PurposeAmblyopia is a leading cause of vision impairment among children and young adults. Individual studies showed significant variations in the prevalence of amblyopia in different regions and age groups. This study is to estimate the global prevalence of amblyopia by pooling its prevalence from the previous studies and to project the number of people affected through 2040.MethodsWe performed a systematic review and meta-analysis on the prevalence of amblyopia using data published before 20 October 2018. We estimated the prevalence rate of amblyopia and its 95% CI globally and by subgroups (eg, region and age). The prevalence data were applied to United Nations World Population Prospects to derive the projected number with amblyopia through 2040.ResultsA meta-analysis of 60 studies (1 859 327 subjects) showed that the pooled prevalence rate of amblyopia was 1.44% (95% CI 1.17% to 1.78%). Prevalences in Europe (2.90%) and North America (2.41%) were higher than in Asia (1.09%) and Africa (0.72%). The highest prevalence was found in subjects over 20 years old (3.29%). There was no difference in the prevalence between genders. We estimated 99.2 (95% CI 71.7 to 146.1) million people with amblyopia in 2019 worldwide, increasing to 175.2 (95% CI 81.3 to 307.8) million by 2030 and 221.9 (95% CI 83.7 to 429.2) million by 2040.ConclusionsThe amblyopia is becoming a significant vision problem worldwide. It is of great importance to design and implement amblyopia screening, treatment and related public health strategies.

The prevalence of amblyopia and strabismus in preschool children in Eastern China were 1.20% and 5.65%, respectively. The refractive and strabismus are the main factors associated with amblyopia.

The prevalence of amblyopia in children 36-48 months old in Eastern China was 1.47%. The refractive error is a major risk factor for amblyopia.

The burden of reduced VA in preschool children in China was similar to that of Asian children of similar ages in the United States. Uncorrected refractive error and amblyopia were the principal causes for reduced VA among preschoolers (aged three to 6 years) in China.