PTERYGIUM

wing-shaped fold of membrane, an abnormal growth that develops from the inner or the outer (the nasal or the temporal) corner of the eye toward its centre; the growth obscures vision if it encroaches upon the pupil. The membrane is firmly attached at its base to the conjunctiva (the mucous membrane that lines the eyelid) and in its central portion to the white of the eye (the sclera). Pterygium results from exposure to bright sunlight, wind, and dust. Treatment is surgical removal of the membrane.