What is inflammation of the cornea?

The cornea is the transparent portion of the outer surface of the eye, through the cornea enters the light. Keratitis (collective noun for a number of diseases in wich the cornea becomes inflamed) has multiple causes, and there are several forms of keratitis, like photokeratis. That is a (painful) eye condition caused by exposure of insufficiently protected eyes to the UV rays. There are also some other forms of keratitis, wich you can find on the internet, books, etc.