A pterygium is a wing of proliferating scar tissue arising from the conjunctiva and adhering to the cornea. The conjunctiva is the clear membrane that covers the white part of the eye and the cornea is the clear window at the front of the eye. The scar usually appears from the side of the nose. The most common cause is associated with the outdoor life in a high UV (sunlight) environment. The light irradiation causes a breakdown in the tissues, which try to heal themselves by forming a scar. Exposure to wind also exacerbates the situation. Sometimes a secondary pterygium may occur following a chemical injury or trauma.
Typically the pterygium gets red and inflamed from time to time. There may be irritation. In many cases, however, all that is noticed is a transparent scar, which progresses slowly if at all.
In cases where the scar is active and inflamed, there can be progression over the cornea to the point where there is distortion of vision, and ultimately complete blurring if the scar crosses the pupil zone.
A small pterygium that does not get inflamed and only just crosses onto the cornea can be observed periodically. Ocular lubricants may be required for comfort, and are useful after activities that irritate the eyes.
You should always wear sunglasses outdoors, and a wide brimmed hat or cap.
The indications for surgery are as follows:
- Distortion of vision
- Recurrent inflammation
- Cosmetic issue
- Documented growth
Surgery involves removing the scar tissue from both the cornea and the white part of the eye. In order to prevent further recurrence a small graft of conjunctiva is either glued or stitched to the excision site. Sometimes at the time of surgery an anti-scarring agent (anti-metabolite) is applied to help prevent recurrence. Surgery is performed under local or general anaesthesia depending on personal circumstances.
After surgery you will need to use steroid drops for several weeks. These drops are anti-inflammatory and also help prevent recurrence.
Short-term there may be haemorrhage (unsightly but not vision threatening) on the surface of the eye which will clear after a week or so.
The graft may not take – this is rare.
There may be an infection affecting the cornea or the sclera – this is rare.
Longer term the main problem is recurrence, which may be in up to 10% of cases. Recurrence rates are affected by issues such as, previous surgery, race, age and environmental exposure.
The pterygium is excised and a graft of healthy conjunctiva is placed
in the excision site – this helps prevent recurrence.