Table 1.

Summary of results of studies included in the review

Review & type of study	Aim of study	No. of primary studies (sample size)	Types of studies included in the review	Ethnicity/ Location	Age range (years)	Definition of myopia (in Diopter sphere)	Intervention	Measuring tool	Conclusion
Anne-SuhrThykjær, et al. (2016) SR	To examine the association between physical activity and the development and progression of myopia	9 (17,634)	Cross-sectional, cohort, case control	Ireland, Britain, Netherlands, Australia, Finland, Singapore, USA, Jordan	7-20 years, 33-37 years	-0.25, -0.50, -0.75, -1.00	Physical activity	Subjective and objective utilities to quantify amount of PA (Questionnaire and accelerometer)	No evidence of physical activity having any effect on myopia
Justin C. Sherwin et al. (2012) SR and MA	To summarize relevant evidence investigating the association between time spent outdoors and myopia in children and adolescents	23 (33,926)	Cross-sectional, cohort, randomized controlled trial	East Asian and Non east Asian (USA, Singapore, Australia, Jordan, China)	6-18 years, 11-20 years, and 6-72 months	-0.25 DS	Time spent outdoors	The sum of general activities, leisure activities, and sports performed outdoors	Increasing time spent outdoors is a simple strategy to reduce the risk of developing myopia and its progression
ShuyuXiong, et al. (2017) SR and MA	To evaluate the evidence for association between time outdoors and the prevalence, incidence, and progression of myopia	52 (66,379)	Cross-sectional, cohort, randomized, and controlled clinical trial	East Asia, Australia, French, UK, USA, and Turkey	6-18 years, 18-24 years, 6-72 months, and aged 50 years or older	-0.25 DS	Time spent outdoors	Subjective and objective utilities to quantify amount of time spent outdoors (Questionnaire and accelerometer)	Increased time outdoors is effective in preventing the onset of myopia, but ineffective in reducing progression in existing myopes
Hsiu-Mei Huang et al. (2015) SR and MA	To quantify the effect of near work activities on myopia in children	27 (25,110)	Cohort, cross-sectional	Asia, North America, Australia, Europe, and Middle East		-0.50 DS and above	Near activity	Near activity in questionnaires completed by parents, children or both.	Near work activities were associated with myopia and that increased diopter-hours of near work might increase myopia prevalence

SR: systematic review, MA: meta-analysis