Daylight minimizes risk of myopia in children

Two studies from China and Denmark have associated spending time outdoors in daylight with a reduced risk of myopia, or nearsightedness, in children.

Researchers in Taiwan investigated 1 elementary school (intervention school) that required its 333 students aged 7 to 11 years to spend 80 minutes a day outdoors for the year 2009-2010. A similar school that did not require outdoor recess served as the control group of 238 children of similar ages. Both groups of students received eye exams when the study began and again 1 year later. Results showed that significantly fewer children became nearsighted in the intervention school compared with the control school (8.41% vs 17.65%, respectively).

In the second study, Danish researchers analyzed data collected in a 2005 clinical trial that included 235 school children with myopia aged 8 to 14 years. The children were divided into 7 groups, each representing seasonal intervals of daylight from 7 to 18 hours. Axial eye length (distance from the front to the back of the eye) and vision were tested at the beginning and again at the end of their seasonal intervals for elongation of the eye that would indicate myopia was worsening. Eye growth in the children with the least access to daylight averaged 0.19 mm; in children with access to the most daylight, eye growth measured 0.12 mm.

Both sets of investigators concluded that exposure to daylight protects children’s eyes from myopia, and that parents and caregivers who manage children’s time should make sure that children spend time in outdoor activities each day to minimize their risk for nearsightedness.

Myopia in childhood is correctable, but it can develop into more severe forms of glaucoma and retinal detachment in adulthood. In the United States, nearsightedness has increased by more than 65% since 1970.