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 common 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 block vision -- then it should be removed with surgery. Wear protective glasses and a hat with a brim to prevent the condition from returning.

Most pterygia cause no problems and do not need treatment. If a pterygium affects the cornea, results are usually good after it is removed.

A pterygium can return after it is removed.

People with pterygium should be seen by an ophthalmologist each year, so that the condition can be treated before it affects vision.

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

Protecting the eyes from ultraviolet light may help prevent this condition.