Keratitis affects the cornea and is a relatively common eye condition, particularly in those who wear contact lenses. The cornea is the protective film layer at the front of the eye. When it develops a scratch or small abrasion, bacteria can cause an infection to take hold. Scratches can occur from rubbing your eye too hard, trauma or putting contacts in without proper care. Keratitis responds well to treatment when addressed early, but if you ignore keratitis you could experience permanent sight damage.