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What is a pterygium?

The cornea (crystal window of the eye) is 12mm wide and overlies the iris (coloured part of the eye) which is seen through the transparent cornea.  The cornea is surrounded by the sclera (the white of the eye). Overlying the white of the eye is the conjunctiva (a transparent filmy tissue like the membrane lining the mouth).

A pterygium comes from the Greek word for ‘wing’ and translates to “wing of tissue”. It is an overgrowth of tissue from the white of the eye over onto the cornea (crystal window of the eye). It normally presents on the “nose” side of the eye although occasionally, in less than 1 percent of cases, it may come from the “ear” side.


It usually presents in patients over the age of 20, and particularly in people who have worked or spent a lot of time in the sun. This is not a cancer and is a localised disturbance on the surface of the eye.

Usually a pterygium will remain stationary after a period of growth during which time it may extend 1, 2, 3 millimetres or more onto the cornea. It is impossible for anyone to predict whether a particular pterygium is likely to grow further and over what time.  Very occasionally it may cross the line of vision.

In some cases, where there is redness, irritation or the vision is affected, surgery may be the appropriate method to treat this condition. It is a good idea to have any pterygium ‘watched’ every year or two by an optometrist or ophthalmologist who can assess its growth.

Prevention is better than cure:  Always wear a hat, sunglasses and avoid excessive periods in the sun.