Handing it to pterygium: Explaining pterygium laterality.

Purpose: To evaluate any correlation between pterygium laterality and patient handedness.

Methods: Our study represents a retrospective observational study of a series of consecutive pterygium patients recruited from two centres. Each patient was assessed for their handedness which was compared to the laterality of their presenting pterygium. Patients that possessed bilateral disease comparisons between pterygium size and handedness were made. Correlation statistics were performed to compare patient handedness and pterygium location (right or left). For patients possessing bilateral disease only, the pre-surgical differences between lengths and areas of pterygium were calculated and compared.

Results: A total of 219 patients were recruited into our study. 172 patients possessed unilateral disease and in 47 patients, the disease was bilateral. A significant association was identified between handedness and pterygium laterality (p < 0.001). Patients with right-sided pterygia were more likely to be right-handed (OR 2.327) and left-sided presentations who were more likely to be left-handed (OR 5.717). For bilateral presentations, patients were found to have longer (mean increase 3.50 ± 0.47 mm) and larger (mean increase 4.38 ± 0.48 mm) pterygia in the eye ipsilateral to their dominant hand.

Conclusions: A new insight of handedness as a contributing factor to pterygium laterality is consistent with evidence relating to the asymmetrical development of cortical cataract as well as to theories underlying the geometry of ocular UV exposure. A more complete understanding of factors contributing to ocular insolation may further inform as to improved protective measures and provides further evidence for the role of peripheral light focusing in pterygium pathogenesis.