Nearsightedness is a refractive state in which parallel light rays are refracted through the eye’s refractive system and fall in front of the retina when the eye is not using accommodation. Therefore, myopic eyes cannot see distant targets clearly. If the target is gradually moved closer to the eye, the light emitted to the eye is spread out to a certain extent, forming the focus will move backward, and finally can fall on the retina, and can see clearly, so myopic eyes do not have obstacles when looking at the near. The main manifestation of myopia is the loss of distance vision, which may occur as a result of visual fatigue, exotropia, eye protrusion and fundus lesions (such as retinal detachment and macular degeneration).