A pterygium is a benign growth on the eye’s surface that most people notice as a fleshy pink-white triangle creeping in from the corner. Small ones rarely cause trouble. Once they start affecting your cornea, that changes.
A pterygium (the plural is pterygia) is an abnormal growth of conjunctival tissue that spreads from the white of the eye onto the clear cornea. It almost always starts at the nasal side, moving toward the centre of the eye. The condition is benign – it is not a tumor, it will not spread to other parts of the body – but it can cause persistent redness, irritation, and over time, significant distortion of the cornea that affects vision. UV light is the main driver. People who spend a lot of time outdoors, particularly in sunny, dusty, or windy environments, are far more likely to develop one than people who don’t.
What You Need to Know About Pterygium
- A pterygium grows from the conjunctiva onto the cornea and can affect vision if it reaches the visual axis or causes significant astigmatism
- UV exposure is the primary cause – it is sometimes called “surfer’s eye” for good reason
- Small pterygia that don’t threaten vision are managed conservatively with lubricating drops and UV protection
- Surgery is indicated when vision is affected, astigmatism worsens, the growth approaches the pupil, or symptoms are intolerable
- Recurrence after surgery is common – rates are much lower with conjunctival autograft than with older bare-sclera excision techniques
- A related but distinct lesion, the pinguecula, is a similar yellowish deposit that does not grow onto the cornea
What Causes a Pterygium?
UV radiation is central. Chronic exposure to ultraviolet light, particularly UV-B, causes changes in the limbal stem cells – the stem cells that sit at the junction between the cornea and conjunctiva. Over years, this leads to abnormal conjunctival proliferation that extends across the corneal surface. The pattern of distribution globally matches UV exposure almost exactly: the condition is far more prevalent in populations living within 40 degrees of the equator.
Dry, dusty, and windy environments compound the risk. Outdoor workers – farmers, fishermen, construction workers – and people who spend significant time outdoors without adequate eye protection have substantially higher rates. The name “surfer’s eye” comes from the combination of UV exposure and the dry, wind-exposed environment surfers spend time in, though the condition is far more widespread than that group.
Age plays a role too. Pterygia typically appear in adults over 30, reflecting the cumulative nature of UV damage. There is a genetic predisposition in some families. Dry eye disease frequently coexists and can make symptoms worse – the unstable tear film irritates the pterygium and vice versa.
Symptoms
Many people discover a pterygium when they notice a visible growth in the mirror, or when someone comments on the appearance of their eye. Symptoms when present include:
- Persistent redness, particularly at the medial corner of the eye
- A sensation of grittiness or a foreign body
- Dryness and irritation, often worse in wind or air conditioning
- Blurred vision, particularly if the growth distorts the corneal surface
- Induced astigmatism causing progressive blurring or doubling of images
- Occasional tearing or light sensitivity during active growth phases
The growth is usually slow but not always predictable. Some pterygia remain stable for years; others progress steadily. Periods of rapid growth can occur, particularly after UV exposure or in dry, irritating conditions. Pain is not typical – if an eye with a pterygium becomes acutely painful, something else is going on.
Diagnosis and Monitoring
Diagnosis is clinical – a slit-lamp examination is all that is needed. The ophthalmologist will measure how far the growth extends onto the cornea, assess the quality of the corneal surface, and check for induced astigmatism. Corneal anterior segment imaging including topography is useful when significant astigmatism is suspected, providing a detailed map of corneal curvature changes caused by the pterygium’s pull.
Monitoring matters. A pterygium that is small and stable today might be approaching the visual axis in two years. Most ophthalmologists recommend annual review for established pterygia, with more frequent monitoring if growth appears to be active.
Treatment
Lubricating drops and UV protection
For a small, stable pterygium that isn’t affecting vision, conservative management is entirely appropriate. Preservative-free lubricating drops reduce irritation and dryness. Wearing UV-blocking wraparound sunglasses outdoors is the most important thing a patient can do to slow progression and reduce the likelihood of recurrence after surgery. Mild inflammation can be managed with short courses of topical anti-inflammatory drops, but these are not a long-term solution.
Conjunctival autograft – the current standard
Surgery is performed when the pterygium is encroaching on the visual axis, causing visually significant astigmatism, producing intolerable symptoms, or continuing to grow. The pterygium is excised and the bare area is covered with a graft of healthy conjunctiva taken from the upper part of the same eye. This conjunctival autograft technique has substantially lower recurrence rates than the older bare-sclera method, where the sclera was simply left exposed after excision. Mitomycin C, an antiproliferative agent, is sometimes applied during surgery to further reduce recurrence risk. The procedure is typically done under local anaesthesia as a day case.
UV protection is not optional
Recurrence is the main concern after pterygium surgery. Even with autograft, 5–10% recur, and recurrent pterygia are more aggressive and harder to treat than primary ones. The most important thing a patient can do postoperatively is consistent UV protection – good quality sunglasses worn regularly, especially outdoors. Steroid drops in the postoperative period reduce inflammation and recurrence risk.
Pterygium and Dry Eye: An Uncomfortable Combination
Pterygium and dry eye disease frequently occur together and each makes the other worse. The pterygium disrupts the smooth corneal surface that a stable tear film depends on, while dry eye irritation promotes inflammation and may stimulate pterygium growth. Managing both simultaneously produces better outcomes than treating only the visible lesion.
Patients with significant dry eye should have this addressed before pterygium surgery – dry eye increases surgical discomfort, slows healing, and may contribute to recurrence. Similarly, after surgical removal, dry eye symptoms often improve as the smooth corneal surface is restored. The overlap with cornea and refractive surgery specialists is considerable here, particularly when the pterygium has induced significant corneal changes.
See Your Ophthalmologist If You Notice
- A change in vision – blurring or distortion that is new or worsening
- Rapid growth of a known pterygium over weeks to months
- Significant redness and discomfort that doesn’t respond to lubricating drops
- The growth appearing to cross the pupil margin
- Any pigmented lesion on the conjunctiva – pterygia are not pigmented, and any dark lesion needs prompt assessment to exclude conjunctival melanoma
Frequently Asked Questions About Pterygium
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Does a pterygium always need surgery?
No. Most small pterygia are managed conservatively for years or indefinitely. Surgery is reserved for pterygia that are growing toward the visual axis, causing significant astigmatism, or producing symptoms that affect daily life. Having a pterygium doesn’t automatically mean you need an operation – but it does mean you should have it monitored regularly.
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Will it grow back after surgery?
It can. With the modern conjunctival autograft technique, recurrence rates are around 5–10%. Recurrent pterygia tend to be more aggressive than the original. Consistent UV protection postoperatively is the single most important factor in reducing recurrence. Patients who go back to working outdoors without adequate eye protection have much higher rates.
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Can a pterygium make you go blind?
Not in the way most people mean. A pterygium can cause significant visual impairment if it grows to cover the pupil or induces severe corneal astigmatism, but these situations are addressed by surgery. The key is not letting it reach that stage. Regular monitoring and timely surgery when indicated prevent serious visual loss.
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Is a pterygium the same as a cataract?
No – completely different. A cataract is a clouding of the lens inside the eye. A pterygium is a surface growth on the white of the eye extending onto the cornea. They can coexist in the same patient but are unrelated conditions requiring different treatments.
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How do I stop my pterygium from growing?
UV protection is the primary tool. Wraparound sunglasses with UV-blocking lenses worn consistently outdoors, a hat with a brim, avoiding prolonged exposure to wind, dust, and dry environments. Keeping dry eye under control with lubricating drops also helps by reducing the chronic irritation that can stimulate growth. There’s no medication that stops a pterygium from growing – protection and monitoring are what matter.
The American Academy of Ophthalmology’s pterygium page gives a clear patient overview of the condition and its treatment options. For detailed surgical outcome data, the published literature on conjunctival autograft techniques gives a thorough account of why autograft has become the standard of care. Our cornea and refractive surgery section covers the broader range of conditions affecting the front of the eye.
A pterygium is a fibrovascular growth of conjunctival tissue that invades the cornea from the limbus, typically nasally, in a triangular or wing-shaped configuration. It is not a simple degenerative process , it is an active fibrovascular proliferation driven by UV-B-induced limbal stem cell dysfunction, with features that parallel low-grade neoplasia: angiogenesis, matrix metalloproteinase upregulation, and p53 gene mutations in the epithelium. Prevalence is highest in populations living between 30°N and 30°S latitude (the “pterygium belt”), reaching 20-30% in some tropical coastal populations. UV-B exposure is the primary environmental driver. Management ranges from observation and lubricants for small asymptomatic pterygia to surgical excision with conjunctival autograft for progressive, symptomatic, or visually threatening lesions. The recurrence rate after bare sclera excision historically exceeded 50%; modern conjunctival autograft techniques have reduced this to below 5-10%.
Clinical Overview: Pterygium
- Classification: Graded by corneal extension: T1 (atrophic , corneal vessels visible through pterygium body, thin); T2 (intermediate); T3 (fleshy , opaque, obscures underlying vessels). Pterygium type predicts recurrence risk: T3 has highest recurrence. Nasal location: 90-95%. Temporal: 5-10%. Bilateral: 20-30%.
- Indications for surgery: Approaching visual axis (within 1-2 mm of pupil margin), significant induced corneal astigmatism (>1-2 D), contact lens intolerance from altered corneal surface, persistent symptoms despite lubricants (redness, irritation, foreign body sensation, cosmetic concern), rapid progression documented over 6-12 months
- Preferred surgical technique: Excision with conjunctival autograft (CAG) , harvested from superior bulbar conjunctiva and sutured or glued to the bare sclera. Recurrence below 5-10% with glue fixation. Amniotic membrane transplantation (AMT) as alternative when conjunctival tissue is scarce or patient has dry eye.
- Adjunctive mitomycin C (MMC): 0.02-0.04% applied intraoperatively for 1-5 minutes to bare sclera after pterygium excision. Reduces recurrence , most benefit in recurrent pterygia or high-risk cases. Risk: scleral necrosis, wound dehiscence, long-term ocular surface toxicity if used excessively.
- Prevention: UV-blocking sunglasses (wraparound preferred), wide-brimmed hat, reduce outdoor midday UV exposure. Lubricant drops for ocular surface irritation reduce the inflammatory stimulus. No pharmacological prevention beyond UV avoidance.
- Recurrence: Defined as fibrovascular tissue re-growing onto the corneal surface post-excision. Most recurrences appear within 6 months of surgery. Young age, T3 morphology, equatorial latitude, bare sclera technique, and inadequate conjunctival graft are risk factors.
Pathophysiology
Pterygium arises from the limbal stem cell niche , the anatomical boundary between the corneal and conjunctival epithelium. Chronic UV-B exposure (wavelength 290-320 nm) causes DNA damage in limbal basal cells, activating oncogenic pathways including p53 mutations, upregulation of MMP-1, MMP-3, and MMP-13, and increased expression of VEGF and TGF-beta. Limbal stem cells lose their normal barrier function and are replaced by conjunctival epithelial cells that migrate centripetally over the corneal surface.
The fibrovascular head of the pterygium consists of degenerative subepithelial elastic tissue (elastoid material , not true elastic fibers, but UV-denatured collagen), fibroblasts, inflammatory cells, and abnormal vasculature. The subepithelial layer contains Bowman’s layer destruction at the pterygium advancing edge, which is the mechanism of astigmatism induction. The vascular component explains the redness and the angiogenic features that parallel neoplastic behavior.
Stocker’s line: An iron deposition line in the corneal epithelium ahead of the advancing pterygium head , similar in mechanism to the Fleischer ring in keratoconus. A Stocker’s line indicates slower growth (the epithelium has had time to accumulate iron deposits at the pterygium edge). Its presence is a mildly favorable prognostic indicator.
Clinical Assessment
Determining extent and progression: Document the pterygium morphology (T1-T3 Tan grading), the distance of the head from the visual axis in millimeters, the induced corneal astigmatism on topography, and BCVA (best-corrected visual acuity) with current spectacle correction (visual acuity testing). Compare to previous measurements , a pterygium that has advanced more than 1 mm toward the visual axis over 12 months, or induced more than 1 D additional astigmatism, is considered progressive and warrants discussion of surgery.
Corneal topography: With-the-rule astigmatism (steepening at the 90° meridian, flattening at 180°) is the most common astigmatism pattern from a nasal pterygium. Large pterygia crossing the visual axis cause irregular astigmatism that is not correctable with spherocylindrical spectacles. anterior segment OCT and A-scan biometry measurements for cataract surgery planning are unreliable in eyes with significant pterygium-induced corneal distortion , excise the pterygium first and reassess.
Distinguish from pseudopterygium: A pseudopterygium is a conjunctival adhesion to the cornea following peripheral corneal disease (chemical burn, marginal ulcer, trauma). It can be distinguished from a true pterygium by passing a probe or blunt instrument underneath the bridge of tissue , a pseudopterygium can be elevated from the cornea at any point along its length, whereas a true pterygium is adherent to the cornea at its advancing head and body (probe cannot pass beneath the head).
Surgical Management
Conjunctival autograft (CAG) with fibrin glue: The current standard technique. After pterygium excision and preparation of the bare scleral bed, a free graft of superior bulbar conjunctiva (same size as the defect, stripped of Tenon’s capsule) is transposed and fixed with fibrin glue (Tisseel). Glue fixation reduces operating time compared to sutures, produces equivalent or better outcomes, and causes less patient discomfort. A correctly oriented, tension-free graft with good contact to the scleral bed is the key technical factor in preventing recurrence.
Intraoperative MMC: 0.02% MMC applied on a sponge to the bare scleral bed for 1-3 minutes after excision, then washed out with saline, reduces recurrence in high-risk cases. The dose and duration are lower than for trabeculectomy. Risks: scleral melting, corneal edema from limbal damage, secondary infection , use the lowest effective dose and limit to cases where recurrence risk is genuinely high.
Amniotic membrane transplantation (AMT): Alternative to CAG in patients with limited superior conjunctival reserve (prior glaucoma filtering surgery, previous upper lid surgery), severe dry eye disease where conjunctival graft healing is impaired, or recurrent pterygium. AMT provides a scaffold for ocular surface reconstruction. Recurrence rates with AMT are higher than with CAG in primary pterygia , approximately 10-20% , but acceptable in selected cases. Cryopreserved (Prokera ring format) or dehydrated forms are available.
Postoperative Care and Recurrence Management
Postoperative drops: Topical antibiotic (chloramphenicol or fusidic acid) for 2 weeks; topical corticosteroid (dexamethasone 0.1% or prednisolone acetate 1%) tapering over 6-8 weeks to reduce subconjunctival fibrosis and graft inflammation. Preservative-free lubricants long-term for ocular surface support. Topical NSAID (ketorolac or diclofenac) in the first 1-2 weeks for postoperative pain.
Recurrence management: Re-excision is more technically demanding and carries higher recurrence risk than primary excision. MMC adjunct is more consistently used. Subconjunctival bevacizumab (anti-VEGF) injections at the recurrence site have modest evidence for reducing recurrence rate. Radiotherapy (strontium-90 beta irradiation) to the bare scleral bed immediately post-excision is used in some centers for recurrent pterygia , reduces recurrence but carries long-term scleral and limbal toxicity risks if used on primary excisions.
Clinical Decision Points
- Pterygium head 2 mm from visual axis, BCVA 6/6, no progression over 2 years: Observe. Document size with slit-lamp photography. Annual review. No surgical indication yet.
- Pterygium head 1 mm from visual axis, progressed 1.5 mm over 12 months, BCVA 6/9: Surgical indication , approaching visual axis with documented progression. Excision with CAG preferred. Discuss recurrence risk (below 10% with autograft) and UV protection post-operatively.
- Cataract with concurrent pterygium, astigmatism 2.5 D: Excise the pterygium first (at least 3-6 months before cataract surgery). Measure corneal topography and biometry after pterygium excision for accurate IOL calculation. Proceeding with cataract surgery without addressing the pterygium risks significant postoperative refractive error from unresolved induced astigmatism.
- Recurrent pterygium, second recurrence: Re-excision with MMC adjunct and consider radiotherapy discussion. Review UV protection compliance. Ensure CAG with healthy conjunctival tissue is used, not AMT.
When to Expedite
- Pterygium head crossing the visual axis , urgent excision to prevent further vision loss from central corneal involvement
- Rapid growth with irregular surface and prominent vascularity in an older patient , biopsy to exclude conjunctival squamous cell carcinoma (OSSN , ocular surface squamous neoplasia), which can clinically mimic pterygium
Ocular surface squamous neoplasia (OSSN) is a spectrum from dysplasia to invasive squamous cell carcinoma of the conjunctiva. It can look strikingly similar to pterygium , gelatinous, vascularized, advancing over the cornea. Features that should raise suspicion: unusual vascularity (leash of dilated feeder vessels), irregular surface, rapid growth, papillary surface, involvement of the corneal epithelium in a diffuse pattern, and failure of the lesion to explain the degree of symptoms. Any excised pterygium specimen should be sent for histopathology.
Clinical Pearls: Pterygium
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Every excised pterygium should be sent for histopathology. OSSN mimics pterygium perfectly.
Ocular surface squamous neoplasia (OSSN) , conjunctival intraepithelial neoplasia through to invasive squamous cell carcinoma , can be indistinguishable from pterygium clinically. The incidence of OSSN in excised pterygium specimens is reportedly 0.1-1.5% in published series. Missing this diagnosis at the time of excision has serious consequences. Routine histopathological examination of all excised tissue identifies OSSN cases that would otherwise be incompletely excised and inadequately followed. The cost is minimal and the consequence of missing an OSSN is high.
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Operate before cataract surgery, not after. Pterygium-induced astigmatism makes IOL calculation unreliable.
A significant nasal pterygium flattens the cornea in the horizontal meridian, inducing with-the-rule astigmatism. This astigmatism distorts keratometric and topographic measurements used for IOL power calculation. If cataract surgery is performed with the pterygium in situ, the refractive result is unpredictable , and when the pterygium is later excised, the astigmatism changes, leaving the patient with significant postoperative refractive error. The correct sequence is always: excise pterygium, allow 3-6 months for topographic stabilization, measure biometry on the stabilized cornea, then plan cataract surgery. This sequence is frequently not followed, with predictable consequences.
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The conjunctival autograft is the operation. Everything else is technique.
The key determinant of recurrence is whether a healthy, correctly oriented, tension-free autograft of adequate size is placed on the bare scleral bed. Fibrin glue vs sutures, MMC adjunct vs no MMC, bevacizumab vs no bevacizumab , all matter modestly. A large, well-placed autograft from healthy superior conjunctiva consistently gives recurrence rates below 5%. A small, tension-stressed graft from suboptimal tissue will fail regardless of adjuncts. Surgical training in pterygium surgery should be assessed by graft quality and placement, not just operative time.
Further reading: AAO guidelines on conjunctival and corneal disease. For related anterior segment conditions see dry eye disease (often co-existing) and keratoconus (differential diagnosis for progressive corneal irregularity). Full context on the cornea and refractive surgery subspecialty page.