A pterygium is essentially scar tissue on the surface of the eye, which we believe is due to sunlight and irritation. Such tissue is called a pterygium when it extends onto the cornea, or window of the eye.
When small, pterygii can lead to discomfort or redness and can also be cosmetically displeasing. When larger, they can threaten vision by growing towards the centre of the cornea.
Small pterygiums can often be managed with artificial tear drops and sunglasses. As they increase in size, surgery may be necessary to remove the pterygium.