342 DISEASES OF THE EYES. 



image is due to the fact that the rays of light become refracted on 

 passing through the lens. If the candle be moved from right to 

 left, the first and second images will move in the same way, while 

 the third will go from left to right ; and vice versa. Wlien the 

 cataract is complete, it will naturally prevent the formation of the 

 third image: Old cataracts have a pearly white appearance. 

 Newly formed ones are bluish in colour. 



The operation for cataract, namely, the removal of the more or 

 less opaque lens from the eye, would probably ^ve good results in 

 the horse ; for men and dogs which have been operated upon, 

 generally recover their sight sufficiently for all ordinary pui-poses 

 of locomotion in the open, even without the aid of glasses. One of 

 the best methods of operating for cataract consists in (1) applying 

 a 10 per cent, solution of the hydrochlorate of cocaine to the 

 cornea to deaden pain and dilate the pupil ; (2) making an incision 

 through the upper portion of the cornea ; (.3) pressing the lower 

 part 'of the eyeball with the fingers,. so as to- displace the lens, and 

 force it out through the pupil and towards the opening in the 

 cornea ; (4) removal of the lens through the incision ; and (5) 

 dressing the part. The operation should be performed under as 

 perfect antiseptic precautions (p. 70) as possible, and, in all cases, 

 by a skilful veterinary surgeon. 



Cataract is, of course, an unsoundness (Higgs v. Thrale, 18th 

 Feb., 1850). 



Turning-in of the Eyelashes. 



This irritating action on the part of the eyelashes often causes 

 inflammation of the eyes, and can be best removed by snipping 

 off the offending hairs with scissors. The eyes can be bathed 

 with warm water, in which a little salt (a teaspoonful to a pint of 

 water) has been dissolved. As long as the irritation lasts, the eyes 

 should be protected from light. 



lATorm in the Eye. 



This is caused by the presence of a thread-like worm in the 

 aqueous humour of the horse's eye. According to the observations 

 made at Karnal and Saharanpur by Dr. Lingard, this parasite 

 averages about an inch in length, the female being slightly longer 

 than the male. It is presumably the immature (unmarried) form 

 of the filaria equina (filaria papulosa), which is sometimes found 

 in the peritoneal cavity (p. 114) of horses. This disease is rarely 

 met with, except in India, where it is frequently seen in some 

 districts. 



