Pterygium is a growth of white-coloured tissue over the cornea, the clear front window of the eye. It usually occurs on the inner side of the cornea (the same side as the nose). Pterygium is not a cancer and never spreads to other parts of the body.
Pterygium is a growth of white tissue over the cornea. The edge of the pterygium is close to the pupil but has not yet covered it (left). An unusually large Pterygium (right).
The cause is unknown but some are probably due to exposure to the ultraviolet light in strong sunshine. This may be the reason that pterygia are more common in hot countries such as Australia, India, South Africa etc.
The pterygium may be noticeable as a white mark on the eye and may be intermittently inflamed, red and uncomfortable. If untreated some pterygia gradually grow over the centre of the cornea so causing loss of sight.
Although pterygium may result from excessive sunshine there is little medical evidence that avoiding sun- shine or wearing ultraviolet-absorbing sunglasses either reduce the likelihood of developing pterygium or slow progression once it has begun. This may be because pterygium results from sunshine exposure during early childhood so action taken later in life is ineffective. If a pterygium becomes inflamed it may be soothed with lubricating eyedrops such as hypromellose or Geltears. If it is very inflamed I sometimes prescribe a weak steroid eye drop such as FML or Predsol to use for a day or two.
The only permanent cure for a pterygium is surgery. This is a delicate operation in which the pterygium is removed and replaced by a graft of normal tissue taken from the white part of the eye underneath the upper eyelid. It takes 30-45 minutes and can be done under general or local anaesthesia. The graft greatly reduces the chance of the pterygium recurring, but this still happens in about 10-20% of cases.
If the pterygium does recur the operation may need to be repeated, either with a new tissue graft or a substance derived from human placenta called amniotic membrane which has strong healing properties. However surgery is only needed if the pterygium is large or getting bigger quickly. It is safe to simply keep the majority of them under observation.