PEKIODKJ OPHTHALMIA. 



341 



cular coats to contract. If the eye remains weak, it may be stimu- 

 lated by the application of a few drops of — 



Nitrate of silver ... 

 Or, sulphate of zinc 

 Or, alum... 

 Water 



2 grains. 

 1 oz. 



Periodic Ophthalmia, or Moon Blindness. 



CAUSES AND NATURE. — This somewhat rare disease appears 

 to be brought on by bad sanitary arrangements; and, according 

 to Percivall, by the injurious influences of wet, marshy pastures 



Sclerotica/..^ 



ChcroicL' 



Retina/... 



— Eyelids 



._ . CoJijvuictxvcv 

 "Eyelash' 



— Iris 



--ComecL 



- -Aqueous hzurunvr 

 ■Crystalline lens 



hts 



"-Eytlash/ 

 EyeUd/ 



Fig. 140. — Longitudinal and vertical Isection of eye. 



on which horses are reared. In its production, hereditary pre- 

 disposition plays a large part. For instance, using, for stud pm-- 

 poses, stallions whose eyes wore affected, was formerly a frequent 

 cause of blindness among Irish horse-s. The frequency of its occur- 

 rence has diminished in direct proportion to the improvement 

 which has been made in stable life, especially as regards ventilation, 

 and the consequent removal of the irritating presence of ammonia. 

 As I have never seen a case of periodic ophthalmia in horses 

 which had been always kept under healthy conditions, I look upon 

 it as a disease due to chemical or mechanical irritation, and not 

 as an infective malady. 



