Global epidemiology of myopi

Abstract

East Asia has been faced with an increasing prevalence of myopia and the same trend has been shown in other parts of the world to a lesser extent. In population-based studies on children, the prevalence of myopia varies highly between East Asian populations and other clusters, with generally lower prevalence in rural areas than in urban areas. These geographic and/or ethnic differences can be explained by genetic and/or environmental factors, as evidenced by studies on migrant populations. On the other hand, these differences are not pronounced in adult populations. High myopia may be associated with several ocular complications later in life and can be one of the main causes of visual impairment. In general, the risk of pathologic myopia (PM) increases with the severity of high myopia and age. The prevalence of visual impairment attributed to PM is 7% in Western populations and 12-27% in Asian populations. Studies have reported 25% of high myopia may develop PM; while 50% of those with PM may develop visual impairment as older adults. Based on the current prevalence of high myopia in young adults (6.7-21.6%) in East Asian countries, the prevalence of visual impairment attributed to PM may increase in the future, as these young adults get older. This chapter summarizes current population-based studies and highlights the world pattern and generational trends of the prevalence of high myopia and PM.