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Keratoconus is a gradual change in the shape of the cornea that causes it to become irregular and cone-shaped.

The condition usually begins between the ages of 10 and 25. Both eyes are usually affected, causing major changes in vision and requiring frequent changes in the prescription for eyeglasses or contact lenses.

Contact lenses often correct the vision problems better than eyeglasses, but sometimes the change in corneal shape is so severe that contact lenses either cannot be worn or cannot correct vision. In severe cases, corneal transplantation (see Transplantation: Corneal Transplants and Why They Usually Work) may be needed to restore vision. Some newer alternatives to transplantation may become more available in coming years. They include insertion of corneal ring segments (objects that change the shape of the cornea to help correct refraction) and ultraviolet light treatments that strengthen the cornea.

Last full review/revision October 2008 by Melvin I. Roat, MD. FACS