A pterygium (plural: pterygia) is a triangular fleshy growth of the conjunctiva, the thin translucent membrane that covers the white of the eye. Although it is a non-cancerous growth, it progressively enlarges and grows onto the adjacent cornea, the clear transparent front covering of the eye. When this occurs, it distorts the cornea, causing astigmatism and disturbing vision. In very advanced cases, it can cover the pupil and cause blindness.
The exact cause of a pterygium is unknown. It is, however, associated with long-term exposure to ultraviolet (UV) rays from sunlight as well as irritants such as dust or wind. It is also more common in people with dry eyes.
A pterygium may involve one or both eyes. It most commonly occurs on the exposed conjunctiva between the upper and lower eyelids close to the nose.
In its early stages, a pterygium causes no symptoms other than its appearance. As it grows, patients may experience:
- Foreign body sensation
- Blurring of vision
A pterygium can be diagnosed by an eye care professional with the naked eye or after an eye examination under high magnification. In addition, a series of tests such as Visual Acuity Test, Keratometry, Slit-lamp Examination and Anterior Segment Photography can be performed to determine the visual impact of the pterygium.
Treatment may not be necessary in the early stages of this condition when a patient does not have any discomfort. In mild cases of irritation and inflammation of the pterygium, lubricating eye drops or ointment and a short course of steroid eye drops may improve symptoms.
If the pterygium causes persistent discomfort or has encroached onto the cornea to threaten or interfere with vision, it can be surgically removed. Surgical excision of a pterygium can also be performed for cosmetic reasons.
There are several surgical techniques currently in use to remove a pterygium. The most modern technique is pterygium excision with conjunctival grafting which has the lowest risk of recurrence after surgery.
Pterygium excision involves removing the abnormal conjunctival tissue from the white part of the eye (sclera) and the cornea in patients with encroachment of the pterygium into the cornea. It is usually combined with conjunctival grafting, an additional procedure in which a healthy piece of conjunctiva is removed from underneath the upper eyelid of the same eye and grafted over the area where the pterygium has been excised. This grafting procedure is done to reduce recurrence of the pterygium. Attachment of the graft can be done with sutures (by stitching) or with the use of fibrin glue. Pterygium excision is usually performed as an outpatient procedure under local anaesthesia.
After the surgery, antibiotic and steroid eye drops are prescribed to prevent infection and reduce inflammation. Painkillers are usually prescribed to reduce the discomfort and pain associated with the surgery.