30 



OPHTHALMOLOGY FOR VETERINARIANS 



in various portions of the lid indicate the presence of 

 tumors. If these are movable and free from the skin, 

 a meibomian duct is occluded, resulting in the forma- 

 tion of a chalazion. If the Hd is edematous, look for a 

 point of local induration. This condition may accom- 

 pany heart and kidney lesions, and some cases of 

 trichinosis. 



The conjunctiva should be transparent, showing the 

 sclera beneath it. If it is congested, note carefully the 

 location. An injection about the margin of the cornea 

 indicates a cyclitis; a localized injection over the site 

 of a muscular insertion is a symptom of localized tenon- 

 itis; an injection of the peripheral portion, with large 

 radiating vessels, suggests glaucoma. 



A severe chemosis suggests either a general tenonitis 

 or some affection of the orbital tissues. It sometimes 

 occurs with a purulent conjunctivitis. 



The cornea under normal conditions should be trans- 

 parent. If it is hazy, determine whether this is super- 

 ficial or deep. If the epithelium is intact, and the reflex 

 of a window-sash on the corneal surface is not bent or 

 broken, the trouble lies posterior to BoAvman's membrane. 

 It may be due to interstitial disease or to a turbid aque- 

 ous and deposits on the posterior corneal layer. 



The pupils should be of the same size, though rarely 

 there is a sHght difference normally. A large pupil in 

 one eye indicates paralysis of the sphincter muscle, the 

 use of a mydriatic, or glaucoma. A small pupil indi- 



