History and exam

Key diagnostic factors

common

wing-shaped conjunctival overgrowth onto corneal surface

Pathognomonic of pterygia.

Usually occur in the interpalpebral region, usually from the nasal side, and are often bilateral.[15]​​

Consist of a cap of a sub-epithelial arc-shaped corneal opacity at the leading edge with a sub-epithelial brownish line of iron deposition known as Stocker's line, a head (white fibrous mass attached to cornea), and a body (fleshy, triangular-shaped fibrovascular tissue continuous with the conjunctiva at its base). [Figure caption and citation for the preceding image starts]: Pterygium: A) cap, B) head, C) bodyFrom personal collection of David O'Brart; used with permission [Citation ends].com.bmj.content.model.Caption@125b1e62

history of chronic ultraviolet light exposure

Frequently, a history is given of an outdoor occupation, or the patient resides or has spent considerable time in geographic areas within 40° latitude of the equator. Also commonly found in surfers and sailors.[1]​​[2]​​

ocular irritation, burning, and tearing

Frequent presenting feature. Occurs due to local inflammation and tear film disturbances or loss of epithelium overlying the pterygium.

Other diagnostic factors

common

altered ocular cosmesis

May trigger a closer examination of the eye that reveals pterygium.

blurred vision

Can be caused by an induced astigmatism, and increased ocular aberrations, due to an increased tear meniscus in front of the pterygium head resulting in localised surface flattening, or occasionally growth of the lesion into the corneal visual axis.[13]​​​[14]​ Such changes can be quantified by corneal topographical scanning and analysis.

uncommon

double vision

A rare feature, caused by tethering of the medial rectus.

Risk factors

strong

chronic ultraviolet (UV) light exposure

Although the aetiology of pterygium is not fully understood, chronic exposure to UV light is a major risk factor. Pterygia occur more commonly in those living in areas with high UV light exposure (within 40° latitude of the equator) and those who spend long periods outdoors (e.g., sailors, surfers, people with outdoor occupations).[1]​​[2]​​

increasing age

Studies show that prevalence of pterygium increases with age.[3]​[4]​[5]​

weak

family history of pterygium

Familial cases have been reported with suggested autosomal dominant inheritance. Such cases are rare and occur at a much earlier age (i.e., childhood, teens, and twenties) than usual.[1]​​[6][7][9]​​

chronic ocular irritants

This relationship is uncertain. One study reported an increased incidence of pterygium in sawmill workers.[6]

human papilloma and Epstein-Barr virus infection

The human papilloma and Epstein-Barr viruses have been suggested as possible pathogens in the aetiopathogenesis of pterygium. The evidence is uncertain.[6][8]​​[10]​​

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