92 OPHTHALMOLOGY FOR VETERINARL\NS 



Some types of ulcers are more severe than others; 

 they have special characteristics and are known by 

 special terms. 



The crescentic ulcer occurs near the Hmbus or sclero- 

 corneal margin, and from its location is also known as 

 marginal keratitis. It begins as an interrupted Hne of 

 infiltration beneath the epithelium. Small pustules arise 

 along its course, which coalesce. The epithelium soon 

 breaks down and a continuous ulcer results. As a rule 

 it is confined to the superficial layers and may spread to 

 the center of the cornea, leaving in its wake a thin cica- 

 trix. It may terminate favorably in a few days, though 

 its progress is often protracted, and months may elapse 

 before recovery takes place. It most frequently occurs 

 in the aged. 



The Serpiginous Ulcer. — This is one of the most 

 destructive types of sloughing ulcer. It is character- 

 ized by a grayish-yellow disk-like patch, centrally 

 located, with an opacity about the border and somewhat 

 elevated. Numerous radiating striae invade the corneal 

 surface; the anterior layers break down and eventually 

 a large ulcerated area filled with pus results. There is 

 usually much pain connected with it in and about the 

 eye, though in some cases the pain is not so intense as 

 the pathologic process would lead one to believe it 

 might be. Iritis and iridocycKtis with hypopyon very 

 frequently occur. In many cases the ulcer perforates 

 the cornea, allowing the escape of aqueous and pus. 



