Pterygium develops when ultraviolet radiation damages the thin, clear tissue covering the white of your eye, triggering abnormal tissue growth that creeps from the corner of the eye toward the cornea. UV exposure is the single most important cause, but wind, dust, dry eyes, and genetics all play a role in who actually develops one. The condition is common: global estimates put the prevalence around 10% of the general population, with rates climbing sharply in sunny, equatorial regions.
UV Radiation Is the Primary Cause
Prolonged exposure to ultraviolet light is the driving force behind pterygium. UV rays damage the DNA in the cells of your conjunctiva, the transparent membrane that lines the surface of your eye. Over time, this damage can disable a key gene called p53, which normally acts as a brake on cell growth. When p53 stops working, cells begin to multiply without the usual checks, producing the fleshy, wedge-shaped tissue characteristic of pterygium. Researchers have found that pterygium cells show deletion of one copy of the p53 gene and silencing of the remaining copy, a pattern strikingly similar to what happens in UV-related skin cancers. This is why some scientists describe pterygium as a type of benign tumor rather than simple scar tissue.
UV radiation also triggers oxidative stress, which activates signaling pathways that remodel the structural tissue of the eye. These changes contribute to the fibrous, blood-vessel-rich growth that defines a pterygium.
Wind, Dust, and Dry Climates Add Up
UV light rarely acts alone. Dry weather, wind, and airborne dust particles cause repeated micro-injuries to the surface of the eye, creating conditions that make UV damage more likely to take hold. Dust exposure is significant enough that researchers have studied it as an independent risk factor. People living in arid or windy environments face a compounding effect: the same conditions that carry more particulate matter also tend to come with stronger sun exposure and faster tear evaporation.
Chemical irritants in certain work environments can contribute as well, though they are a far less common trigger than the combination of sun, wind, and dust.
Dry Eyes Lower Your Natural Defense
Your tear film is the eye’s first line of defense against UV light and environmental irritants. When that film is unstable or insufficient, the surface of the eye becomes more vulnerable. Research published in the Beyoglu Eye Journal found that tear film abnormalities may be a significant factor in pterygium development, particularly in younger patients. Even though younger people have had less cumulative UV exposure, decreased tear film stability appears to reduce protection enough to allow early pterygium formation. If you already deal with chronic dry eye, your ocular surface is essentially less shielded from the environmental factors that cause pterygium.
Who Gets It: Age, Gender, and Occupation
Pterygium becomes more common with age, which makes sense given that UV damage is cumulative. In a large Chinese population study, prevalence ranged from about 3.4% in people aged 15 to 19 up to nearly 33% in those aged 80 to 84. Men are affected slightly more often than women, likely because of greater time spent working outdoors.
Occupation is one of the strongest predictors. People who work outside, such as farmers, fishers, construction workers, and surfers, are roughly 2.5 times more likely to develop pterygium in either eye compared to indoor workers, after adjusting for age and sex. The relationship is dose-dependent: the more hours of sunlight exposure in your daily routine, the higher the risk. Living in a rural area is also an independent predictor, probably because rural work tends to involve more unprotected time in the sun.
Geography Matters: The Pterygium Belt
Pterygium prevalence tracks closely with latitude. Tropical regions near the equator consistently report higher rates, a pattern so reliable that epidemiologists refer to the band of high-prevalence zones as the “pterygium belt.” A global meta-analysis confirmed that prevalence correlates significantly with latitude but not longitude, reinforcing that UV intensity (which is strongest near the equator) is the key geographical variable. If you live or work in a low-latitude, high-sun region, your baseline risk is meaningfully higher than someone living at a northern latitude with weaker UV exposure year-round.
How Pterygium Grows and Progresses
Pterygium usually evolves very slowly. The growth is superficial, starting at the inner corner of the eye where the conjunctiva meets the cornea, and it may take years before it advances far enough to affect vision. Many people have a pterygium that never progresses beyond a cosmetic issue.
A related condition called pinguecula, a yellowish raised patch on the white of the eye, shares some of the same underlying biology. Genomic research suggests that both conditions sit on a spectrum of UV-driven tissue change, with pterygium further along the path. However, pinguecula does not show the same pre-malignant characteristics, and not every pinguecula becomes a pterygium.
Recurrence After Removal
Even after surgical removal, pterygium can grow back. Recurrence is driven by the same inflammatory and UV-related processes that caused the original growth. A retrospective study of 196 patients found that two factors most strongly predicted recurrence: the grade (size and severity) of the original pterygium, and the level of systemic inflammation measured through blood markers. Patients with higher pre-surgical inflammation were over four times more likely to see regrowth. More advanced pterygium at the time of surgery carried six times the odds of recurrence. Continued UV exposure after surgery compounds the problem, which is why protective eyewear remains important even after the growth is removed.
Reducing Your Risk
Since UV exposure is the dominant cause, eye protection is the most effective prevention. The American Academy of Ophthalmology recommends sunglasses that block 100% of UV rays, labeled as UV400 or blocking both UV-A and UV-B. Wraparound styles offer better coverage because they limit light entering from the sides. Pairing sunglasses with a broad-brimmed hat reduces exposure further. Studies show that using both together significantly lowers the likelihood of developing pterygium.
If you work outdoors, consistent use of protective eyewear during all daylight hours matters more than occasional use on especially bright days. UV damage accumulates over a lifetime, and overcast skies still transmit a substantial amount of ultraviolet radiation. For people with chronic dry eye, managing tear film stability with lubricating drops may offer an additional layer of surface protection, though this has not been studied as a standalone prevention strategy for pterygium.