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R. J. Mack, I. Shaikh, S. J. Farley, C. Caldwell, E. Chaglasian; Myopia and Sun Exposure: Patients With Pingueculum and Pterygium Are Significantly Less Myopic. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1697.
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About one third of adults in the US are myopic. Despite the high prevalence and significant morbidity of myopia, little is known about the etiology of the condition. Recently, however, one study correlated higher levels of childhood sun exposure with a reduced risk of myopia. Pingueculum and pterygium are likewise firmly associated with childhood sun exposure, but we could find no data on refractive errors in these two conditions. We gathered refractive data on patients with pingueculum and pterygium to identify any differences in refractive error from the general population.
Patients aged 21 or older and who were diagnosed by one cornea specialist with pingueculum or pterygium were included in this retrospective study. Refractive error was assessed in manifest refraction, spectacles, uncorrected acuity, and corneal topography. It was compared to age matched controls seen by the same doctor for conditions unrelated to sun exposure or refractive error. Data were analyzed using the chi square test.
61 patients with pingueculum or pterygium in at least one eye were analyzed. Less than two percent of eyes in patients with pingueculum or pterygium showed more than 0.5 D spherical equivalent of myopia, compared to 31% of age matched controls in our study. The average spherical equivalent in the pingueculum and pterygium groups was +0.65 D (range, SD; -0.5 - +1.6, +.48). The average spherical equivalent among age matched controls was -0.87 D (range, SD; -3.75 - + 1.5, +2.52). Chi Square analysis revealed p < 0.001. The refractive error in our age-matched controls was similar to that of patients in the Beaver Dam Eye Study.
Patients with pingueculum and pterygium were much less likely to be myopic than their age matched peers in our study. This supports but does not prove the hypothesis that childhood sun exposure is associated with a decreased risk of myopia.Keywords: myopia, pterygium, pingueculum, refractive error, sun exposure
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