Risk Factors for Childhood Myopia: Findings From the NICER Study

We explored risk factors for myopia in 12- to 13-year-old children in Northern Ireland (NI). Stratified random sampling was performed to obtain representation of schools and children. Cycloplegia was achieved using cyclopentolate hydrochloride 1%. Distance autorefraction was measured using the Shin-Nippon SRW-5000 device. Height and weight were measured. Parents and children completed a questionnaire, including questions on parental history of myopia, sociodemographic factors, childhood levels of near vision, and physical activity to identify potential risk factors for myopia. Myopia was defined as spherical equivalent ≤-0.50 diopters (D) in either eye. Data from 661 white children aged 12- to 13-years showed that regular physical activity was associated with a lower estimated prevalence of myopia compared to sedentary lifestyles (odds ratio [OR] = 0.46 adjusted for age, sex, deprivation score, family size, school type, urbanicity; 95% confidence interval [CI], 0.23-0.90; P for trend = 0.027). The odds of myopia were more than 2.5 times higher among children attending academically-selective schools (adjusted OR = 2.66; 95% CI, 1.48-4.78) compared to nonacademically-selective schools. There was no evidence of an effect of urban versus nonurban environment on the odds of myopia. Compared to children with no myopic parents, children with one or both parents being myopic were 2.91 times (95% CI, 1.54-5.52) and 7.79 times (95% CI, 2.93-20.67) more likely to have myopia, respectively. In NI children, parental history of myopia and type of schooling are important determinants of myopia. The association between myopia and an environmental factor, such as physical activity levels, may provide insight into preventive strategies.