A pterigium is a pink, fleshy growth starting on the nasal side of the white of the eye and growing laterally across the cornea. It is usally confused with a cataract. With time a pterigium becomes larger, redder, inflamed, uncomfortable, unsightly and may interfere with vision. It can be removed in a simple, safe, painless operation with anesthetic eyedrops. At the end of the operation beta-radiation is administered to prevent the pterigium from growing back again. No one knows the exact cause of pterigia, but it is more common in adults exposed to sun, wind, sand, salt-spray or sawdust. They are more common in people living closer to the equator. Thus, it might help to wear dark sunglasses.