Determinants of the Age of Myopia Onset in Singaporean Children

Abstract

Purpose: : To determine the predictors of the age of myopia onset in a school-based cohort study of Singapore children.

Methods: : A prospective cohort study consisted of children aged 6 to 9 years at entry in two schools in 1999 and one school in 2001. These children were followed for a maximum of 9 years. Children (n=1031) with myopia (spherical equivalent ≤ -0.50 diopters) at the last follow-up visit were included in the analysis. Each participant underwent yearly comprehensive eye examinations including cycloplegic refraction and ocular biometric measurements. The main outcome was age of myopia onset, determined by annual refractive error examinations from ages 6 to 9 years onwards and through a questionnaire if the child was myopic at the baseline visit. A general questionnaire was administered consisting of demographics, family history, and amount of outdoor and near-work activity. Height and weight were measured according to standard protocols and IQ was assessed using the non-verbal Raven IQ test.

Results: : The mean age of myopia onset was 8.44 years old (95% confidence interval 6.37 to 10.51 years). The age of myopia onset differed by weight (multivariate adjusted mean = 8.10 versus 8.81 years old for children in lowest and highest quartiles, respectively; p=0.001), height (8.00 versus 8.85 years old for children in highest and lowest quartiles, respectively; p=0.002), parental myopia (8.41 and 7.99 years old for children with 1 and 2 myopic parents, respectively, versus 8.84 years for children with no myopic parents; p<0.001), ethnicity (8.41 versus 8.52 years old for Chinese and Malay children, respectively; p=0.031), and IQ (8.26 versus 8.65 years old for children in highest and lowest tertiles, respectively; p=0.027). Multivariate adjustments for age, gender, ethnicity, school, father’s education level, parental history of myopia, book reading, outdoor activity, height, weight, and IQ were conducted.

Conclusions: : In Singapore children, lower weight, greater height, parental myopia, Chinese ethnicity, and higher IQ were associated with earlier age of onset of myopia.

Keywords: myopia • clinical (human) or epidemiologic studies: risk factor assessment • visual development: infancy and childhood