Generalities:

Keratitis is inflammation of the cornea, the clear, dome-shaped tissue at the front of the eye, which covers the pupil and iris. Keratitis may or may not be related to an infection. The cause of non-infectious keratitis can be a relatively minor injury, for example from wearing contact lenses for too long or from the presence of a foreign body inside the eye. Infectious keratitis can be caused by bacteria, viruses, fungi, and parasites.