[Medical Q&A] How does myopia occur? How can it be prevented?

Planner: Chinese Medical Association

Reviewer: Liu Wen, deputy chief physician, Beijing Children's Hospital, Capital Medical University

Myopia is a common vision problem, especially among children and teenagers. The main reason for myopia is that the eye length increases, so that the light entering the eye cannot focus accurately on the retina, but focuses in front of the retina. As a result, distant objects become blurry.

Under normal circumstances, after light enters the eye, it is refracted by the cornea and lens to accurately form a clear image on the retina. However, if the anterior-posterior diameter of the eyeball (the eye axis) is too long, the light will focus before reaching the retina, resulting in myopia. This usually occurs in children and adolescents because their eyeballs are still developing. Reading, doing homework, playing with mobile phones or computers for a long time will keep the eyes in a state of adjustment. The muscles of the eyes are always tense and cannot get a rest. Over time, the eye axis will become longer, and myopia will occur. In addition, if the parents have myopia, the probability of the child suffering from myopia will be higher. This is because myopia has a certain genetic tendency.

Preventing myopia needs to start with lifestyle habits. Parents can take the following measures to help their children prevent myopia. First, control the time of using electronic devices. It is recommended not to use electronic devices for too long every day. Take a break every 20 minutes and look into the distance to relax your eyes. Secondly, you can increase outdoor activities. Ensure at least 2 hours of outdoor activities every day to expose your eyes to natural light. Thirdly, maintain good eye habits. Keep the correct posture and appropriate distance when reading and writing, and the light should be sufficient but not too strong. Finally, check your eyesight regularly. It is recommended to take your children for regular vision checks to detect and treat early.