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A pterygium is a triangular growth of abnormal tissue that invades the
cornea. Its development is not related to injury or inflammation. 90%
of pterygia are located nasally. Both eyes are frequently involved
but often only one.
The pterygium can advance to involve the visual axis causing marked loss of visual acuity.
The pterygium can be distinguished from a pingueculum, which is a small-elevated yellowish mass, which can become inflamed. The pterygium grows in the interpalpebral fissure (that is the exposed part of the eye) as an elevated fleshy mass of the conjunctiva.
SYMPTOMS
Burning, irritation, tearing and a foreign body sensation may accompany the growth of a pterygium onto a cornea. Astigmatism may be induced and may lead to decreased vision. As the apex of the pterygium approaches the visual axis, glare and reduced contrast sensitivity appear.
In severe cases symblepharon formation (adhesions) may limit ocular motility and result in diplopia, which is double vision.
For poorly understood reasons the pterygium growth may stop at any stage. It may remain so for the rest of the patient's life or at a later date again start growing.
There is a worldwide distribution of pterygium but it is more common in warm, dry climates. Studies have shown a strong relationship between ultraviolet radiation and the formation of pterygia.
A study in Australia identified a number of risk factors:
- Living in the tropics
- Working in a sandy outdoor environment
- Not wearing sunglasses
- Not wearing a hat
Local drying of the conjunctiva and tearfilm abnormalities may also be contributing factors.
The highest incidents occur between the ages of 20-49 and rarely occur under the age of 15.
TREATMENT
The decision to remove a pterygium is dependant on the patient's symptoms and the interest in cosmetic improvement. Recurrences may be more frequent in young adults. Virtually all post-operative recurrences occur within the first year after surgery and often within 6-8 weeks. With recurrence there is a higher incidents of growth into the visual axis and of symblepharon formation.
MEDICAL TREATMENT
Eye drops such as preservative free lubricants, vasoconstrictors and mild cortico steroids can relieve the symptoms. Some believe ultraviolet-blocking spectacles can prevent progression.
SURGICAL
The pterygium is removed surgically and the method depends on the surgeon doing the operation.
