362 DISEASES OF CATTLE. 



PTERYGIUM. 



This term is applied to a fleshy colored membrane, triangular in 

 form, which most frequently grows from the inner angle of the eye 

 and extends over the cornea, thus interfering with vision. It may 

 grow from the outer angle, or even from the superior or inferior 

 hemisphere of the eyeball. The figure is invariably that of a tri- 

 angle, with its base on the white of the eye, and its apex more or less 

 advanced over the cornea toward its center. 



The distinguishing characteristics are the constancy of the tri- 

 angular fomi, and the facility with which the whole of it may be 

 taken hold of with a pair of forceps and raised into a fold on the 

 cornea. Every other kind of excrescence attached to this membrane 

 continues firmly adherent to it, and can not be folded and raiser! from 

 the surface of the cornea in any manner whatever. 



Treatment. — Raise the fold and dissect it away from all points of 

 attachment. 



TKICHIASIS (inversion OF THE EYELASHES ). 



In the simplest form the eyelashes bend inwardly, touching the 

 eyeball, causing irritation and simple conjunctivitis. It may be also 

 associated with entropion. 



Treatment. — The oiffending eyelashes should be cut off or pulled 

 out. In cases where the natural growth of the eyelashes is directed 

 inward an operation similar to that for entropion becomes necessary. 



ENTROPION (inversion OF THE EYELID ). 



In inversion of the eyelid the eyelashes soon irritate the anterior 

 face of the cornea and produce more or less inflammation and opacity. 

 The inversion may be due to the growth of a tumor within or with- 

 out the lid, to abscess, laceration, or injury, causing the lid to lose its 

 natural conformity to the eyeball, ulcerations, etc. Surgical inter- 

 ference, in either case, becomes necessary to restore the lid to its 

 natural direction. 



ectropion (e%t:rsion of the eyelid). 



This serves to injure the eye by permitting dust and other foreign 

 substances to gain admission to the eye, and interferes with the 

 natural removal of such substances. 



Treatm£nt. — A delicate surgical operation — the removal of an 

 elliptic section of the palpsebral conjunctiva — may remedy the defect. 



