Pterygium

Definition:

A triangular fold of tissue that grows from the conjunctiva onto the cornea of the eye.

Causes, incidence, and risk factors:

A pterygium is a nonmalignant tumor that frequently grows on the nasal side of the eye. It may occur in both eyes. The cause is unknown, but it may be the result of exposure to ultraviolet light. Risk factors are exposure to sunny, dusty, sandy, or windblown areas. It is rare in children.