A pterygium is a wedge-shaped scar-like growth on the surface layer of the eye, called the conjunctiva, that extends to the cornea. The conjunctiva is a thin layer covering the whites of the eyes. The cornea is the clear windshield covering the colored part of the eye.
A pterygium spreads from the conjunctiva onto the cornea [See figure 1]. Pterygia usually grow over the edge of the cornea nearest the nose and are more common as we age. Pterygia are more commonly seen in those who live in areas of the world nearest the equator. Pterygia are associated with excessive exposure to the sun, wind, or sand (especially during childhood and teen years).
Fig. 1: A pteryguim is a wing-like growth that extends onto the cornea.
WHAT IS THE CAUSE OF A PTERYGIUM?
The most likely cause of a pterygium is damage and irritation to the conjunctiva by the sun's ultraviolet rays. A pterygium contains both damaged blood vessels and fibrous connective tissue. Pterygia do not spread from person to person, they are not contagious.
WHAT ARE THE EFFECTS OF A PTERYGIUM?
Pterygia are usually small and early on cause no complaints. Over time, they can cause dryness, redness, burning, itching and/or an unacceptable appearance. Larger pterygia can cause blurred vision by changing 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 more completely, pterygia can cause loss of vision.
HOW CAN A PTERYGIUM BE TREATED?
Artificial tears usually help with irritation and burning caused by pterygia. Anti- inflammatory drops may be used for more significant symptoms. If vision is affected or if the pterygia become large, surgery can remove the pterygium, but regrowth is possible. To prevent the regrowth of the pterygium, surgeons may move normal conjunctiva from another part of the eye to the area where the pterygium was removed, or use an anti-metabolite drug (like mitomyocin-C) or amniotic membrane to cover the area where the ptergium was removed.
what are the other conditions that can look like pterygia?
A pterygium may be confused with a pingueculum. A pingueculum looks like a yellowish patch or bump on the conjunctiva and also comes from damage to the conjunctiva, but it does not grow over the cornea like a wing.
Other growths of the conjunctiva in children include a freckle (nevus), melanoma or lymphoma. The diagnosis of a pterygium should be confirmed by an ophthalmologist.
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 pterygia.