Ethnic Differences in the Prevalence of Myopia and Ocular Biometry in 10- and 11-Year-Old Children: The Child Heart and Health Study in England (CHASE)

Myopia is the most common cause of correctable visual impairment in the developed world and a leading cause of preventable blindness in developing countries.1 Reduced vision in childhood is predominantly due to myopia,2–5 with a shift toward higher levels of myopia with increasing age.6 Poor vision as a consequence of uncorrected refractive error has been identified as a priority area by the World Health Organization's global initiative to eliminate avoidable blindness by the year 2020.7 Geographic variations in myopia prevalence are marked in both child and adult populations with the highest levels of myopia in East Asia, where approximately 80% of young adults are myopic.8,9 Compared to East Asian children the prevalence of myopia is lower in children from South Asia.10,11 The lowest prevalence appears to be in white children,12–14 with similarly low levels of myopia in children of African Caribbean origin.3,15,16 These variations together with the recent rapid increases in the prevalence of myopia (especially among children in Asia17 and in higher income countries,18) suggest that environmental factors are important determinants of myopia17 and hence of reduced unaided distance vision.14 Axial length is a key determinant of the degree of myopia.19,20 Thus, it is likely that ethnic differences in myopia prevalence would reflect ethnic differences in ocular biometry. However, few studies have examined these differences in children.3,21,22 The population prevalence of childhood myopia is not well characterized in the United Kingdom, and little is known about levels of myopia in ethnic minority groups. We therefore examined ethnic differences in the prevalence of myopia and ocular biometry among children of white European, South Asian, and African Caribbean origin, who shared similar geography (resident in London or the Midlands) and schooling. Ocular and potential sociodemographic determinants of myopia in these children were explored.