A pterygium is a raised, wedge-shaped growth that occurs on the surface of the eye. It is thought to be related to increased exposure to ultra-violet (UV) light, as it is more common in people who have lived in sunny areas. It is not cancerous, although cancers can develop in the same area of the surface of the eye.
Pterygium starts as an area of redness and thickening on the conjunctiva, usually on the inner aspect of the white of the eye. In some cases, the pterygium may extend across onto the cornea, which is the clear front window of the eye that covers the iris. If the pterygium grows towards the middle of the cornea, it should be surgically removed.