Recently, I came across an article in a sailing magazine, headlined "Pterygium Alert: Cruisers Beware!" It states that sailors need to watch out for a growth on the eyeball called pterygium. According to the article, it's caused by exposure to sunlight, wind and dust, and is a thickening of the corneal tissue similar to a callus. What possible problems could result from this "callus"? Is there any way to remove it from the eye?

S.

A pterygium (pronounced TER-i-gee-um) is the name for a condition in which the white part of the eye (the conjunctiva) grows onto the clear part of the eye (the cornea). A pterygium looks like a triangular "wing" of white tissue that extends onto the cornea (like a pterodactyl's wing).

People in the tropics are at greatest risk of developing a pterygium because such growths are caused by the sun's ultraviolet (UV) radiation, which is most intense at the equator. Initially, an area on the white part of the eye will begin to thicken and look like a bump. This is called a pingueculum. Most of the time, a pingueculum grows slightly but does not progress to a pterygium. However, if a person is routinely exposed to UV light, such as may be the case with sailors exposed to sunlight reflecting off the water, the white tissue can grow onto the cornea.

If a pterygium grows onto the cornea and extends into the visual field, it may cause vision loss that requires surgery to correct. Surgery involves removal of the pterygium from the cornea and excising the conjunctival portion as well. Patients face a 50 percent risk of pterygium recurrence unless doctors take additional steps to prevent regrowth. The most common additional step is removing an unaffected piece of white tissue and grafting it into the area from which the pterygium arose. Studies have shown that the "graft" technique lowers the pterygium recurrence rate to 5 percent. Other common methods of preventing recurrence include topical use of mitomycin (an drug that interferes with cell growth) or irradiation to the white part of the eye after the pterygium is removed.