It is estimated that the global number of myopic patients will reach 5 billion by 2050. There is currently controversy in the research world about whether computer screen or mobile phone activity is associated with increased myopia prevalence.
An increase in myopic patients may be related to the digital lifestyle of our modern world.1 It is no secret that digital screen time may correlate positively with myopia prevalence in children. The eyes of growing young people are particularly vulnerable to this risk factor for myopia development. The pandemic has increased screen time among children and adolescents through lockdown measures such as homeschooling. According to the United Nations Educational, Scientific and Cultural Organisation, approximately 1.37 billion students are affected by these lockdown measures in over 130 countries around the world.2 Outdoor recreational activities have also been reduced to a minimum, so that children and adolescents affected by lockdown spend most of their free time in front of a smartphone, television or computer screen.
For years, researchers have warned about the impact of screen time or mobile phone use on the eye growth of children and adolescents. Generation R is a large cohort study that investigated the relationship between increased computer use and the onset of myopia at age 9 in a total of 5,074 children from Rotterdam. The combination of close-up activities such as reading books or computer screen activities was associated with an increased prevalence of myopia in 9-year-old children.3-5 Another study showed an independent association between smartphone screen time and the occurrence of myopia in 418 students.6 A meta-analysis of 12 cohort studies and 15 cross-sectional studies with a total number of participants of 20,025 children came to somewhat different conclusions. Here, the following emerged: Only reading, and not watching television or playing computer games, was associated with an increased prevalence of myopia in children and adolescents between 6 and 18 years of age.7
According to a 2017 meta-analysis, engaging in outdoor recreational activities was associated with a reduction in myopia incidence and myopia prevalence. Myopia prevention in myopic and non-myopic eyes of children and adolescents was investigated. Compared to the control group, the intervention mentioned above was able to reduce the myopic shift by 0.3 diopters after 3 years.8 The study by He's research group confirms these research results. He et al. showed that an additional 40 minutes of daily outdoor recreation was associated with a 23% reduction in myopia incidence in children and adolescents.9 Wu's research group found that the risk of myopia progression in both myopic and non-myopic children was reduced by 54% with a simple weekly intervention: The children spent 11 hours on outdoor activities per week. Wu et al. observed a reduction in myopic shift of 0.23 diopters in myopic children and adolescents who consistently followed this measure. This was compared with a control group of myopic children and adolescents who did not use this myopia prophylaxis.10,11
The public health sector recommends 2 hours of outdoor recreational activities per day for children and adolescents.12 The World Health Organisation guidelines advocate keeping screen time below 1 hour for children aged 1-5 years. Digital detox for children and adolescents is a core element in myopia prevention for this vulnerable age group. Fine tuning of eye length growth occurs at the visual level. The leisure time behaviour of children and adolescents should therefore be as follows: Activities at short visual distances should be reduced and recreational activities with daylight exposure should be increased.
References:
1. Dolgin E. (2015). The myopia boom. Nature. 2015; 519: 276-278.
2. Bullimore M.A. et al. (2013). The risk of microbial keratitis with overnight corneal reshaping lenses. Optom Vis Sci. 2013;90:937-944.
3. Ohno-Matsui K. et al. (2015). International photographic classification and grading system for myopic maculopathy. Am J Ophthalmol. 2015; 159: 877-883.e7.
4. Chang L. et al. (2013). Myopia-related fundus changes in Singapore adults with high myopia. Am J Ophthalmol. 2013; 155: 991-999.e1.
5. Enthoven C.A. et al. (2020). The impact of computer use on myopia development in childhood: The Generation R study. Prev Med. 2020; 132: 105988.
6. McCrann S. et al. (2020). Smartphone use as a possible risk factor for myopia. (Clin Exp Optom)
7. Huang H.M. et al. (2015). The association between near work activities and myopia in children-a systematic review and meta-analysis. PLoS One. 2015;10:e0140419.
8. Xiong S. et al. (2017). Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review. Acta Ophthalmol. 2017;95:551-566.
9. He M. et al. (2015). Effect of time spent outdoors at school on the development of myopia among children in China: a randomized clinical trial. JAMA. 2015;314:1142-1148.
10. Wu P.C. et al. (2018). Myopia prevention and outdoor light intensity in a school-based cluster randomized trial. Ophthalmology. 2018;125:1239-1250.
11. Wong C. W. et al. (2020). Digital Screen Time During the COVID-19 Pandemic: Risk for a Further Myopia Boom? Am J Ophthalmol. 2020 Jul 30;223:333-337.
12. Ngo C.S., Pan C.W., Finkelstein E.A. A cluster randomised controlled trial evaluating an incentive-based outdoor physical activity programme to increase outdoor time and prevent myopia in children. Ophthalmic Physiol Opt. 2014;34:362-368.