go OPHTHALMOLOGY FOR VETERINARIANS 



suppurative and the non-suppurative. The suppurative 

 includes all ulcers, and those forms which are induced 

 by infection from without. The non-suppurative type 

 includes pannus, the vesicular and punctate forms, 

 interstitial and all forms of keratitis, which are, as a 

 rule, caused by constitutional disease. 



Ulcer of the Cornea. — As the cornea is the most ex- 

 posed portion of the eye, an ulcer is one of its most com- 

 mon affections. Ulcers range in degree from the sim- 

 plest form, minute in size, to the destruction of a large 

 area of corneal tissue, and their course is influenced, to a 

 great degree, by the' organism causing the ulcer, its 

 early treatment, and the constitutional resistance. 



Simple ulcers begin with a small infiltration, which 

 eventually breaks down. They are usually clean, though 

 they may have a slight grayish base. They may be ir- 

 regular in shape, though usually circular. They have, 

 under proper treatment, a tendency to heal readily 

 without advancing. 



In severe types the inflammation extends backward 

 into the deep structures or spreads over a large area in 

 the anterior layers. Deep ulceration may invade the 

 whole thickness of the cornea. When perforation takes 

 place there is a loss of aqueous with a prolapse of the 

 iris into the wound. This remains impacted, and be- 

 comes adherent at the point of prolapse. At this stage 

 resolution usually begins, and there is a gradual filling 

 in or restoration of tissue, later marked by the presence 



