Pterygium: when to watch it and when surgery is considered

A pterygium does not always need surgery, and early ones often cause no symptoms. Surgery is considered when the growth threatens or blurs vision, keeps the eye irritated, distorts the cornea, or looks unusual enough to need a firm diagnosis.

What a pterygium is

A pterygium is a fleshy, wing-shaped growth of the conjunctiva (the clear skin over the white of the eye) that crosses onto the cornea. It can cause irritation, dryness and a gritty feeling, and in some people it grows far enough to affect sight [1].

Ultraviolet light is thought to be the main driver [1]. A pooled analysis of 68 studies and 415,911 people put the worldwide prevalence at about 12%, rising with age. Outdoor work was linked with higher odds of pterygium, and wearing sunglasses with lower odds [2]. An older case-control study of 278 patients in Brisbane also found that regular glasses, sunglasses or a hat were associated with lower risk [3]. These studies show a link with developing a pterygium. They do not prove that sun protection shrinks one that is already there.

What we check while watching it

Size and position. Early pterygia are usually symptom-free. Vision becomes affected as the growth moves toward the centre of the cornea [4]. We measure and photograph the growth so that change can be seen from one visit to the next.

Corneal shape. A pterygium is linked with astigmatism. In a study of 30 eyes, larger pterygia went with more astigmatism and poorer unaided vision [5]. The optometrists at Rose Optometry use a Heidelberg ANTERION, a swept-source OCT instrument, for corneal imaging. Its corneal curvature measurements were repeatable in a study of 101 eyes [7]. We track this over time alongside your glasses prescription.

Whether it looks typical. A small number of growths that look like pterygia turn out to contain early surface cancer cells, called ocular surface squamous neoplasia (OSSN). A meta-analysis of 12 studies and 8,688 removed pterygia found OSSN in a pooled 1.32%. The rate was higher in regions with more ultraviolet exposure, the regional estimate for Oceania was 8.57%, and the evidence was graded low to very low certainty. Age, sex and position of the growth did not separate the two conditions [8].

Anterior segment OCT can help. In reviews and small studies, OSSN showed a thickened, bright surface layer with an abrupt edge, while a pterygium showed a surface layer of near-normal thickness over a wedge of deeper tissue [9][10]. In one study of 40 patients, a surface-layer thickness cut-off separated the two with 100% sensitivity and 94.7% specificity [10]. These studies were small and their cut-offs differed, so a scan supports a referral decision and does not replace laboratory testing of removed tissue. A review advises treating atypical pterygia with more suspicion [11].

When surgery is considered

Our optometry team would usually discuss referral when:

• the growth is approaching the line of sight [4]
• astigmatism is increasing. A review notes this can be a reason for earlier removal, although how much astigmatism surgery will reverse is hard to predict and has to be weighed against the risk of regrowth [11]
• irritation or redness persists despite other measures, though one review describes surgery for this reason alone as still open to debate [1][11]
• the appearance is atypical [8][11]
• you are being measured for cataract surgery. In 60 eyes that had pterygium and cataract surgery together, the result was more short-sighted than planned, and more so with larger pterygia [12].

Surgery is the only treatment that removes a pterygium, and regrowth is the main drawback [1]. Technique matters. When the growth is simply cut out and the area left bare, reported regrowth has been as high as 80%. Covering the area with a graft lowers that risk. A Cochrane review of 20 trials (1,947 eyes) found that a graft of the patient's own conjunctiva had less regrowth at six months than a donor amniotic membrane graft, with evidence rated low to moderate quality [1]. The difference was clearest in people whose pterygium had already come back once. In first-time pterygia alone it was not statistically significant [1]. Dr James McKelvie's clinic describes its approach on its page about pterygium surgery at Eye Surgeons NZ.

What we check after surgery

Regrowth. In recent series using the patient's own conjunctiva as the graft, regrowth was reported in 5.2% of 310 patients followed for at least a year [13] and 13.2% of 91 patients followed for a median of about six and a half months in a high-ultraviolet setting, a figure the authors say may underestimate the true rate [14]. When regrowth happens it tends to be early. One study reported an average of 4.4 months, but its average follow-up was only about 5 to 7 months, so later regrowth would have been missed [15]. In another, 12 of 15 recurrences appeared within 12 months [16]. Checks through the first year are aimed at that window.

Vision and glasses. In the 30-eye study, astigmatism fell by an average of 2.00 dioptres after surgery, and corneal shape was stable by two months, which the authors suggest as the point for new glasses [5].

Cataract planning. If cataract surgery is likely, tell your surgeon about the pterygium so the order and timing of measurements can be planned [12].

If you live in Hamilton or the wider Waikato, the optometrists at Rose Optometry at 37 Lake Road, Frankton can photograph, scan and monitor a pterygium and arrange referral when it is needed.

Choosing a surgeon: in Hamilton, pterygium surgery is offered by Dr James McKelvie and his colleagues at Eye Surgeons NZ, and by the surgeons at Hamilton Eye Clinic and Eye Institute, and Mr Chris Murphy. You are free to choose any of them, or another surgeon, and we will send your results to whoever you choose.

This article is general information and does not replace an eye examination.

Care at Rose Optometry is provided by our optometrist team: Jagrut Lallu, Jacqueline Rowe, Emilie Lawson, Jason Shen, Jessica Wood, Stella Wong and Anjali Hira.

References

1. Clearfield, 2016, Cochrane Database Syst Rev. DOI PubMed 26867004
2. Rezvan, 2018, Surv Ophthalmol. DOI PubMed 29551597
3. Mackenzie, 1992, Ophthalmology. DOI PubMed 1495784
4. Malozhen, 2017, Vestn Oftalmol. DOI PubMed 29165417
5. Gumber, 2021, Indian J Ophthalmol. DOI PubMed 34427231
7. Cheng, 2022, Graefes Arch Clin Exp Ophthalmol. DOI PubMed 35171331
8. Mihalache, 2026, Br J Ophthalmol. DOI PubMed 41167795
9. Gündüz, 2023, Eye (Lond). DOI PubMed 36513855
10. Başkan, 2023, Cureus. DOI PubMed 36941905
11. Shahraki, 2021, Ther Adv Ophthalmol. DOI PubMed 34104871
12. Kamiya, 2015, Medicine (Baltimore). DOI PubMed 26717362
13. Aidenloo, 2018, Jpn J Ophthalmol. DOI PubMed 29549462
14. Pardo-Bayona, 2026, BMC Ophthalmol. DOI PubMed 42143290
15. Campagna, 2018, Cornea. DOI PubMed 29176451
16. Kusano, 2024, Cornea. DOI PubMed 37948044

This article is general information, not personal medical advice. Most sources were checked against the full published papers in October 2026.