A large myopia investigation study done in Taipei, Taiwan, has presented evidence of significant protective effects of three behaviors in myopic children: longer distance (>30cm) when doing near work, taking a break from near work every 30 minutes and more outdoor activity during recess. Children employing these protective behaviors consistently had a significantly lower prevalence of myopia, and the protective impact was statistically significant from six to 24 months.

The study assessed 10,743 students about 10 years old whose parents completed two-year refraction data and a questionnaire. Questions included the average time spent on near work each day, the distance from objects when doing near work and the number of breaks when doing near work for more than 30 minutes. Questions about outdoor behavior included the average time spent playing outdoors in school recess on weekdays.

In two years follow-up, the risk ratios after adjusting for background variables and the other two behaviors were 0.71 for near work distance, 0.89 for near work time and 0.77 for outdoor time. Additionally, the researchers found the distance of near work had an obvious protective effect and had a more statistically significant difference at every time point in two years than the other two behaviors. Students with shorter near work distance revealed the most myopic shift in spherical equivalent after adjusting for background variables.

The researchers believe that identifying the impacts of near working distance, continuous near work and outdoor activity on myopia prevalence and progression in children could help develop practical myopia prevention methods. 

Huang PC, Hsiao YC, Tsai CY, et al. Protective behaviours of near work and time outdoors in myopia prevalence and progression in myopic children: a 2-year prospective population study. Br J Ophthalmol. February 24, 2020. [Epub ahead of print].