A pinguecula is a small growth of tissue on the conjunctiva (the clear lining that covers the white part of the eye), usually on the side closest to the nose. It may be caused by a response to a chronic eye irritation or sunlight. No treatment is necessary unless it becomes inflamed or causes irritation. A pterygium is also a growth on the conjuntiva, but it also grows onto the cornea. If it grows large enough, it can interfere with vision. It occurs more often in people with extended exposure time to sunlight. When a pterygium becomes red, irritated, and affects vision, it can be removed surgically. Even with proper surgical removal, a pterygium can reoccur.