Skip to content
How It Works
Explore
Ask a Question Resources Pricing
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Sign Up
PubMed This is a summary of 22 peer-reviewed journal articles Updated
Ophthalmology

Understanding Pterygium: Causes and Biology

At a Glance

Pterygium is a noncancerous growth on the eye most strongly linked to repeated ultraviolet exposure. Wind, dust, dryness, and inflammation can contribute, while UV-blocking sunglasses, a hat, and artificial tears help reduce irritation but do not cure an existing growth.

Pterygium (pronounced tur-IJ-ee-um) is a common, non-cancerous growth on the surface of the eye [1]. While it is sometimes called “surfer’s eye,” you do not have to be a surfer to develop one. It is a fibrovascular growth, meaning it is composed of both fibrous tissue and blood vessels, that typically begins in the corner of the eye (the conjunctiva) and slowly stretches toward the center [1][2].

Because it is often wedge-shaped or triangular, it can look like a small piece of flesh or a film creeping over the cornea (the clear front window of the eye) [1]. While the growth itself is not a tumor, it is active tissue that can extend across the surface and, if left unchecked, can eventually interfere with your vision by changing the shape of the eye or blocking your line of sight [1][3].

Who is Most at Risk?

Pterygium is found all over the world. A recent model estimated it affects about 8% of the global population, or roughly 553 million people, though estimates vary depending on the region and the way they are measured [1]. It is much more common in certain groups and environments.

  • The Equatorial Belt: People living in tropical and subtropical regions near the equator have the highest rates because the sun’s ultraviolet rays are most intense there [1][4].
  • Outdoor Workers and Enthusiasts: Farmers, construction workers, sailors, and surfers are at higher risk due to long-term exposure to the elements [5][6].
  • Age and Sex: The condition becomes more common as people get older [1]. While some older studies suggested men were more affected, recent data shows that men and women are affected at nearly equal rates when they have similar levels of sun exposure [1][5].
  • Genetics: While environmental factors are the main cause, some people may have a genetic predisposition that makes their eye tissue more sensitive to damage [3][7].

How the Environment Changes the Eye

A pterygium does not appear overnight. It is the result of long-term cellular changes triggered by your environment. The biological process involves several interacting mechanisms that lead to tissue thickening and new blood vessel formation.

Ultraviolet (UV) Radiation

UV light, specifically UVA and UVB rays, is the primary driver of pterygium [8][9]. When these rays hit the eye over many years, they damage the limbal cells [10]. These cells live at the limbus—the border between the white of the eye and the clear cornea—and their job is to act as a barrier and maintain the clear surface of the cornea [11].

When UV light damages these cells, they can become dysfunctional [12]. This dysfunction allows the neighboring conjunctival tissue to migrate across the border and onto the clear cornea [11][13].

Oxidative Stress and Inflammation

The sun’s energy also creates reactive oxygen species in the eye tissue, leading to oxidative stress [3][14]. This stress, combined with chronic inflammation, can alter how the cells regulate their own growth, contributing to the tissue’s slow expansion [15][16].

Wind, Dust, and Dryness

Wind and dust also contribute by acting as chronic irritants. Constant exposure to wind can dry out the tear film that protects your eye [17]. This dryness and mechanical irritation lead to inflammation, which prompts the release of growth factors like VEGF (Vascular Endothelial Growth Factor) [18]. VEGF signals the body to grow new blood vessels into the tissue, giving the pterygium its characteristic red, fleshy appearance [19].

How to Protect Your Eyes

While you cannot change your genetics or your age, you can significantly reduce the environmental stressors that cause irritation and may contribute to progression. Protection reduces exposure and improves comfort, though it does not reliably shrink or cure an existing pterygium.

  • Wear UV400 Sunglasses: Look for glasses that block 99% to 100% of both UVA and UVB rays [20]. Wraparound styles are best because they prevent UV rays and wind from entering from the sides [5]. Note that while UV-blocking contact lenses offer some protection, they do not replace the need for physical sunglasses.
  • Use a Wide-Brimmed Hat: A hat can block a significant portion of the sun that hits your eyes from above [2][21].
  • Manage Dryness: Using preservative-free artificial tears can help keep the eye surface lubricated, reducing the chronic irritation caused by wind and dust [22].
  • Protect Your Eyes on the Water: Because water reflects UV rays upward, surfers and swimmers should consider specialized UV-protective goggles or eyewear [6].

Common questions in this guide

What is pterygium, and is it cancerous?
Pterygium is a noncancerous, wedge-shaped growth on the surface of the eye. It usually starts on the conjunctiva, the tissue over the white of the eye, and may extend onto the cornea. A larger growth can change the cornea’s shape or interfere with vision.
What causes pterygium to form?
Repeated ultraviolet, or UV, exposure is the main cause described for pterygium. Wind, dust, dryness, and long-term inflammation can also irritate the eye surface and support tissue growth, while age and genetic susceptibility may contribute.
Who is most likely to develop pterygium?
Risk is higher for people who live in tropical or subtropical regions, especially near the equator, and for people who spend a lot of time outdoors. Outdoor work or hobbies, including farming, construction, sailing, and surfing, increase exposure to sunlight, wind, and dust. Older age and possible genetic susceptibility may also play a role.
How can I protect my eyes if I have or want to prevent pterygium?
Wear sunglasses that block 99% to 100% of UVA and UVB rays, preferably in a wraparound style, and use a wide-brimmed hat. Preservative-free artificial tears can reduce dryness, and UV-protective goggles may help around reflective water. These measures reduce exposure and irritation but do not reliably shrink or cure an existing pterygium.
Can pterygium affect vision?
Yes. If it grows toward the center of the cornea, pterygium can block part of the line of sight or alter the cornea’s shape, which may affect vision. An eye-care professional can assess the growth’s size, location, and effect on the cornea.
How do I know whether my pterygium is active or needs monitoring?
An eye-care professional can look for changes in the growth, redness, irritation, dryness, and signs that it is affecting the cornea or vision. This examination can help determine whether the pterygium appears quiet or active and how often it should be monitored.

Get notified when new evidence is published on pterygium.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.

References

References (22)
  1. 1

    Global, regional, and national prevalence of pterygium in 2023: a systematic review and modelling analysis.

    Shan S, Wu J, Liu X, et al.

    Journal of global health 2026; (16()):04271 doi:10.7189/jogh.16.04271.

    PMID: 42466630
  2. 2

    Ethnic Variations in Pterygium in a Rural Population in Southwestern China: The Yunnan Minority Eye Studies.

    Zhong H, Chen Q, Li J, et al.

    Ophthalmic epidemiology 2016; (23(2)):116-21 doi:10.3109/09286586.2015.1099685.

    PMID: 26950531
  3. 3

    The Role of the Stromal Extracellular Matrix in the Development of Pterygium Pathology: An Update.

    Martín-López J, Pérez-Rico C, Benito-Martínez S, et al.

    Journal of clinical medicine 2021; (10(24)) doi:10.3390/jcm10245930.

    PMID: 34945227
  4. 4

    Occupational Exposure to Solar Radiation at Different Latitudes and Pterygium: A Systematic Review of the Last 10 Years of Scientific Literature.

    Modenese A, Gobba F

    International journal of environmental research and public health 2017; (15(1)) doi:10.3390/ijerph15010037.

    PMID: 29278403
  5. 5

    Prevalence and risk factors of pterygium: a systematic review and meta-analysis.

    Rezvan F, Khabazkhoob M, Hooshmand E, et al.

    Survey of ophthalmology 2018; (63(5)):719-735 doi:10.1016/j.survophthal.2018.03.001.

    PMID: 29551597
  6. 6

    Prevalence of Pterygia in Hawaii: Examining Cumulative Surfing Hours as a Risk Factor.

    Lin AD, Miles K, Brinks MV

    Ophthalmic epidemiology 2016; (23(4)):264-8 doi:10.3109/09286586.2015.1119284.

    PMID: 26953498
  7. 7

    A novel role for CRIM1 in the corneal response to UV and pterygium development.

    Maurizi E, Schiroli D, Atkinson SD, et al.

    Experimental eye research 2019; (179()):75-92 doi:10.1016/j.exer.2018.10.012.

    PMID: 30365943
  8. 8

    What is truly evidence-based in pterygium? An umbrella review of systematic reviews and meta-analyses.

    Kaplan Moscovici B, Rodrigues PF, Correa Dantas PE, Felberg S

    The ocular surface 2026; (41()):203-214 doi:10.1016/j.jtos.2026.06.004.

    PMID: 42276419
  9. 9

    Pterygium: an update on pathophysiology, clinical features, and management.

    Shahraki T, Arabi A, Feizi S

    Therapeutic advances in ophthalmology 2021; (13()):25158414211020152 doi:10.1177/25158414211020152.

    PMID: 34104871
  10. 10

    UV light-blocking contact lenses protect against short-term UVB-induced limbal stem cell niche damage and inflammation.

    Notara M, Behboudifard S, Kluth MA, et al.

    Scientific reports 2018; (8(1)):12564 doi:10.1038/s41598-018-30021-8.

    PMID: 30135547
  11. 11

    Reconsidering pterygium in the context of focal limbal stem cell dysfunction.

    Gurdal M, Tutas Gunaydin N, Barut Selver O

    Clinical & experimental optometry 2026; 1-5 doi:10.1080/08164622.2026.2708026.

    PMID: 42521296
  12. 12

    Short-term uvb-irradiation leads to putative limbal stem cell damage and niche cell-mediated upregulation of macrophage recruiting cytokines.

    Notara M, Refaian N, Braun G, et al.

    Stem cell research 2015; (15(3)):643-654 doi:10.1016/j.scr.2015.10.008.

    PMID: 26520427
  13. 13

    Consecutive dosing of UVB irradiation induces loss of ABCB5 expression and activation of EMT and fibrosis proteins in limbal epithelial cells similar to pterygium epithelium.

    Domdey M, Kluth MA, Maßlo C, et al.

    Stem cell research 2022; (64()):102936 doi:10.1016/j.scr.2022.102936.

    PMID: 36242878
  14. 14

    HMGB1 in the pathogenesis of ultraviolet-induced ocular surface inflammation.

    Han SJ, Min HJ, Yoon SC, et al.

    Cell death & disease 2015; (6()):e1863 doi:10.1038/cddis.2015.199.

    PMID: 26313914
  15. 15

    p53 inhibition by MDM2 in human pterygium.

    Cao D, Ng TK, Yip YWY, et al.

    Experimental eye research 2018; (175()):142-147 doi:10.1016/j.exer.2018.06.021.

    PMID: 29932882
  16. 16

    MicroRNA regulation of MDM2-p53 loop in pterygium.

    Teng Y, Yam GH, Li N, et al.

    Experimental eye research 2018; (169()):149-156 doi:10.1016/j.exer.2018.01.015.

    PMID: 29360447
  17. 17

    Prevalence and Associated Factors of Pterygium Among Adults Living in Kolla Diba Town, Northwest Ethiopia.

    Kassie Alemayehu T, Addis Y, Yenegeta Bizuneh Z, et al.

    Clinical ophthalmology (Auckland, N.Z.) 2020; (14()):245-255 doi:10.2147/OPTH.S239982.

    PMID: 32099312
  18. 18

    Single-cell RNA sequencing reveals the complex cellular niche of pterygium.

    Zhang X, Han P, Qiu J, et al.

    The ocular surface 2024; (32()):91-103 doi:10.1016/j.jtos.2024.01.013.

    PMID: 38290663
  19. 19

    Unravelling the molecular tapestry of pterygium: insights into genes for diagnostic and therapeutic innovations.

    Gupta M, Arya S, Agrawal P, et al.

    Eye (London, England) 2024; (38(15)):2880-2887 doi:10.1038/s41433-024-03186-y.

    PMID: 38907016
  20. 20

    [Alterations of the anterior segment of the eye caused by exposure to UV radiation].

    Hampel U, Elflein HM, Kakkassery V, et al.

    Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft 2022; (119(3)):234-239 doi:10.1007/s00347-021-01531-0.

    PMID: 34860283
  21. 21

    Prevalence and associated factors of pterygium among adults living in Gondar city, Northwest Ethiopia.

    Anbesse DH, Kassa T, Kefyalew B, et al.

    PloS one 2017; (12(3)):e0174450 doi:10.1371/journal.pone.0174450.

    PMID: 28358813
  22. 22

    Systematic Review: Effects of Pterygium and Pingueculum on the Ocular Surface and Efficacy of Surgical Excision.

    Linaburg T, Choi D, Bunya VY, et al.

    Cornea 2021; (40(2)):258-267 doi:10.1097/ICO.0000000000002575.

    PMID: 33156079

This page is for informational purposes only and does not constitute medical advice; it explains how UV exposure and environmental irritation may contribute to pterygium. An eye-care professional should assess your growth, vision, and need for monitoring or treatment.