KERATITIS 533 



distemper of the dog and oat, is not infrequent. Purulent 

 infection of the conjunctiva (palpebral, scleral, corneal) may 

 lead to ulceration. The microorganisms most frequently 

 found are streptococci, staphylococci, pneumococci, and other 

 pyogenic germs. 



The infection producing ulceration is no doubt in many 

 cases carried by the blood to the cornea, and by the lymph 

 into the cornea. Many diseases which reduce corneal 

 resistance predispose to ulceration, such as chronic constitu- 

 tional diseases, and some infectious diseases. In birds 

 suppuration of the lacrimal passages and conjunctiva leads 

 to ulceration as is frequently noted in epitheliosis. This 

 form commonly leads to perforation of the cornea. 



Symptoms. Corneal ulcers vary considerably in size, form 

 and depth. Any portion of the cornea may be the seat of 

 one or more of them. Jn most cases, however, ulcers are 

 found at or near the center of the cornea. In form they are 

 mostly round with well defined, sharp borders as if cut out 

 with a sharp instrument. In other cases their form is 

 irregular. The base of the ulcer may be flat, concave, or 

 convex; rough, vascular, or infiltrated. The cornea sur- 

 rounding the ulcer is usually turbid, and secondary ulcers 

 not uncommonly develop. Uleeration of the cornea accom- 

 panying dog distemper often occurs suddenly, tends to spread 

 rapidly and not infrequently leads to perforation in a few 

 days. Photophobia, lamination, and congestion of the 

 adjacent structures are nearly always present. Frequently 

 a copious discharge of pus occurs from the affected eye. 

 Pain may or may not be a prominent symptom, depending 

 upon the cause of the ulcer and to what extent other struc- 

 tures of the eye are involved. 



Course. The usual course is chronic. Some cases require 

 several weeks for complete disappearance. The ulcer may 

 disappear without trace, or it may lead to perforation, or 

 cicatrization and permanent opacity. 



Prognosis. Ulceration of the cornea is always serious. 

 Perforation, panophthalmitis, or opacity often follow it. Its 

 chronicity and tendency to recurrence make the prognosis 

 always guarded. 



