Glossary:

Pterygium

A pterygium is a growth of thick tissue that covers the white part of your eye. It will usually start growing near the inner corner of the eye and may extend to the cornea towards the pupil. The causes of pterygium are not known, but it is more likely to develop in people who live in tropical climates, work outdoors, or spend a lot of time in the sun. Pterygium can be surgically removed.