Relative contribution of risk factors for early-onset myopia in young Asian children

Purpose: To investigate the associations of near work, outdoor activity, and anthropometric risk factors with early-onset myopia in Singaporean preschool children. Methods: Pregnant women who attended their first-trimester clinic at two major maternity units were recruited for the GUSTO birth cohort (n = 1236). Cycloplegic autorefraction and axial length (AL) were obtained in 3-year-old children (n = 572). Parents completed detailed questionnaires on parental myopia, near work, and outdoor activities when the child was 2 years of age. Height and weight were measured in the children at various time points from birth to 3 years of age. Results: Among the cohort of 572 children, 35 children (6.1%) had early-onset myopia. In multivariable regression models, compared to children whose parents were not myopic, those with two myopic parents were more likely to have a more myopic spherical equivalent (SE) (regression coefficient: −0.36; 95% confidence interval [CI]: −0.61 to −0.11) and longer AL (regression coefficient: 0.24; 95% CI: 0.10–0.39) and more likely to have myopia (odds ratio [OR] = 4.8; 95% CI: 1.4–16.6). Neither near work nor outdoor activity was associated with SE, AL, and myopia. Taller children were found to have longer AL at birth and at 12, 24, and 36 months, but there were no associations with SE. Conclusions: Genetic factors may have a greater contribution to early development of refractive error compared to environmental factors.