The cornea is the clear, protective outer layer of the eye that plays a key role in vision by refracting light as it enters the eye. The curvature of the cornea helps determine how well your eye can focus on objects that are near or far. Vision can be distorted if the cornea becomes damaged from disease, infection or injury. There are groups of conditions which affect the cornea called "dystrophy," which are inherited, and "degeneration," which are progressive.

Symptoms
Following infection or injury, the cornea will often heal well with no long-term problem. However, if there is significant tissue damage, a variety of symptoms may occur, including pain, blurred vision, redness, tearing, and light sensitivity. In severe cases, there is actual visual loss due to scarring and distortion of the cornea.

Treatment
Bacterial infections are treated with antibiotics in eyedrop form. However, there are viral and fungal infections of the cornea which do not respond well to medications. As noted above, corneal dystrophies and degenerations are progressive in some cases and do not respond to any medication. In cases of severe scarring-whatever the cause-a corneal transplant may be necessary to restore vision.