Pterygium

Overview

Pterygium is a common, wing-shaped fibrovascular growth of degenerated conjunctival tissue that extends onto the corneal surface, typically on the nasal side of the eye.¹ The pathogenesis remains incompletely understood, but chronic ultraviolet (UV) light exposure is the most strongly and consistently implicated environmental trigger.¹

Epidemiology & Risk Factors

Pterygium is more common in populations with substantial outdoor UV exposure, particularly those living near the equator, and in individuals with occupational outdoor sun exposure (e.g., farmers, fishermen, outdoor laborers). Other associated factors include chronic dust/wind exposure and dry eye disease. It is generally more common in adults and increases in prevalence with age and cumulative UV exposure.

Pathophysiology

Pterygium pathogenesis is complex and incompletely understood; proposed mechanisms include UV-induced limbal stem cell alterations, local inflammation, and abnormal tissue remodeling with fibrovascular proliferation.¹ Molecular research has implicated interactions between the tumor suppressor p53 and its regulator MDM2 in pterygium tissue, an area of ongoing investigation that may also inform less toxic future adjuvant treatments.¹

Clinical Presentation

Many pterygia are asymptomatic or minimally symptomatic, noted incidentally on exam or by the patient as a visible growth on the white of the eye. Symptomatic patients may report foreign-body sensation, mild chronic redness, and cosmetic concern. As the lesion grows toward or onto the visual axis, it can induce irregular astigmatism and, eventually, direct visual axis obstruction, both of which are indications to consider surgery.

Exam Findings

• Triangular, fibrovascular conjunctival growth with its apex pointing toward the corneal center, typically nasal
• Associated conjunctival injection, particularly with active/inflamed lesions
• Stocker's line (iron deposition in the corneal epithelium anterior to the leading edge) in some chronic cases
• Induced corneal flattening/irregular astigmatism from traction as the lesion enlarges
• Direct visual axis involvement in advanced cases

Differential Diagnosis

• Pinguecula (a similar but non-corneal-involving conjunctival degeneration, does not cross the limbus)
• Conjunctival intraepithelial neoplasia or squamous cell carcinoma (can mimic an atypical or rapidly changing pterygium and should be considered, especially with atypical vascularity or gelatinous appearance)
• Pseudopterygium (a conjunctival adhesion to the cornea following prior inflammation, trauma, or surgery, rather than a primary degenerative growth)
• Mooren's ulcer or other peripheral corneal disease, in atypical presentations

Management

Most pterygia are managed conservatively with observation, UV-protective sunglasses, and lubricating drops for symptomatic relief. Surgical excision is considered for lesions that are visually significant (encroaching on or affecting the visual axis), rapidly growing, causing persistent irritation unresponsive to conservative measures, or of uncertain diagnosis where biopsy is warranted.

Pterygium excision with conjunctival autografting remains the preferred surgical technique to reduce recurrence compared with bare sclera excision alone.¹ Various adjuvant therapies have been used to further reduce recurrence, including topical cyclosporine, mitomycin-C (MMC), 5-fluorouracil (5-FU), and beta-irradiation, though these carry their own risk of adverse effects and are used selectively.¹ A meta-analysis comparing modified sutureless glue-free (using the patient's own blood for fixation) versus conventional sutured conjunctival autograft techniques found the sutureless approach had a shorter operation time and lower risk of foreign-body sensation, but a higher risk of graft dehiscence and retraction, with no significant difference in overall recurrence rate between the two techniques.²

Complications

• Recurrence — the classically most-discussed complication, though rates vary substantially by surgical technique and adjuvant use
• Conjunctival granuloma — in one long-term single-center series using conjunctival autograft with fibrin glue, granulomas were found to be more common than recurrence over an 11-year follow-up period³
• Graft-related complications specific to technique: dehiscence and retraction (more common with sutureless glue-free fixation), and foreign-body sensation (more common with sutured fixation)²
• Induced astigmatism and, rarely, diplopia from extraocular muscle involvement in very advanced cases
• Dellen formation adjacent to the excision site

Clinical Pearls

• Not all conjunctival growths near the limbus are pterygia — always consider conjunctival intraepithelial neoplasia in atypical-appearing or rapidly changing lesions
• Pterygium excision with conjunctival autograft is preferred over bare sclera excision to reduce recurrence¹
• Sutureless glue-free grafting is faster and more comfortable postoperatively but carries a higher risk of graft dehiscence/retraction than sutured fixation, with similar overall recurrence²
• Conjunctival granuloma is a recognized, and in some series more common, postoperative complication than recurrence itself — counsel patients accordingly³
• UV protection (sunglasses, hats) is both a preventive measure and appropriate ongoing counseling after surgery to reduce recurrence risk

Common Pitfalls

• Assuming every triangular conjunctival-corneal lesion is a benign pterygium without considering neoplastic mimics
• Recommending surgery for all pterygia regardless of visual/symptomatic significance
• Overlooking postoperative granuloma as a distinct complication from recurrence, potentially leading to unnecessary re-excision for recurrence when granuloma is the actual finding
• Using adjuvant therapies like mitomycin-C without appropriate patient selection, given their associated toxicity risk
• Failing to counsel patients on ongoing UV protection after surgery to reduce recurrence risk