A pterygium is a flesh growth that invades the cornea (the clear front window of the eye). It is an abnormal process in which the conjunctiva (a membrane that covers the white of the eye) grows into the cornea. Pterygiums may be small or grow large enough to interfere with vision and commonly occur on the inner corner of the eye.
The exact cause of a Pterygium is not well understood. Pterygiums occur more often in people who spend a great deal of time outdoors, especially in the sun. Long-term exposure to sunlight (especially UV rays) and chronic eye irritation from dry dusty conditions seem to play an important causal role.
Despite proper surgical removal, the pterygium may return, particularly in young people. Surface radiation or medications are sometimes used to help prevent recurrences. Protecting the eyes from excessive UV light with proper sunglasses and avoiding dry, dusty conditions may help.