3"8 2 VETERINARY LECTURES 



the aqueous humour has been rendered opaque— in fact, nearly milky 

 white— from excessive sexual exertion. The animal must not be 

 used in the meantime, but be kept perfectly quiet in a dark loose-box, 

 and the eyes bathed for fifteen to twenty minutes several times a day . 

 with cold water. 



640. Cataract is a pearly white appearance, or opacity, of the 

 crystalline lens, or its capsule, or both. It may result from external 

 injury to the eye, or from frequent attacks of inflammation, or periodic 

 ophthalmia ; again, it may be congenital, and appear in one or both 

 eyes. The whole, or only part of the lens may be affected, and 

 various names are accordingly given to it, such as lenticular cataract — 

 when the lens itself is the seat of the affection ; capsular cataract — 

 when only the capsule is affected ; and cap sulo -lenticular — when both 

 are implicated. Old dogs seem to be the greatest sufferers, and in 

 these it generally comes on gradually. In the human subject the 

 lens can be removed and suitable glasses substituted, but in the 

 domestic animals treatment is of little use. When the eye is injured, 

 or undergoing severe inflammation, the great point is to use every 

 endeavour to prevent a cataract forming. 



641. In examinations of horses for soundness, it is of the greatest 

 importance that the eyes be carefully examined, as cataract causes 

 partial or complete blindness. The horse must be taken into a dark 

 place, and the eye examined with a lighted candle ; if the eye is 

 correct, the pupil will contract gradually on the light being presented, 

 a clear, deep, black-blue, liquid appearance will be seen beyond the 

 pupillary space, and the image of the light from the candle be reflected 

 in three distinct places. On moving the candle to and fro, the 

 reflected lights move at the same time ; but if cataract be present, 

 the pupil remains stationary, and a pearly white substance is seen, 

 filling up the pupillary opening. 



642. Amaurosis, or glass-eye — blindness without any visible 

 cause — is, strictly speaking, not a disease of the eye itself, but a 

 derangement of the ' optic nerve,' producing partial or complete loss 

 «of sight. The eye appears to be fuller, brighter, and more brilliant 



