CHAPTER VIII 



DISEASES OF THE CORNEA 



The cornea is one of the most important structures 

 of the globe. It is perfectly transparent, and is one of 

 the refractive media next in importance to the lens. 

 Diseases of this body, resulting in opacity, cause a 

 greater percentage of blindness than diseases of all 

 other portions of the eye combined. 



It is composed of five layers, and a knowledge of these 

 layers (see Anatomy), with the ability to distinguish 

 the seat of the disease, will assist one materially in his 

 prognosis. 



Keratitis is an inflammation of the cornea. It may 

 be local and confined to a small area, or it may be general, 

 involving the whole corneal structure. Superficial 

 keratitis, in which the epithelium only is involved, may 

 undergo complete repair, with much damage to the re- 

 fractive value. When Bowman's membrane is destroyed 

 it is never replaced. When localized destruction of the 

 true corneal layer occurs it is filled in by cicatricial tissue 

 quite different in arrangement from normal elements. 



In severe types of keratitis there is also a congestion 

 of the conjunctiva, and often an inflammation of the iris 



88 



