AMAUROSIS, OR GUTTA SERENA. 147 



the same time, using any of the usual mild, stimulating eye- 

 washes, to reduce any irritation of the eye. 



There are two different operations: one to be performed 

 when the lens itself is the seat of the disease, and which is 

 called extirpation of the lens, and consists in removing it ; the 

 other, called couching, consists in passing a pointed instru- 

 ment, a couching-needle, in front of the lens, and pressing 

 down the false membrane from before the lens. 



The former operation is quite useless, as a double-convex 

 lens, or glass, would have to be worn after it, which would be 

 impracticable with the horse. The latter may be very suc- 

 cessful, and will justify having it performed. An experienced 

 oculist, or veterinary surgeon, alone can tell which operation 

 would be required; and such alone can perform it. On ac- 

 count of the retracting of the eye by the muscle, whose ofiice 

 it is to draw it back, the operation could not be performed 

 without the use of chloroform, but by administering it this 

 difficulty is entirely obviated. ' 



AMAUROSIS, OR GUTTA SERENA. 



This affection is commonly called glass-eye, and is character- 

 ized by a total loss of sight, without any known previous 

 affection of the eye. It may affect either one or both eyes. 



Sijmptonis. — The symptoms by which wq may distinguish 

 this difficulty are not very numerous, but sufficiently charac- 

 teristic. The owner or groom will first be led to suspect some 

 diffi-culty of the eye from the movements of the horse. On 

 examination the pupil (the sight of the eye) will be found 

 permanently dilated; will not contract in the strongest light; 

 the horse will take no notice of any motion toward the eye; 

 he is "stone-blind" in the affected eye or eyes. The peculiar, 

 glassy brightness of the eye renders it unmistakable. 



Causes. — Amaurosis is a palsy of the optic nerve, which 

 conveys the impressions of objects to the brain, to produce 

 the sense of sight; or of the retina, which is the broad expan- 



