Why can't the reading light be too bad?

Too strong or too weak light will affect children's eyesight and cause myopia. When the light is too weak, in order to see the words on the book clearly, the child has to hold the book very close, which also strengthens the adjustment of the eyes. After a long time, the eyes are tired and the vision gradually declines, which will form myopia. When the light is too strong, it will stimulate the eyes, make the pupils narrow, make the eyes tense, feel sore and tired. People's vision adjustment ability has a certain range. When the light is too strong and exceeds the ability of vision adjustment, it will also be harmful to vision. Natural light is most suitable for people's eyes, but natural light is only comfortable to read under scattered light, and eyes are not easily tired. If it is direct light, such as reading in the sun, it will be too dazzling.