214 
DEPARTMENT OF SURGERY. 
in a dark stall until the anterior and posterior chambers are re¬ 
filled. If bandages cannot be adjusted so as to obviate pressure 
upon the eye, a hood (Fig. 50) should be used instead. 
6. Diseases of the Cornea .—The structure of the cornea has 
already been mentioned, and also the diseases which may be 
benefited by paracentesis. Anatomically, the cornea may be 
considered a continuation of the conjunctiva, sclera and uveal 
tract. The conjunctiva is continued as the epithelial layer 
and anterior limiting membrane ; the sclera, as the substantia 
propria; and, from the uveal tract, the posterior limiting mem¬ 
brane and the endothelium (. Descemet's membrane ). The patho¬ 
logical importance of this is apparent when we consider the part 
involved in each individual form of keratitis and non-inflam- 
matory diseases of the cornea. 
Diseases of the cornea can be studied chemically, either from . 
their etiology or by tracing the anatomical divisions of the part 
affected. To properly treat disease of this kind both methods 
must be carefully considered, and more especially when they 
can be treated surgically ; to puncture the cornea in all the 
diseases of cornea mentioned as indications, at all times, and 
under all conditions, would not be good treatment; in all these 
cases the operator must exercise good judgment and should 
never resort to such surgical interference simply because some 
one has treated a similar case in this manner, but should do so 
with an object in view. 
(a) Pannus is a non-inflammatory vascular opacity of the 
cornea. It is sometimes confined to the superficial layers of 
the cornea ( pannus tenuis ), (which is a continuation of the 
conjunctiva and is often accompanied by trachoma, entropion 
or trichiasis, and usually results in a thickening of epithelial 
layer, and in most instances involves but a portion of the 
cornea, usually the upper ; but when the substantia propria is 
involved ( pannus crassus ) the entire surface of the cornea may 
be thickened and dense. Either of these forms of pannus sel¬ 
dom run a course without ulceration or formation of new blood 
vessels by hypernutrition, which is usually caused by the in¬ 
activity of the absorbing system. 
In the treatment of this condition,which is usually secondary, 
the first object in view is to remove the cause, and, next, to in¬ 
crease absorption. Some veterinarians have successfully treated 
these cases by evacuating the anterior chamber, while others 
have received but little benefit from the procedure. We there¬ 
fore would advise the surgeon to be somewhat reluctant in re- 
