A pterygium is a wedge-shaped growth of thickened tissue that covers the white part of the eye. Typically, a pterygium starts growing near the inside corner of the eye. It is not a cancer and will not develop into cancer. Composed of conjunctival tissue, a pterygium may:

  • grow large enough to cover the pupil, which can blur or obstruct vision
  • cause irritation, tearing and discomfort
  • interfere with the comfortable wearing of contact lenses
  • pull on the cornea and distort its shape, which can cause astigmatism
  • look red and unattractive.

In these cases, the pterygium may have to be surgically removed.

The exact cause of a pterygium is not known. Genetic factors may be important as pterygia tend to run in families. Exposure to ultraviolet rays from the sun is thought to play a major role. Risk factors include:

  • living in a tropical environment
  • working outdoors
  • spending a lot of time in the sun.


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