Keratitis is an inflammation (with or without infection) of the clear front layer of the eyeball (cornea). It may be a serious threat to vision.

The cornea has 4 distinct layers and is less than a millimeter thick. Normally it contains no blood vessels or pigment and is transparent. Disease or injury may cause cloudiness, pigmentation, vessel ingrowth and ulcerations.

Causes of keratitis include injuries, irritation, immune or allergic reactions, infections and birth defects.
Keratitis is described according to the corneal layers affected and the shape and nature of the abnormality. Some types include superficial, interstitial, deep, ulcerative, pigmentary, punctate, dystrophic, allergic, and degenerative keratitis.

Treatment varies according to type and severity of the keratitis. Laboratory tests and surgery may be required. It is important to prevent further irritation to eye(s) from contaminated water, wind, sprays, smoke, and trauma.