It turns out mom wasn't merely overselling the purported benefits of "playing outside" in her own selfish bid for "peace and quiet."

Two new scientific studies bolster evidence that spending time outdoors may help to prevent or mitigate nearsightedness in children, with papers published in the May issue of Ophthalmology, the journal of the American Academy of Ophthalmology.

A study conducted in Taiwan, the first to tie educational policy to vision health intervention, found a reduced risk of nearsightedness among children required to spend recess time outdoors. In Denmark, researchers found a direct correlation between seasonal fluctuations in daylight, eye growth, and the rate of progression of myopia.

Though correctable, the condition is also linked to development of severe eye problems in adulthood, which increases risk for glaucoma and retinal detachment, diseases that can blind. Though the condition is heritable, researchers believe environmental factors might explain a surge in myopia in populations around the world. In the United States, the condition has increased by more than 65 percent since 1970, and is approaching an epidemic status in Asia and other regions of the world, primarily in developed countries.

In the Taiwan study, researchers began by hypothesizing that greater time spent outdoors would affect myopia rates - and it did. A similar school nearby was used as a control group, seeing no improvement in comparison with the intervention school, which now required 80 minutes of outdoor recess time.

During the 2009 to 2010 study, children at both Taiwanese schools received eye exams at the beginning and end of the study, with researchers recommending schools add frequent recess breaks to help children's eye development and vision.

"Because children spend a lot of time in school, a school-based intervention is a direct and practical way to tackle the increasing prevalence of myopia," said Dr. Pei-Chang Wu, of Kaohsiung Chang Gung Memorial Hospital in Kaohsiung, Taiwan, who led the study.

The Danish study, analyzing data collected in a clinical trial in 2005, found a correlation between time spent in daylight - whether outside playing or merely meandering at a slow pace - lessened the chances of developing myopia. The researchers divided the schoolchildren into seven groups, each representing a different seasonal interval in daylight hours, which fluctuate from seven hours in winter to nearly 18 hours in summer. In children exposed to fewer hours of daylight, axial length of the eye grew at a higher rate, a measurement indicating a worsening of myopia.

Dr. Dongmei Cui, of Sun Yat-sen University in China, led the study of Taiwanese schoolchildren. "Our results indicate that exposure to daylight helps protect children from myopia," he said. "This means that parents and others who manage children's time should encourage them to spend time outdoors daily."

In the case of inclement weather, the use of daylight-spectrum indoor lighting should be considered as a way to minimize myopia, he said.