The incidence of myopia in children is getting higher and higher, the age is getting lower and lower, the country now attaches great importance to the prevention and treatment of vision, in order to prevent myopia, we must know what causes myopia in the end, it is currently believed that the main three major reasons, as follows: 1, high-intensity close-up eye: generally remember the 20-20-20 rule, that is, after 20 minutes of eye contact, look away from 20 feet, or 6m away, relax the eyes for 20 seconds, it is easy to do, can be very effective in relieving the symptoms of eye fatigue. The rule of 20-20-20 is to remember that after 20 minutes of eye use, look 20 feet into the distance, that is, 6m away, relax your eyes for 20 seconds, it is easy to do, can be very effective in relieving eye fatigue symptoms, so that the eyes can achieve the purpose of resting. 2, too much, too early in the use of electronic products: nowadays, learning can not be separated from the electronic products, but the children’s contact with electronic products, myopia prevention is not very favorable, so it is recommended to minimize the use of the age of the younger the more it is not recommended to use, if you have to use, it is recommended to put font Enlargement, distance farther, in the family can find ways to put the phone, tablet on the content, projection to the projector, computer screen or TV screen, can play a certain role in alleviating. 3, outdoor activities time is not enough: it is recommended that the kindergarten three hours a day, more than two hours a day in elementary school outdoor time, outdoor does not necessarily have to exercise, as long as the stand in the outdoor walking even if even outdoors, reading, can also play a role in protecting vision. Reading, can also play a role in protecting eyesight, and the third method, is the most effective, but also free of charge, so it is recommended that parents must take their children more outdoor activities, in order to effectively prevent myopia occurs.