It’s long been thought kids are more at risk of nearsightedness, or myopia, if they spend hours and hours in front of computer screens or fiddling with tiny hand-held electronic devices.

Not true, scientists say. Research suggests that children who are genetically predisposed to the visual deficit can improve their chances of avoiding eyeglasses just by stepping outside.

Sunshine – specifically, the natural light of outdoors – is all they need, and 14 hours a week of outdoor light should do it.

Why this is the case is not exactly clear.

“We don’t really know what makes outdoor time so special,” said Donald Mutti, the lead researcher of the study from Ohio State University College of Optometry, in a press release. “If we knew, we could change how we approach myopia.”

What is known is that UVB light, also known as invisible ultraviolet B rays, plays a role in the cellular production of vitamin D, which is believed to help the eyes focus light on the retina. However, the Ohio State researchers think there is another possibility.

“Between the ages of 5 and 9, a child’s eye is still growing,” Mutti said. “Sometimes this growth causes the distance between the lens and the retina to lengthen, leading to nearsightedness. We think these different types of outdoor light may help preserve the proper shape and length of the eye during that growth period.”

The scientists also are studying if visible light outdoors, not just UVB, might contribute to healthy eyesight. Even on an overcast day, outdoor light is at least 10 times brighter than indoor light, they said. When a person is outdoors, certain specialized cells in the retina control pupil dilation, letting in more or less light.

“Our initial research suggests that the pupil responds more if these cells have been exposed to a lot of sunlight in the previous few days.”

Ultimately, there are more questions to be answered, Mutti said.