Modern lifestyles and nutritional transition have given rise to an emerging epidemic of obesity and type 2 diabetes in developed and developing countries.^1,2 In general, metabolic compromise is seen in South Asians at relatively lower levels of obesity compared with Europeans, with Chinese having an intermediate relationship, suggesting that the patterns of development of obesity and metabolic function in different Asian populations merits focused investigation.³

Background: Due to high prevalence myopia has gained importance in epidemiological studies. Children with early onset are at particular risk of complications associated with myopia, as progression over time might result in high myopia and myopic macular degeneration. Both genetic and environmental factors play a role in the increasing prevalence of myopia. The aim of this study is to review the current literature on epidemiology and risk factors for myopia in school children (aged 6–19 years) around the world. Main body: PubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 2013 and Mar 2019 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Eighty studies were included in this literature review. Myopia prevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non-cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (73%), and high rates in North America (42%). Low prevalence under 10% was described in African and South American children. In recent studies, risk factors for myopia in schoolchildren included low outdoor time and near work, dim light exposure, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment. Conclusion: Low levels of outdoor activity and near work are well-established risk factors for myopia; this review provides evidence on additional environmental risk factors. New epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia. As the myopia prevalence rates in non-cycloplegic studies are overestimated, we recommend considering only cycloplegic measurements.

Purpose: Digital screen time has been cited as a potential modifiable environmental risk factor that can increase myopia risk. However, associations between screen time and myopia have not been consistently reported. Although myopia prevalence increased before the massive use of digital devices in some countries, with the rise being influenced by education, there may be an added recent effect of screen time. The aim of this systematic review is to determine the association between screen time and the risk of developing (1) prevalent or incident myopia, or (2) the risk of myopia progression in children. Published manuscripts were identified in PubMed, ScienceDirect and the Cochrane Library, and citation lists were reviewed. Recent findings: Fifteen studies were included (nine cross‐sectional and six cohort studies) with a total of 49 789 children aged between 3 and 19 years old. Seven studies found an association between screen time and myopia. The results showed mixed evidence with the more recent studies exposing a trend of association between hours spent by children using screens and myopia. Meta‐analysis using a random‐effects model was performed in five studies ( n = 20 889) that reported odds ratio (OR). The I ² statistics was used to assess heterogeneity. A pooled OR of 1.02 (95% CI: 0.96–1.08; p = 0.48) suggests that screen time is not associated with prevalent and incident myopia in this group of five studies. Summary: The results for screen time and myopia are mixed. Further studies with objective screen time measurements are necessary to assess evidence of an association between screen time and myopia.