A pterygium is a non-cancerous growth of the clear, thin tissue that lays over the white part of the eye (conjunctiva). One or both eyes may be involved.

The cause is unknown, but it is more frequent in people with excess outdoor exposure to sunlight and wind, such as those who work outdoors.

Risk factors are exposure to sunny, dusty, sandy, or windblown areas. Farmers, fishermen, and people living near the equator are often affected. Pterygium is rare in children.

The primary symptom of a pterygium is a painless area of elevated white tissue, with blood vessels on the inner or outer edge of the cornea.

A physical examination of the eyes and eyelids confirms the diagnosis. Special tests are usually not necessary.

No treatment is required unless the pterygium begins to obstruct vision -- then it should be surgically removed. Protective glasses and a hat with a brim should be worn to prevent recurrences.

Most pterygia cause no problem and need no treatment. If pterygium encroaches on the pupillary area of the cornea, results are usually good after removal.

Recurrence after removal.

People with pterygium should be seen by an ophthalmologist annually, so that encroachment on the pupil can be recognized and treated before interference with vision.

Call for an appointment with your ophthalmologist if you have had a pterygium in the past and symptoms recur.

Eye protection from ultraviolet light may have a preventive effect.