A pterygium is a small growth on the white part of the eye that extends onto the cornea and grows in a triangular shape towards the pupil. They typically occur on the nasal side of the eye. These lesions are benign and grow very slowly. If they cause chronic irritation and redness, or interfere with your vision, then they can be surgically removed. The surgery involves removing the abnormal conjunctiva and placing a tissue graft over the area where the pterygium was removed.