Pterygiums and pinguecula are benign ocular surface growths caused by wind, dust and ultraviolet light . The thin mucous membrane that coats the exterior of the eyeball is called conjunctiva . Like the skin on your fingertips, conjunctiva can grow callouses in response to the elements. Pinguecula are conjunctival callouses that grow adjacent to the cornea, usually at 3 or 9 o'clock axis. They usually take open a yellowish color and are composed of thickened conjunctiva, but also contain calcium deposits.
Pterygiums can start out as pinguecula, but can grow as an independent entity as well.
Pterygiums are wing-like growths that extend from conjunctiva and grow onto the cornea in the form of a wing. Pterygiums can cause irregular astigmatism, warping the cornea, or can grow big enough to block light entering the eye. Pterygiums are easily removed by placing a small spatula beneath them and removing the tissue without harm to the cornea. Usually there is a small amount of corneal scarring after pterygium removal. These growths can be prevented by wearing UV blocking sunglasses and using artificial tears for surface dryness.