The conjunctiva is the mucus membrane that covers the front of your eye. A pterygium is a raised, triangular or wedge-shaped, benign (not cancer) growth of conjunctiva tissue. It usually occurs on the side of your eye nearest your nose.

A pterygium can grow over the cornea (the transparent dome at the front of your eye). It can grow large enough to affect your vision.

Causes of a pterygium

A pterygium usually develops if you have been living in a hot, dry climate. This might be a response to your eye’s long-term exposure to sunlight, or chronic eye irritation from the dry climate.

Symptoms of a pterygium

As the pterygium develops, it might change the shape of the cornea, making it curve more. This causes astigmatism, which affects how your eye focuses. When the pterygium has grown towards the centre of your cornea it will affect your vision.

Other symptoms include:

  • irritation
  • redness
  • tearing (eyes watering)

How a pterygium is diagnosed

The ophthalmologist (eye doctor) will be able to see the pterygium, just by looking at your eye.


Treatment depends on your symptoms. If the pterygium is small or growing, you might be prescribed eye drops or ointments to help with any redness or irritation.

You might be advised to have surgery to remove the pterygium if:

  • it is causing constant eye irritation
  • it is causing problems with your sight
  • you are unhappy with how it affects your appearance

Not having treatment

It is unlikely that the pterygium will get worse if you are living in the UK. If you are planning to move to a hotter, drier climate then it could get worse. Surgery is the only way to remove the pterygium. 

Resource number: 2168/VER6
Last reviewed: August 2022
Next review due: August 2025 

Contact us

If you have any questions or concerns, please contact the nurses in the eye day care unit at St Thomas’ Hospital.

Phone: 020 7188 6564, Monday to Friday, 7.30am to 6pm, and Saturdays 9am to 12 midday.

Outside these hours, please contact the on-call eye doctor via the main switchboard, phone: 020 7188 7188.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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