Reading and writing are the main tasks during adolescence. It is well documented that reading and writing at too close a distance plays a decisive role in the formation of myopia. As you know, the human eye does not need to adjust when looking at a target beyond 5 meters; looking at a target within 5 meters requires adjustment, and the closer the target, the greater the adjustment used. When the target is 50 cm from the suit, it requires 2 diopters of adjustment, 25 cm requires 4 diopters of adjustment, and the required adjustment force rises sharply when the distance is less than 25 cm, which increases the adjustment of the ciliary muscle. As young students have more courses and homework, in order to complete homework and exams, they read and write for more than 10 hours a day, binding their vision to the near distance, and lacking knowledge of eye health, the ciliary muscle is over-regulated for a long time, causing regulation spasms and forming pseudomyopia, which over time turns into true myopia, and some develop into high myopia. Three “to” and three “one”. Three “to”: 1, reading and writing posture should be correct. 2. After 30 or 40 minutes of reading and writing, go outside or look into the distance for a while. 3. Do eye exercises carefully and choose the right points. Three “one”: 1, when reading and writing, the distance between the eyes and the book should be maintained one foot (30-35 cm). 2, the body and the desk to maintain a fist distance between. 3, keep an inch distance between your hand and the tip of the pen when holding the pen. In addition, when reading and writing should also pay attention to the angle of the book and the line of sight. When the plane of the book is at right angles to the line of sight, the image formed on the retina is the clearest, and the eyes are the most comfortable. If the book is placed on the horizontal desktop, reading books must be bowed forward to form close to the right angle, which can easily cause tension in the neck muscles and back spine fatigue, and can not maintain a reasonable distance. Therefore, the desktop is best not counted as having a slope of 12 ° to 15 °. So that the head is straight, not only to maintain the correct posture, but also to make the image more clear. In short, the distance between books and eyes when reading and writing, and the angle between books and vision are closely related to the formation of myopia, which should attract the attention of parents and teenagers.