Pterygium is a fleshy, wedge-shaped growth that develops on the surface of the eye and can slowly creep across the cornea. While not cancerous, this common eye condition can cause irritation, redness, and in some cases affect your vision. Understanding what causes pterygium and how to protect your eyes can help you avoid this uncomfortable condition that’s most commonly seen in people who spend a lot of time outdoors.

How Common Is Pterygium Around the World?

Pterygium affects millions of people globally, though its occurrence varies dramatically depending on where you live. The condition is most prevalent in what experts call the “pterygium belt,” which stretches between 37 degrees north and south of the equator. This geographical pattern tells us a lot about what causes the condition in the first place.

In Australia, approximately one in every 100 people develops a pterygium during their lifetime. The prevalence is particularly high among men over 60 years of age, with estimates suggesting that about 12 percent of Australian men in this age group have the condition. The numbers vary considerably across different populations and regions. Studies have found prevalence rates of 23.4 percent among the black population in Barbados, 10.1 percent in Singapore, and 30.8 percent in Japan.

In India, the condition affects between 9.5 and 13 percent of the population, with higher rates typically found in rural areas where people spend more time working outdoors. The global prevalence ranges widely from 0.3 to 29 percent, depending on the location and environmental conditions. Men are approximately twice as likely to develop pterygium compared to women, likely because they historically have spent more time working in outdoor occupations.

The condition is most commonly diagnosed in people between their 20s and 40s, though it can affect individuals of any age. Children rarely develop pterygium, which reinforces the understanding that this condition develops over years of cumulative exposure to environmental factors.

What Causes Pterygium to Develop?

The exact biological mechanism that triggers pterygium formation is not completely understood, but researchers have identified several key factors that contribute to its development. The primary culprit is long-term exposure to ultraviolet (UV) light from the sun. UV radiation appears to damage the cells on the eye’s surface, triggering an abnormal growth response in the conjunctiva, which is the clear membrane that covers the white part of your eye.

The pterygium itself is a fibrovascular overgrowth, meaning it consists of both fibrous tissue and blood vessels. It develops as an overgrowth of the conjunctiva tissue that gradually extends onto the cornea, the clear front window of your eye. The growth typically has a triangular or wing-like shape, which is actually how it got its name from the Greek words for “wing” and “fin.”

Chronic irritation from environmental conditions plays a significant supporting role. Hot, dry weather combined with wind, dust, sand, and smoke can irritate the eye surface over time. This ongoing irritation may work together with UV exposure to promote the development of pterygium. Some research also suggests that genetic factors may make certain individuals more susceptible to developing the condition.

Other possible contributing factors include vitamin A deficiency and human papilloma virus (HPV), though these connections are less clearly established. What is clear is that pterygium represents the eye’s abnormal response to long-term environmental stress, particularly from UV radiation.

Who Is Most at Risk for Developing Pterygium?

Certain groups of people face a much higher risk of developing pterygium due to their lifestyle, occupation, or geographic location. Understanding these risk factors can help you take preventive measures if you fall into a high-risk category.

People who spend extensive time outdoors without proper eye protection are at the greatest risk. This includes farmers, fishermen, sailors, gardeners, construction workers, and of course, surfers—which is why pterygium earned the nickname “surfer’s eye.” These occupations involve prolonged exposure to sunlight, often with additional exposure to wind, water, sand, or dust that can compound the irritation to the eyes. Working outdoors has been shown to increase your risk of pterygium by as much as 150 percent.

Geographic location matters significantly. People living in tropical or desert regions, particularly those close to the equator where sunlight is more intense year-round, face substantially higher risk. Coastal populations also show elevated rates, partly because sunlight reflects off water surfaces, effectively doubling UV exposure to the eyes. Even in winter or on cloudy days, UV light can reflect off various surfaces including snow, sand, water, and windows, reaching your eyes from multiple angles.

Age is another important factor. While pterygium can develop at any age, risk increases as you get older because the damage from UV exposure accumulates over your lifetime. Older adults have simply had more years of sun exposure, which increases their likelihood of developing this condition. Additionally, some people may have a genetic predisposition that makes them more susceptible to pterygium, though more research is needed to understand the hereditary aspects fully.

People who suffer from chronic dry eye conditions may also face increased risk, as the combination of dry eyes and environmental irritants can create conditions favorable for pterygium development. Similarly, individuals who have difficulty wearing contact lenses due to eye surface problems may be more vulnerable.

Recognizing the Symptoms of Pterygium

Many people first notice pterygium simply by seeing an unusual growth on their eye when they look in the mirror. The growth typically appears as a raised, fleshy, wedge-shaped area that may look pinkish or whitish. You can usually see blood vessels running through it, giving it a slightly red appearance. The pterygium most commonly starts in the inner corner of the eye, nearest to your nose, though it can occasionally develop on the outer corner or even on both sides of the eye at the same time.

In its early stages, pterygium may not cause any noticeable symptoms beyond its appearance. However, as it grows or becomes inflamed, you may experience a range of uncomfortable sensations. A very common symptom is the feeling that something is stuck in your eye, even though nothing is actually there. This foreign body sensation can be quite bothersome and persistent.

Other symptoms include redness or a bloodshot appearance in the affected eye, which can come and go or remain constant. Your eye may feel dry, gritty, or irritated, similar to the sensation of dry eye. Paradoxically, some people experience excessive tearing or watery eyes as the eye tries to compensate for the irritation. Itching and burning sensations are also common, and some people experience actual eye pain, though this is less frequent.

As pterygium grows larger and extends further onto the cornea, it can begin to affect your vision. You might notice blurred vision or even double vision in rare cases. The growth can also cause astigmatism, which is an irregular curvature of the cornea that distorts vision. If you wear contact lenses, you may find them increasingly uncomfortable or difficult to wear as the pterygium grows.

The severity of symptoms varies considerably from person to person. Some pterygia remain small and stable for years, causing minimal or no discomfort. Others grow more aggressively and cause significant irritation. The growth may also become intermittently inflamed, causing periods of increased redness and discomfort followed by calmer periods.

How to Prevent Pterygium from Developing

Prevention is far more effective than treatment when it comes to pterygium. The good news is that protecting yourself from this condition involves straightforward steps that also benefit your overall eye health and reduce your risk of other sun-related eye problems.

The single most important preventive measure is protecting your eyes from UV light. This means wearing sunglasses that block 100 percent of both UVA and UVB rays whenever you’re outdoors. Look for sunglasses labeled as providing “100% UV protection,” “UV 400,” or with an Eye Protection Factor (EPF) rating of 9 or 10. Not all sunglasses provide adequate UV protection, so checking the label is essential—darker lenses don’t necessarily mean better UV protection.

The style of sunglasses matters too. Wrap-around or close-fitting frames offer superior protection compared to smaller frames because they prevent UV light from entering around the edges of the lenses. This is particularly important because sunlight can reach your eyes from the sides, top, and bottom of regular glasses, partially defeating their protective purpose.

Wearing a wide-brimmed hat provides additional protection by blocking overhead sunlight. The combination of UV-protective sunglasses and a hat offers the best defense against the damaging effects of UV radiation. This protection is important year-round, not just during summer, because UV light can be intense even on cloudy days and during winter, especially in areas with snow that reflects sunlight.

Starting sun protection at a young age is crucial because UV damage accumulates over a lifetime. Parents should encourage children to wear sunglasses and hats when playing outdoors, and infants in strollers should have awnings or hoods to protect them from direct sunlight. Building these habits early helps prevent not only pterygium but also other sun-related eye conditions later in life.

Minimizing exposure to other environmental irritants also helps. If possible, avoid spending time in very dusty, windy, or smoky conditions. If your occupation requires working in these conditions, protective eyewear designed for your specific environment can help shield your eyes. Keeping your eyes well-lubricated with artificial tears can also help, especially if you work in dry or dusty environments or suffer from dry eye symptoms.

Common Symptoms That Should Prompt Medical Attention

While pterygium often starts as a minor cosmetic concern, certain symptoms signal that you should seek medical evaluation. Knowing when to see an eye care professional can help prevent complications and protect your vision.

If you notice any new growth on your eye, it’s worth having it examined. While pterygia are benign, other conditions can sometimes look similar, and only a qualified eye care provider can make an accurate diagnosis. A raised, fleshy, triangular growth with visible blood vessels that starts at the inner corner of your eye and extends toward the colored part is the typical presentation of pterygium.

Increasing size is an important warning sign. If you notice that the growth is extending further across your eye over time, you should have it evaluated. Your eye doctor will measure the pterygium from the edge of the cornea to its furthest point and record this measurement so they can track whether it’s growing at future appointments. Significant growth toward the center of your cornea requires closer monitoring because it could eventually interfere with your vision.

Vision changes of any kind warrant immediate attention. Blurred vision, double vision, or distorted vision could indicate that the pterygium is affecting your cornea enough to interfere with how light enters your eye. Even if these changes seem minor at first, they suggest that the pterygium is at a stage where intervention might be necessary.

Persistent or worsening symptoms like severe redness, pain, significant irritation, or constant foreign body sensation suggest that the pterygium has become inflamed and may need treatment. While mild intermittent symptoms can often be managed with simple measures, symptoms that don’t improve or that interfere with your daily activities should be evaluated by an eye care professional.

How Pterygium Changes Normal Eye Function

Understanding what happens to your eye when a pterygium develops helps explain why this condition causes the symptoms it does. The changes occur gradually, starting at the microscopic level and eventually becoming visible to the naked eye.

Pterygium represents an abnormal proliferation of conjunctival tissue. Normally, the conjunctiva is a thin, transparent membrane that covers the white part of your eye and lines the inside of your eyelids. It contains tiny blood vessels and helps keep the eye surface moist and protected. When a pterygium develops, this tissue begins growing in an uncontrolled manner, becoming thicker and more vascular than normal.

The growth extends from the conjunctiva onto the cornea, which is normally completely clear and smooth. As the pterygium advances across the cornea, it brings blood vessels with it. These vessels are visible as the reddish lines you can see in the fleshy growth. The presence of this tissue and its blood vessels on the cornea is abnormal and can interfere with the cornea’s optical clarity.

The pterygium also distorts the normal smooth curvature of the cornea. Your cornea needs to maintain a precise, regular curve to focus light properly onto your retina. When pterygium pulls on the corneal surface or grows across it, it creates irregularities in this curve, resulting in astigmatism. This irregular shape causes light to focus unevenly, creating the blurred or distorted vision that many people with larger pterygia experience.

The growth can also affect your eye’s tear film—the thin layer of moisture that normally covers and protects your eye surface. Pterygium may disrupt the normal distribution of tears, leading to dry spots or excessive tearing as your eye tries to compensate. This disruption explains the dry, gritty sensation many people experience, as well as the paradoxical symptom of watery eyes.

In advanced cases where the pterygium grows large enough, it can restrict eye movement. The growth may create a physical tether between the conjunctiva and cornea that limits how freely your eye can move in certain directions. This restriction is unusual but can occur when pterygia are left untreated for many years and grow quite large. In extreme cases, if a pterygium grows far enough across the cornea to cover the pupil, it can directly block light from entering the eye, significantly impairing vision.