​Here’s another reason why you should be careful to shield your eyes from sunlight when you spend time outdoors: Prolonged exposure to ultraviolet (UV) radiation from the sun can cause an eye condition known as pterygium.

"A pterygium is a reddish, triangular or wing-shaped eye growth. In its early stages, it is mostly harmless, but with time it can grow over the central cornea and affect vision," explains Dr Cordelia Chan, Visiting Senior Consultant at Singapore National Eye Centre (SNEC), a member of the SingHealth group.

Although the exact causes of pterygium remain unknown, UV rays from the sun have been proven to be a contributing factor.  "Exposure to long hours of sunlight outdoors and dry, dusty conditions seem to play an important role," says Dr Chan.

More men than women suffer from pterygium, but this is perhaps due to the fact that men tend to take on jobs that involve more sun exposure, such as construction work, and engage in outdoor sports more.

Symptoms of pterygium

A pterygium can occur in one eye, but most patients get it in both, with one eye sometimes being more affected. The slow-growing, benign lesion usually starts in the inner corner of the eye and may remain so for several years. Symptoms of pterygium include:

  • A whitish growth with prominent blood vessels on the inner or outer corner of the eye
  • Persistent redness and irritation
  • Dry eyes 
  • Occasional tearing
  • A sensation of having a foreign body in the eye

"When the pterygium progresses, it grows towards the cornea," says Dr Chan. "This growth may cause cornea scarring and exert a force on the cornea surface, leading to induced astigmatism. In advanced cases, the pterygium can cover the entire cornea, causing significant visual blurring."

Most times, the diagnosis of pterygium is simple and clear-cut. Dr Chan says: "Your doctor will be able to confirm the diagnosis by just a simple examination of the eyes. In more advanced cases, investigative tests may have to be performed to determine the effect of the pterygium on the eye."

Treating pterygium

For a start, your ophthalmologist may prescribe eye drops and ointments to soothe the redness, discomfort and inflammation.

"While this can provide some relief, it will not stop a pterygium from growing larger," says Dr Chan. "How fast a pterygium grows varies from patient to patient – some can have the condition for years before the lesion is large enough to affect vision."

Generally, surgical removal is considered when a pterygium is cosmetically obvious, or when it causes blurred vision or refractive errors like astigmatism.

After surgical removal, the bare area is covered with the patient’s own conjunctiva, in a procedure called conjunctival autografting. The tissue is taken from the same eye and attached using sutures or a special adhesive known as fibrin glue. This procedure is safe and very effective and results in a good cosmetic outcome.

After surgical removal and conjunctival autografting, the risk of a pterygium growing back is generally low, but the surgery is technically demanding, and good outcomes are very technique- and surgeon-dependent. Thus, the recurrence rates vary from surgeon to surgeon, adds Dr Chan.

Protect your eyes

Investing in a good pair of sunglasses not only protects you from pterygium, but other eye diseases as well.

"Choose carefully as some sunglasses don’t offer the right protection," says Dr Chan. "Make sure the sunglasses you buy can block 100 per cent of UV light."

Brief Facts

At SNEC, 400 to 500 pterygium surgeries are performed each year. Pterygium excision with conjunctival autografting is the treatment of choice, performed in 97 per cent of all pterygium surgeries. With this procedure, recurrence rates are generally 6 percent in primary pterygia and 10 percent in recurrent pterygia.

Ref: T12