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Describe pterygium with its aetiology and management.

Ophthalmology · 3rd Professional

Nature and Aetiology

A pterygium is a triangular, wing-shaped fold of degenerative fibrovascular tissue encroaching from the bulbar conjunctiva onto the cornea, characteristically in the interpalpebral fissure and medially (nasally).

Aetiology — the dominant factor is ultraviolet-B exposure, and the disease follows a "pterygium belt" within 30 degrees of the equator, which includes most of India. Also implicated: chronic dryness, dust, wind and heat; and outdoor occupation — farmers, fishermen, construction and roadside workers
Why nasal and why in the fissure — light entering temporally is focused by the cornea onto the nasal limbus (the "peripheral light focusing" effect), delivering up to twenty times the incident dose there; and the interpalpebral zone is the exposed area. This explains the characteristic site, and a pterygium in any other position should raise doubt about the diagnosis

Part	Description
Head (apex)	The advancing tip on the cornea, preceded by a grey infiltrate (the cap or halo), and often with an iron line (stocker’S line) at its leading edge.
Neck	The constricted part at the limbus
Body	The triangular bulbar portion, adherent to the underlying sclera and moving with the conjunctiva
Progressive type	Thick, fleshy, vascular, with an infiltrated cap and obscuring the underlying episcleral vessels
Atrophic (stationary) type	Thin, pale, poorly vascular, with visible episcleral vessels through it and often a Stocker line

Surgery, Recurrence and Applied Aspects

The problem OF surgery IS recurrence, and it dominates the whole subject. Recurrence is more aggressive and more vascular than the original, and is commoner in the young, in the dark-skinned, and in fleshy progressive lesions
Bare sclera excision alone has a recurrence rate of 30 to 80% and should not be used — this is the single most important operative point
Conjunctival autograft is the operation of choice: the pterygium is excised and the bare area covered with a free graft of conjunctiva taken from the superior bulbar area, secured with sutures or fibrin glue. Recurrence falls to 2 to 5%. The graft restores a limbal barrier and normal conjunctival tissue
Limbal-conjunctival autograft includes limbal stem cells and may reduce recurrence further; amniotic membrane graft is used where conjunctiva is scarce or must be preserved for future glaucoma surgery
Adjunctive mitomycin C reduces recurrence but carries serious risks — scleral melting, avascular necrosis, secondary infection and perforation, sometimes years later — and is used sparingly, in low concentration and for a short application

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