A pterygium is a wing-shaped growth of pink or white tissue which begins in the loose conjunctiva overlying the white sclera and grows onto the cornea. The inner and outer corners of the eye are the most common areas for these to develop. Pterygia (plural) may remain small and stationary, or they may slowly enlarge; this enlargement is due to the accumulation of additional scar tissue and feeder blood vessels; they are not, however, a form of cancer. Visual loss can occur if a pterygium spreads over the cornea into the central pupillary region. Visual distortion due to induced astigmatism is common. Occasionally pterygia are accompanied by localized irritation, inflammation and redness.
It is not known what causes a pterygium, however, certain factors such as prolonged exposure to sunlight, wind, or airborne irritants (i.e., sand) have been implicated. This probably explains why pterygia are more common in southern and tropical areas as well as in desert environments. They are also seen more frequently in individuals who spend a great deal of time outdoors.
Many pterygia do not cause significant visual or functional problems and do not require treatment. Persistent irritation or progressive central growth with early encroachment on the pupillary region of the cornea is the most common reason surgical removal of the pterygium is recommended. Pterygium removal is performed in the operating room as an outpatient procedure under a local anesthetic. The procedure is somewhat analogous to peeling a postage stamp off an envelope. Most patients return to work within 1-2 days and experience quieting of the eye over a two to three week period. A pterygium sometimes will recur after surgical removal. Special techniques such as conjunctival transplantation or local chemotherapy may be used at the time of the primary surgery or when dealing with a recurrence to prevent subsequent regrowth of the pterygium.