A pterygium is a ‘wing of tissue’ that grows onto the cornea.
It is thought to be caused by UV exposure, particularly the amount you received in childhood.
A pterygium can affect your vision if it grows large enough to cross the visual axis (the centre of the pupil) or if it causes significant astigmatism. (Astigmatism is where the cornea is shaped more like an egg or rugby football, rather than a perfect sphere.) Sometimes they can cause annoying irritation symptoms because they disturb the spread of the normal tear film or just look red and unsightly.
Small pterygiums that don’t bother you only require good UV protection with wrap-around sunglasses and the use of lubricant drops. Large sized pterygiums that show accelerated growth, cause significant irritation or bother you with their appearance, can be surgically removed.
Make sure that if you decide to have surgery for your pterygium you choose a surgeon with a special interest in the disease. These surgeons use a technique that has a minimal risk of the pterygium growing back, called a recurrence, and can guarantee an excellent cosmetic result.