Pterygium

Pterygium is a wing shaped fibrovascular growth of degenerate conjunctiva that extends onto the cornea, usually from the nasal side, and may advance across the visual axis.

• Strongest risk factor: chronic ultraviolet exposure (outdoor work, tropical and subtropical latitudes, low altitude beaches), together with wind, dust, and dryness.
• Pathogenesis: limbal stem cell damage with inflammation, angiogenesis, growth factor release (VEGF, TGF-beta), matrix remodelling, and fibroblast proliferation.
• More frequent in men, ages 20 to 50 years, and in outdoor workers; it is often bilateral.
• Differential diagnosis: pinguecula (conjunctival elevation not reaching cornea), ocular surface squamous neoplasia (leukoplakic, gelatinous, or papillomatous lesion), conjunctival pseudopterygium (from corneal burn), and conjunctival naevus.

• Foreign body sensation, redness, tearing, dryness, and cosmetic concern.
• Triangular fleshy vascularised tissue with a head (apex) on the cornea, a neck at the limbus, and a body on the conjunctiva; an iron line (Stocker line) may lie in front of the advancing head.
• Astigmatism and visual loss when it progresses toward the pupil, restriction of ocular motility in large or recurrent lesions.
• Inflamed pterygium: injection with symptoms; Dellen or thinning near the head.

• Slit lamp assessment of extent (length onto cornea), thickness, vascularity, and activity.
• Corneal topography for induced astigmatism.
• Histology of any suspicious, atypical, or recurrent lesions to exclude ocular surface squamous neoplasia.
• Document and photograph for monitoring growth.

• Conservative therapy: UV-protective sunglasses with a hat, lubricants (preservative free drops 4 times daily), and short courses of topical anti-inflammatory therapy for inflamed lesions (fluorometholone 0.1 percent four times daily for 1 to 2 weeks, or loteprednol 0.5 percent). Vasoconstrictors should be used sparingly.
• Indications for surgery: threat to the visual axis (encroachment above 2 to 3 mm onto the cornea), induced astigmatism over 1 to 2 dioptres, recurrent inflammation not controlled medically, restricted motility or diplopia, or cosmetic indication.
• Surgery:
  • Excision of the pterygium with conjunctival autograft from the superior bulbar conjunctiva of the same eye, secured with fibrin glue (less pain, shorter surgery, and lower recurrence) or 8-0 or 10-0 absorbable sutures. Recurrence is under 5 to 10 percent with autograft versus 30 to 80 percent after bare sclera excision.
  • Intraoperative mitomycin C 0.02 percent on a sponge for 2 to 3 minutes (or 0.04 percent for 1 to 2 minutes) to the bare sclera in recurrent or high risk cases, with copious irrigation. Mitomycin carries a risk of scleral melt, so use with care.
  • Amniotic membrane transplantation, conjunctival rotational flap, and limbal conjunctival autograft for recurrences and large defects; adjunctive subconjunctival or topical anti-VEGF (bevacizumab 1.25 mg in 0.05 mL) to reduce recurrence is investigational.
• Postoperative treatment: topical antibiotic (moxifloxacin 0.5 percent four times daily for 1 to 2 weeks), topical corticosteroid (prednisolone acetate 1 percent four times daily tapered over 6 to 8 weeks), and lubricants; oral analgesia.
• Follow up: day 1, week 1, week 4, then 3 months, since recurrences occur within 6 months (growth tissue crossing the limbus).
• Complications: recurrence, graft retraction or dehiscence, granuloma, dellen, scleral melt, symblepharon, diplopia, and infection.