Too much time spent indoors may make children nearsighted. Not long ago people thought that reading too much was bad for the eyes, or that other forms of “close work” would lead to poor vision. Maybe there is something to that. Research over the last few years has revealed increasing rates of nearsightedness. In the US, about 30% of the population is nearsighted (Vitale et al. 2008). The incidence of nearsightedness has nearly tripled among African Americans. Much of the research on increasing rates of myopia has been done in Asia, where rates of nearsightedness, especially in children are particularly high and seem be rising.
Nearsightedness: too much time in front of a screen?
Is it too much time spent doing “close work” such as reading, video games, internet activity and/or homework? An alternative factor might be lack of sunlight. People (including children) who spend a lot of time on the computer, reading and doing homework are probably getting a lot less exposure to natural light. Of course there may be other factors in play, for example:
- less shifting of focus from near to far (which would happen during outdoor activity).
Or not enough sunlight?
Time outdoors is looking like the major factor. A recent study found that elementary school children who played outdoors during recess had better vision than those who spent recess time indoors. Students were ages 7 to 11 attending similar schools only a few miles apart. Students in both schools got 2 hours of outdoor physical education a week and 80 minutes of recess every day. Children had visual exams at the start of the study and an additional exam a year later. There were significantly fewer new cases of myopia in the children who got the extra 80 minutes of daily outdoor recess. This is a very exciting finding and an exciting area of research. How many of us have just assumed the need for glasses was genetic?
You can read more about environmental factors and nearsightedness in this excellent article by Tim Lougheed in Environmental Health Perspectives.
Vitale S, et al. Prevalence of refractive error in the United States, 1999–2004. Arch Ophthalmol 126(8):1111–1119 (2008); http://dx.doi.org/10.1001/archopht.126.8.1111.
Jones LA, Sinnott LT, Mutti DO, Mitchell GL, Moeschberger ML, & Zadnik K (2007). Parental history of myopia, sports and outdoor activities, and future myopia. Investigative ophthalmology & visual science, 48 (8), 3524-32 PMID: 17652719
Vitale S, Sperduto RD, & Ferris FL 3rd (2009). Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Archives of ophthalmology, 127 (12), 1632-9 PMID: 20008719
Wu PC, Tsai CL, Wu HL, Yang YH, & Kuo HK (2013). Outdoor activity during class recess reduces myopia onset and progression in school children. Ophthalmology, 120 (5), 1080-5 PMID: 23462271