fall outside of it. When the eye is too full or convex, 

 the rays will converge too soon, and form an image of the 

 object in front of the retina ; when it is too flat, they do not 

 converge soon enough, and their proper focus is behind the 

 retina. These conditions may all exist, while there is no 

 trace whatever of local or chronic disease of the eyes. 



Old horses are the ones most subject to dimness of vision. 

 Their eyes become too flat, and this produces far-sighted- 

 ness. The trouble with young horses is generally the reverse ; 

 they are near-sighted from the too great convexity of the 

 cornea. Either of these infirmities are likely to make a horse 

 subject to sudden starts and other disagreeable eccentricities. 

 How often may one see a near-sighted horse paying no atten- 

 tion to the approach of an object, until it is quite near, and 

 then, when he discovers it, throwing up his head with a 

 quick start, and other signs of alarm. Such an animal is 

 pretty sure to be an inveterate stumbler, from the mistakes 

 which he is always making in estimating distances. 



The eyes of some horses are never clear; the aqueous hu- 

 mor seems unnaturally thick and dark ; yet they remain in 

 the same condition, growing no worse, if they do not im- 

 prove, during a whole life-time. But a horse with such eyes 

 is not perfectly sound; for imperfect vision is always a great 

 defect. He is especially untrustworthy for the road. Great 

 care should be taken, in purchasing a horse, to look well^to 

 his eyes, and avoid being imposed upon. 



We know of no remedy for dimness of vision. The diffi- 

 culty is beyond the reach and skill of men or medicine. 



