130 OPHTHALMOLOGY FOR VETERINARIANS 



from embolism or thrombosis of its vessels. The latter 

 become very small or obliterated, though the remaining 

 portion of the retina may appear normal. 



Rupture of the retina is the result of injuries, princi- 

 pally contusions of the eyeball. "Cases of isolated lacera- 

 tion of the retina are extremely rare. The retina is much 

 harder to tear than the chorioid, since in rupture of the 

 latter the retina is generally found to be uninjured" 

 (Duane). 



Glioma. — Because of the structure of the retinal tis- 

 sue glioma is the only growth the retina is subject to. 

 For a long time it has been known as "amaurotic cat's 

 eye," from the fact that the eye is blind, and the fundus 

 reflex looks like that from the tapetum of the retina of 

 the cat's eye in the dark. A glioma is a very malignant 

 tumor and occurs in the young. If not early removed, it 

 soon extends to the optic nerve and brain and results 

 fatally. Besides extending backward, it grows forward 

 and laterally into the tissues of the orbit. The globe is 

 much enlarged and ugly ulcerations may take place. 

 It may attack one or both eyes. It is one of the most 

 malignant and fatal diseases of the eye with which we 

 have to deal. 



Diseases of the Chorioid 



Because of the close connection with the retina 

 these two coats are nearly always affected when one or 

 the other is first inflamed. This is known as a retino- 



