DISEASES OF THE EYE AND ITS APPENDAGES. 359 



To remove opacity, after the inflammation has subsided, apply a 

 few drops of the following solution twice a day: lodid of potas- 

 sium, 15 grains; tincture sanguinaria, 20 drops; distilled water, 2 

 ounces; mix. 



Sometimes keratitis exists in a herd as a transmissible disease, 

 spreading like infectious conjunctivitis. Calomel, applied to the eye, 

 is especially useful in such cases. 



ULCERS or THE CORNEA. 



An ulcer comes from erosion or is the consequence of the bursting 

 of a small abscess, which may have formed beneath the delicate layer 

 of the conjunctiva, continued over the cornea; or, in the very sub- 

 stance of the cornea itself, after violent keratitis, or catarrhal con- 

 junctivitis. At other times the ulc«r is produced by bruises, 

 scratches, and other direct injury of the cornea. 



Symptoms. — The ulcer is generally at first of a pale gray color, 

 with its edges high and irregular, discharges instead of pus an acrid 

 watery substance, and has a tendency to spread widely and deeply. 

 If it spreads superficially upon the cornea, the transparency of this 

 membrane is lost; if it proceeds deeply and penetrates the anterior 

 chamber of the aqueous humor, this fluid escapes, the iris may pro- 

 lapse, and the lens and the vitreous humor become expelled, thus 

 producing a destruction of the whole organ. 



Treatment. — It is of the greatest importance, as soon as an ulcer 

 appears upon the cornea, to prevent its growing larger. The corrod- 

 ing process must be converted into a healthy one. For this purpose 

 nothing is more reliable than the use of solid nitrate of silver. A 

 stick of nitrate of silver should be scraped to a point; the animal's 

 head should be firmly secured; an assistant should part the lids; if 

 necessary, the haw must be secured within the corner of the eye and 

 then all parts of the ulcer should be lightly touched with the silver. 

 After waiting a few minutes the eye should be thoroughly washed out 

 with a very weak solution of common salt. This operation generally 

 has to be repeated once more at the end of three or four days. If 

 healthy action succeeds, the ulcer assumes a delicate fleshy tint, and 

 the former redness around the ulcer disappears in proportion as the 

 ulcer heals. 



In superficial abrasions of the cornea, where there is no distinct 

 excavation, this caustic treatment is not needed. The eye should be 

 bathed with sulphate of zinc, 30 grains to half a pint of soft water, 

 several times a day, and protected against exposure to cold air and 

 sunlight. Excessive ulceration sometimes assumes the form of fun- 

 gous excrescence upon the cornea, appearing to derive its nourish- 

 ment from loops of blood vessels of the conjunctiva. Under these 



