Aesthetically displeasing but usually harmless is the surfer’s eye, also known as a pterygium. This triangular thickening of tissue creeping from the whites of your eye over the transparent cornea is a common side effect of ultraviolet exposure. And though a pterygium is considered to be benign (non-cancerous), there’s a little fact you should know about.
Is a Pterygium Cancerous?
No, pterygia are considered to be a degenerative condition and not cancerous, but they do share a lot of features with UV-related cancers, specifically one known as ocular surface squamous neoplasia (OSSN). Shared risk factors between pterygia and OSSN include:
- UV exposure
- Chronic inflammation of the eye’s surface
- Infection with the human papilloma virus (HPV)
The development of a pterygium and OSSN are also remarkably similar, from UV exposure, to damage at a cellular level, the cells’ response to DNA damage and inflammation, as well as their attempt to repair and adapt. All of which lead to the abnormal growth of tissue known as dysplasia. At this step, the dysplastic cells of your conjunctiva have an important decision to make – will I be a pterygium when I grow up, or will I be cancer?
About OSSN
Ocular surface squamous neoplasia is a malignant (cancerous) growth found on the cornea, the transparent dome at the front of your eye, and the conjunctiva, which is the membrane covering the whites.
During an eye exam, an OSSN can appear as a fleshy, flat or raised whitish growth with a blood supply. This, coincidentally, is quite similar to the presentation of a pterygium. It can develop just on the conjunctiva, on the cornea, or straddle both areas of the eye.
OSSN are typically slow-growing and can usually be managed quite effectively with surgical removal or potent medications. In rare cases, ocular surface squamous neoplasias have been known to spread throughout the eyeball and invade sinuses or the eye socket, so early detection is important.
Distinguishing Pterygia from OSSN
Fortunately, the rate of an unexpected OSSN diagnosis after sending a surgically removed pterygium for analysis is quite low. In the USA, this surprise diagnosis ranges from about 0.3-1.7%. Other countries with higher UV exposure, such as Australia, have a rate of OSSN masquerading as pterygia closer to 10%.
This means that the likelihood that your surfer’s eye is actually a cancer is extremely low, but you also don’t want to be in that 1.7% and not know it. Any new growth on your eye should be assessed by an eyecare professional. Both OSSN and pterygia aren’t usually painful but can cause some irritation or the feeling of a particle stuck in your eye. They can also both interfere with your vision either by inducing astigmatism or because they’re growing across the cornea.
An eyecare professional, such as an ophthalmologist or an optometrist, will assess your eye under a slit lamp microscope. They look for characteristics that aren’t typical of a good ol’ pterygium, which raises suspicion of a cancerous mass. An OSSN can be conclusively diagnosed through a histopathological examination, which puts cells taken from the growth under a high-powered microscope to look for dysplastic changes. Other methods of diagnosing OSSN include:
- The use of certain dyes that stain abnormal cells
- Anterior optical coherence tomography (AOCT), a handy piece of imaging technology that can provide a cross-sectional view of the growth, including what’s happening under the surface
Do I Need Surgery for Pterygium?
Pterygium can usually be safely monitored until it causes you issues such as irritation, inflammation and redness, or visual disturbance. However, it is important to check in regularly with your eyecare professional to keep an eye (so to speak) on that pterygium. Rapidly growing pterygia, an appearance that deviates from the typical wedge-shape, or irregular blood vessels should raise suspicion that this pterygium may not be all that it seems.
Pterygium surgery is a straightforward procedure under local anesthetic. Your surgeon will cut and peel away the pterygium, then cover the excision site with a tissue graft. This approach helps to reduce the risk of the pterygium returning. If your pterygium demonstrated some suspicious characteristics, your surgeon may send the tissue away for histopathological analysis.
How a section of UV-irradiated tissue makes the choice between becoming a pterygium or a cancerous growth, no one really knows. But ultimately, despite similar underlying pathological pathways and cellular reactions, a pterygium decides to be just a non-cancerous, non-invasive, and aesthetically displeasing growth. And while there’s no need for alarm if you do have a pterygium, it’s worthwhile remaining alert and in regular contact with your eye doctor.