A pterygium is a benign growth of tissue on the surface of the eye. This growth is often triangular in shape and, if left untreated, can extend across the pupil obscuring vision, or causing the surface of the eye to alter shape and “warp” resulting in vision blurring.
Exposure to excessive amounts of ultra-violet light is thought to be the most significant cause of pterygia, which are more common in people living in sunny areas and in people whose jobs expose them to ultra-violet light (eg: farmers, arc welders). The risk of pterygia is higher in ozone layer-depleted regions of the world, such as New Zealand, due to reduced ultra-violet-light filtering. Other factors that may cause the development of pterygia include environmental irritants (eg: wind, dust, chemicals, air pollution) and hereditary factors.
Signs and symptoms
A pterygium (pronounced “te-ridge-e-um”) starts as redness and thickening in the corner of the eye – usually the corner closest to the nose. The growth can extend across the surface of the eye towards the iris (the coloured part of the eye). Often a person may notice the formation of a pterygium but may not experience any other symptoms. If other symptoms are experienced, they may include:
- Eye redness and inflammation
- A gritty feeling in the eye
- A feeling that there is a foreign object in the eye
- Dryness of the eye due to reduced tear production
- Blurring of vision if the corneal surface is altered or “warped”
- Obscuring of vision if growth encroaches across the pupil.
A pterygium can usually be diagnosed by its distinctive appearance and symptoms. However, in the early stages it may be confused with similar conditions such as pinguecula. For an accurate diagnosis to be made a referral to an ophthalmologist (eye specialist) may be recommended.
Treatment depends on the size and nature of the pterygium, the symptoms and whether vision is affected. There are two main ways a pterygium can be treated.
Eye drops may be used to reduce redness and irritation. Where dryness of the eye is a problem, artificial tears are used to keep the eye well lubricated.
Surgery may be recommended when vision is affected or symptoms are particularly problematic. During surgery, the pterygium is carefully removed and a section of the conjunctiva (the transparent skin that covers the surface of the eye) is taken from under the eyelid and is grafted onto the area where the pterygium was. Surgery is performed using a local anaesthetic and takes approximately 30 minutes to perform. Eye drops and eye ointment are usually prescribed after the surgery to prevent infection and assist with healing. It is possible for pterygia to recur after surgical removal, though this only happens in a small percentage of cases.
In order to prevent pterygia forming, or to reduce the risk of a pterygium recurring, the following measures are recommended:
- Use sunglasses that block out ultra-violet light (close-fitting, wrap around styles are best)
- Wear sunglasses and a hat when outdoors
- Avoid exposure to environmental irritants eg: smoke, dust, wind and chemical pollutants
- Use appropriate eye safety equipment in work environments.
Lica, L. (2006) Pinguecula and pterygium. The Gale Encyclopedia of Medicine. Third Edition. Jacqueline L. Longe, Editor. Farmington Hills, MI. Thompson Gale.
Cullen, A.P., Ozone depletion and solar ultraviolet radiation: ocular effects, a United Nations environment programme perspective. (2011). www.ncbi.nlm.nih.gov/pubmed/21670695
O'Toole, M.T. (Ed.) (2013) Mosby's Dictionary of Medicine, Nursing & Health Professionals. (9th ed.) St. Louis: Elsevier Mosby
Last Reviewed – 17 April 2013