Sun, wind, surf, and… a pterygium. Depending on where you live in the world, the prevalence of pterygia sits anywhere between 1% of the population to over 30%. This fleshy wing-shaped overgrowth of tissue from the whites of the eye to the cornea (the transparent dome over the colored iris) is typically dismissed as a slightly unsightly cosmetic issue for most people. As it’s also nicknamed «surfer’s eye», you can imagine how it might relate to sun, wind, and surf. In some cases, a pterygium can progress so far over the cornea that it becomes more than a slightly unsightly cosmetic issue.
What Causes Pterygia?
Pterygia (singular, pterygium) are a benign and fairly common finding among people living in sunny areas with high rates of UV radiation. Other risk factors for developing a pterygium include:
- Male gender
- Working outdoors
- Lower levels of education
- Living in rural areas
- Lower socioeconomic status
- Darker skin complexion
- Environmental irritants, such as dust and wind
- Viral infection, such as the human papilloma virus (HPV) or herpes simplex virus (HSV)
- Family genetics
It is thought that chronic UV exposure is one of the main culprits of pterygium development as it induces cellular changes to the tissues of the eye.
Can Pterygia Cause Vision Problems?
In the early stages of a small pterygium, you’re not likely to notice any issues. In fact, many people with an early pterygium don’t even realize they have a pterygium. However, as the pterygium grows, you (and unfortunately, other people), start to notice that yellowish-white triangle creeping across the cornea. Pterygia can also become red and inflamed, which not only doesn’t look great but also doesn’t feel great.
In addition to the undesirable appearance and sensation of an angry pterygium, pterygia are known to cause changes to the vision if they grow far enough. In particular, a pterygium can induce a type of vision problem called astigmatism.
Astigmatism is a form of refractive error, more commonly known as your eyeglass or contact lens prescription. Other types of refractive error including near-sightedness (myopia) and far-sightedness (hyperopia). Most cases of astigmatism arise from an irregular curvature of the cornea, which causes incoming light to be unfocused when it hits the retina at the back of the eye (hint: light needs to be focused on the retina for clear vision). Symptoms of uncorrected astigmatism can include:
- Blurry or distorted vision
- Glare sensitivity
- Seeing lights as starbursts
- Difficulty with night vision
Astigmatism can occur in anyone and at any age. However, if an eye develops a pterygium, this pterygium results in the surface of the cornea becoming irregular and subsequently developing astigmatism.
A pterygium can develop in either one or both eyes. If both eyes grow a pterygium at the same time, they can often be asymmetrical – one is larger and more progressed over the corneal surface compared to the other. In these situations, one eye might have a drastically different pterygium-related refractive error compared to the other eye. This difference in prescription between the eyes is a situation known as anisometropia.
What’s the Problem with Anisometropia?
Most people have some degree of anisometropia, though it’s more commonly within tolerable/ignorable ranges. If you wear glasses or contact lenses, you may already be aware that one eye’s prescription is a -1.50 and the other eye is a -2.25 diopter script. Some people can even have one short-sighted eye and one long-sighted eye – for example, one eye is a +0.50 and the other is -0.75 diopters.
Anisometropia can often be corrected simply by providing each eye with its correct prescription, whether in glasses or contacts. However, at some point, the degree of difference between the eyes can become a little too mind-boggling. The reason for this is because with anisometropia comes another related situation called aniseikonia.
Aniseikonia refers to the difference in size of an image seen by each eye due to unequal magnification. Near-sightedness is corrected with minus-powered lenses – minus-powered lenses cause objects to look smaller than they are, and the higher the minus power, the smaller the object is perceived. Conversely, far-sightedness is corrected using plus-powered lenses and, you guessed it, this makes objects look larger (this is why magnifying glasses are all plus-powered lenses). If you’ve ever seen someone wearing thick glasses, you can tell if they’re long-sighted or short-sighted simply by observing whether their eyes look huge through their lenses or teeny-tiny.
At about 3 diopters of aniseikonia is where the human brain begins to say nope. This can lead to symptoms including:
- Double vision (diplopia)
- Light sensitivity
Treatment for Pterygium
If a pterygium is inducing astigmatism, which is inducing anisometropia, which is inducing aniseikonia, which is inducing dizziness or any other unpleasant symptom, it’s safe to say you should probably do something about it. That something would be to have the pterygium removed with an eye surgeon.
The first-line treatment for a bothersome pterygium is surgery. Over the years there have been a variety of surgical techniques proposed for pterygium removal, mainly with the goal of minimizing the likelihood of the pterygium returning, which they have a tendency to do. If you’re slated for pterygium surgery, your surgeon will advise you of which they believe is the best surgical technique for you.
Though pterygia themselves are considered benign, they can be associated with cancerous changes so it’s still important to maintain regular eye checks. Pterygia are also linked to an increased risk of skin melanoma, so it’s a good idea to keep in touch with your dermatologist if you’ve been diagnosed with a pterygium by your optometrist or eye doctor. In the meantime, if your eyes are still clear and pterygium-free, or if your pterygium is still just a little baby, you can protect your eyes from the elements by wearing sunglasses and a hat when outdoors. Using lubricating eyedrops if you’re frequently exposed to wind and dust may also be helpful for keeping that slightly unsightly cosmetic issue at bay.
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