Which statement about pterygium is NOT true?

• A. It is most commonly caused by UV light exposure
• B. It typically induces ATR astigmatism
• C. It primarily destroys Bowmans' membrane of the cornea
• D. It can be associated with Stocker's line

Answer: (B)

Pterygium alters the corneal surface by pulling on it from the nasal side, which tends to flatten the central cornea along the horizontal meridian. When the horizontal meridian flattens, the vertical meridian becomes relatively steeper, producing with-the-rule astigmatism. This is why the statement about ATR astigmatism is not true—the usual pattern is WTR, not ATR.

Other statements fit with common features: UV exposure is a well-established risk factor for pterygium, Stocker's line is a classic pigmented line at the leading edge, and the tissue changes can involve Bowman's membrane, though describing it as being “primarily destroyed” simplifies the process—the pathology is more accurately a conjunctival invasion with subepithelial scarring and disruption of Bowman's layer rather than an outright destruction in all cases.