AMAUROSIS— BUCK EYE. 387 



is sacrificed can be replaced externally by means of convex glasses : 

 but in the horse, nothing of the kind can be done. Hence, it is 

 useless to dream of effecting any improvement in this disease ; and 

 if both eyes are the subject of cataract, the horse is incurably 

 blind. But supposing there is a cataract in one eye only, is the 

 other sure to go blind, or may a reasonable hope be entertained of 

 its remaining sound ? Here the history of the iisease must be 

 examined before any opinion can be formed. If the opacity fol- 

 lowed an accident, there is no reason for concluding that the other 

 eye will become diseased ; but if it came on idiopathically, either 

 preceded by inflammation or otherwise, there is great risk of a 

 repetition in the sound eye. Nevertheless, instances are common 

 enough of one eye going blind from cataract, while the other re- 

 mains sound to the end of life ; and those are still more frequent 

 in which the one sound eye continues so for six or seven years. 



AMAUROSIS. 



This is a palsy of the nervous expansion called the retina, 

 produced by some disease, either functional or organic, of the optic 

 nerve, which is generally beyond the reach of our senses, in ex- 

 amining it after death. The symptoms are a full dilatation of the 

 pupil, so that the iris is shrunk to a thin band around it, and is so 

 insensible to the stimulus of light, in confirmed cases, that, even 

 when the eye is exposed to the direct rays of the sun, it does not 

 contract. In the early stages, this insensibility is only partial ; and 

 though there is such complete blindness that the horse cannot dis- 

 tinguish the nature of surrounding objects, yet the pupil contracts 

 slightly, and the inexperienced examiner might pass the eye as a 

 sound one. The unnaturally large pupil, however, should always 

 create suspicion; and when, on closing the lids and re-opening 

 them in a strong light, there is little or no variation in its size, the 

 nature of the disease is at once made apparent. The treatment of 

 amaurosis must depend upon the extent to which it has gone, and 

 its duration. If recent, bleeding and a seton in close proximity 

 to the diseased organ will be the most likely to restore it. Some- 

 times the disease depends upon a disordered condition of the std- 

 mach, and then a run at grass will be the most likely means to 

 restore both the affected organs to a sound state. Generally, how- 

 ever, an amaurotic eye in the horse may be considered as a hope- 

 less case. 



BUCK EYE. 



A BUCK EYE is, strictly, rather a congenital malformation than a 

 disease ; but practically, in reference to the utility of the animal, 

 it matters little. It depends upon an excess of convexity in the 

 cornea, by which the focus of the eye is shortened too much, the 

 image being thus rendered indistinct as it falls on the retina. No 

 treatment can be of the slightest use. 



