The more time children spend playing outside, the less likely they are to suffer from myopia, commonly known as nearsightedness. According to a report from Medical News Today, researchers from Sun Yat-sen University in Guangzhou, China have released a study in the journal JAMA outlining their findings.

Myopia occurs when a distortion in the eye’s lens distorts objects far away, but leave objects nearby clear. This can also occur when the eyeball takes an oblong shape instead of a sphere.

Evidence suggests that myopia can be hereditary, but new research has revealed that the stress to the eyes caused by too much work can have a significant impact as well.

The study found that rates of myopia are increasing across Europe and the Middle East, and are approaching “epidemic levels” in young adults in East and Southeast Asia, where it affects up to 90 percent of high school graduates.

The study examined 1,903 primary school students over the course of a 3-year period to see what effect one daily 40-minute outdoor activity session would have on the rate of myopia.

Half of the students were given the time to go outside and run around, while the other half served as a control group. They found that after 3 years, the rate of myopia in the students who participated in outdoor activities was 9.1 percent lower than the students who stayed inside.

There were 30,357 new cases of myopia in the United States in 2010, which is down from the level ten years prior. Myopia affects 54 percent of females and 46 percent of males in the U.S. Going outside and letting your eyes take a rest from reading a book or a screen may do them some good, and it could even save you a trip to the optometrist.