134 CANINE MEDICINE AND SURGERY 



Keratitis Inter stitialis 



Keratitis interstitialis is a far more serious con- 

 dition, since it involves the corneal parenchyma. 



Symptoms. — It begins with irregularly rounded 

 whitish dots which usually appear in the center of 

 the membrane. There is haziness, ciliary infection, 

 and a marked formation of new vessels. At times 

 the opacity is so completely confined to the in- 

 terstitial lamina that the cloudy portion of the mem- 

 brane looks as if it were covered. As the diseas'.^ 

 progresses the opacities in the lamellcc grow larger 

 by fusion until the whole cornea may become opaque. 

 There is intense ciliary injection, a constant flow 

 of tears, and great photophobia. The amount of 

 vascularization varies largely in different cases. Ves- 

 sels extend in from the superficial and deep loops, 

 until at times the entire membrane becomes of a 

 dark red tint. Their formation generally occurs in 

 that part of the periphery that is nearest the densest 

 opacity. When the disease subsides the cornea 

 clears from its periphery, the central opacities being 

 the last to disappear. The complications are iritis, 

 with the formation of posterior synechije (adhesion 

 of iris to lens), choroidal degeneration, and retinitis. 



Suppurative Keratitis 

 {Abscess of the Cornea) 



Suppurative keratitis in its various forms is due 

 to injury and infection or is secondary to disease 

 afifecting other tissues of the eye or body. 



The most common form is marked by ulceration 

 of the cornea, the ulcer sometimes destroying all the 

 layers and causing evacuation of the aqueous humor. 

 Usually, however, the ulcerative process stops at 

 the membrane of Descemet, which from interocular 

 pressure bulges out from the cornea, causing the 

 condition known as staphyloma. 



