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JD Twelker, IL Bailey; An Age-Matched Case-Control Study of Risk Factors for Primary Pterygium . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3065.
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Purpose: A pterygium is a triangular corneal lesion, usually located on its nasal and interpalpebral surface. We investigated some potential risk factors for the occurrence of primary pterygium. Methods: A clinic-based, age-matched study of 90 case-control pairs was completed. The main outcome measure was the presence or absence of primary pterygium. The exposure variables included gender, education, income, family history of pterygium, latitude of residence, weekly sunlight exposure, and some biometric measures. Biometric measures included refractive error, anterior chamber depth, corneal diameter, central corneal power, peripheral corneal power, and the temporal catchment angle. The temporal catchment angle is the range of incident light angles at the temporal limbus over which nasal limbal light focusing occurs. We used a conditional logistic regression model to estimate odds ratios for exposure variables. Results: Using multivariate modeling, four factors in combination best predicted the occurrence of primary pterygium (R-squared = 0.53, p < 0.0001). All other exposure variables did not significantly contribute to the model at the 95% confidence level. The odds ratio for a family history of pterygium was 1.40 (1.01, 1.95; p=0.046). The odds ratio for latitude of residence from birth to 16 years was 0.28 (0.12, 0.67; p=0.004) for a 10 degree northerly shift in latitude. The odds ratio for sunlight exposure from ages 16-30 years was 3.60 (1.96,6.55; p<0.0001) for an increase of 6 hours per week. The odds ratio for increasing magnitude of the temporal catchment angle was 2.29 (1.17, 2.12; p=0.016) for an increase of 10 degrees. Conclusion: The most important risk factors for the development of pterygium are a family history of pterygium, latitude of residence in youth, sunlight exposure, and the temporal catchment angle. This information could contribute to future prevention programs or studies of pterygium.
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