Estimating heritability of refractive error in Koreans: the Korea National Health and Nutrition Examination Survey

Purpose: To estimate the familial correlation and heritability of refractive error in general Korean population. Methods: From the Korea National Health and Nutrition Examination Survey, 13 258 subjects of 7920 families, who were aged ≥19 years, were included in the study. Using variance components analysis, the additive genetic effect, or heritability, and the common and unique environmental effects on refractive error were examined, adopting common environments shared by cohabiting family or by siblings. Results: The proportions of hyperopia, myopia and high myopia in Koreans were 0.8%, 45.2% and 5.7% respectively. The correlation coefficients of spherical equivalent (SE) were 0.257 for parent–offspring pairs, 0.410 for sibling pairs and 0.112 for spouse pairs (p < 0.001 for all). Common environment shared by siblings affected the variation of SE significantly (p < 0.001), but that shared by cohabitants did not (p = 0.395). Adopting common environment shared by siblings, the heritability, common environmental effect and unique environmental effect of refractive error were 42.1 ± 3.3%, 11.8 ± 3.5% and 46.1 ± 3.9% respectively. Heritabilities of hyperopia, myopia and high myopia were 45.7%, 44.3% and 68.9% respectively. Adjusted odds ratios of myopia among offspring were 3.78 given one parent has myopia and 4.43 when both parents have myopia. Conclusion: Refractive error is influenced by common environment shared by siblings. The heritability of refractive error is higher for high myopia than for myopia or hyperopia.