Pterygium means "wing" and refers to a wing-like growth on the surface of the eye. The pterygium (growth) spreads from the conjunctiva over the cornea [See figure 1]. The conjunctiva is the mucous membrane covering the whites of the eyes (sclera) and the cornea is the clear windshield of the eye covering the colored part of the eye. Pterygia are more common in areas of the world nearest the equator. They are associated with early exposure to the sun (especially during childhood and teen years).
A pterygium may be confused with a pingueculum. A pingueculum looks like a yellowish patch or bump on the white surface of the eye. It grows on the conjunctiva, similar to a pterygium, but does not grow over the cornea. A pingueculum is a benign degeneration of the conjunctiva that occurs as people get older. Similar to a pterygium, a pingueculum is caused by damage due to exposure to ultraviolet light (sun).
Fig. 1: A pteryguim is a wing-like growth that spreads over the cornea.
What is the cause of a pterygium?
The most likely cause of a pterygium is damage to the conjunctiva by the sun's ultraviolet rays. Pterygia usually grow over the edge of the cornea nearest the nose. Pterygia do not spread from person to person.
What are the effects of a pterygium?
Pterygia are usually small and have no harmful effects. They sometimes cause dryness, redness, burning, itching and/or an unacceptable appearance. Larger pterygia can cause blurred vision by altering the shape of the cornea, producing astigmatism. Some pterygia grow over the center of the cornea blocking light from entering the eye. When they grow over the cornea, pterygia can cause loss of vision.
How can a pterygium be treated?
Artificial tears usually relieve irritation and burning caused by pterygia. Anti-allergy drops or even anti-inflammatory drops may be used for more significant symptoms. If vision is affected or if the pterygia become large, surgical excision may be indicated. Regrowth of the pterygium after removal is a common late complication. To prevent the regrowth of the pterygium, surgeons may transplant conjunctiva from another part of the eye to the area where the pterygium was removed, or use anti-metabolite drugs or amniotic membrane.
Other cancerous and non-cancerous growths of the conjunctiva, such as squamous cell carcinoma, may resemble pterygia. The diagnosis of a pterygium should be confirmed by an ophthalmologist.
What are the other conditions that resemble pterygia?
How can a pterygium be prevented?
Prevention starts in childhood with protection of the eyes from the sun. Using brimmed hats and sunglasses with UV protection may help prevent pterygium development.