1, eye use is an important factor During adolescence, the eye tissue in the developmental stage is delicate and fragile. During the long time of close work, the scleral tissue gradually stretches the spherical wall under the mechanical action of the extraocular muscles; at the same time, the continuous contraction of the muscles in the eye with regulating function affects the development of the eye, resulting in the formation of myopia due to the excessive anterior and posterior diameter of the eye. Children at this stage have a wide range of interests, a strong desire to learn, heavy homework, read more books, love to surf the Internet, watch TV, outdoor activities, the eyes are in a long-term visual state; coupled with the lack of attention to eye hygiene, such as reading distance too close, reading posture is not correct, long time reading books and forget to rest, etc. 2, uneven lighting: such as a lone lamp lighting can produce shadows, uneven light and dark make ciliary muscle regulation disorder. 3, visual space limitations: long-term inability to see far so that the human eye produces regulatory adaptation, that is, only to meet the need to see near, resulting in myopia. 4, the pollution of the light environment: circadian rhythm is necessary for the normal growth and development of the human eye. There are reports: children who sleep with lights on are more myopic.