Pterygium
Definition
A fibrovascular growth of bulbar conjunctiva that encroaches onto the corneal surface, typically arising from the nasal limbus, associated with chronic UV exposure and ocular surface inflammation.
Clinical Snapshot
Pterygium is a fibrovascular proliferation of bulbar conjunctiva that encroaches onto the corneal surface, typically arising from the nasal limbus. It is associated with chronic UV exposure, dry and dusty environments, and ocular surface inflammation. Pterygium is common in the "pterygium belt" — latitudes within 37° of the equator. Management ranges from observation and lubrication for small, stable lesions to surgical excision when vision, comfort, or contact lens wear is compromised.
Epidemiology
Prevalence ranges from 2–7% in temperate climates to over 20% in equatorial regions. It is more common in males, outdoor workers, and individuals with prolonged UV exposure. Recurrence after surgical excision is a significant clinical challenge, with rates of 30–80% after simple excision and 5–15% with conjunctival autograft.
Pathophysiology
UV radiation — particularly UV-B — induces oxidative stress and DNA damage in limbal epithelial cells, triggering abnormal proliferation and migration of fibrovascular tissue. Limbal stem cell dysfunction may contribute to the failure of normal epithelial barrier function at the limbus. Matrix metalloproteinases (MMPs) degrade the extracellular matrix, facilitating fibrovascular invasion of the corneal stroma. The resulting lesion contains fibroblasts, inflammatory cells, and abnormal extracellular matrix.
Risk Factors
- Chronic UV exposure (the primary risk factor)
- Outdoor occupation or lifestyle
- Low latitude (equatorial regions)
- Dry, dusty, or windy environments
- Male sex
- Ocular surface inflammation
Clinical Presentation
Pterygium presents as a triangular, fleshy, vascularized growth arising from the nasal (most common) or temporal limbus and extending onto the corneal surface. Patients may report redness, irritation, foreign body sensation, and cosmetic concern. Advanced lesions may induce irregular astigmatism, reduce visual acuity by encroaching on the visual axis, or interfere with contact lens wear. Stocker's line — an iron deposit at the advancing edge — indicates a slowly growing lesion.
Diagnostic Pearls
- Measure the extent of corneal encroachment — lesions approaching or crossing the visual axis require more urgent management.
- Corneal topography reveals induced irregular astigmatism even before the visual axis is involved.
- Stocker's line at the advancing edge indicates slow growth; its absence suggests more active progression.
- Distinguish pterygium from pseudopterygium (conjunctival adhesion to the cornea following inflammation or trauma) — a probe can be passed under a pseudopterygium but not a true pterygium.
Differential Diagnosis
- Pseudopterygium
- Conjunctival intraepithelial neoplasia (CIN)
- Squamous cell carcinoma of the conjunctiva
- Pinguecula (does not encroach onto the cornea)
Evidence-Based Management
Small, stable pterygium: preservative-free lubricants, UV-blocking sunglasses, and observation. Surgical excision is indicated for lesions approaching the visual axis, inducing significant astigmatism, causing persistent symptoms, or interfering with contact lens wear. Conjunctival autograft (CAG) with or without mitomycin C is the preferred surgical technique — it significantly reduces recurrence compared to bare sclera excision. Postoperative topical corticosteroids reduce inflammation and recurrence risk.
Monitoring & Follow-Up
Monitor size and progression at each visit. Photograph or diagram the lesion for longitudinal comparison. Corneal topography provides objective documentation of induced astigmatism.
Clinical Pearls
- UV protection (sunglasses, hats) is the most effective preventive measure — counsel all patients with pterygium or pinguecula.
- Conjunctival autograft dramatically reduces recurrence compared to bare sclera excision — refer to a surgeon experienced with this technique.
- Induced irregular astigmatism may persist after excision — corneal topography post-surgery guides optical management.
- Any atypical pterygium (rapid growth, leukoplakia, feeder vessels) should raise concern for conjunctival neoplasia — biopsy if in doubt.
Related Therapeutics — Clinician's Companion
- Anti-inflammatory Rescue — FML®, Pred Forte® (Clinician's Companion)
Key References
- 1.Clearfield E, et al. Conjunctival autograft for pterygium. Cochrane Database Syst Rev. 2016.
- 2.Liu L, et al. Pterygium: pathogenesis and treatment. Prog Retin Eye Res. 2013.
This entry is an educational reference designed to support clinical reasoning and awareness. It does not constitute medical advice, establish a standard of care, or replace individualized patient assessment. Clinicians should consult current guidelines and applicable clinical resources when making patient care decisions.