The main factors in the formation of myopia are related to both elongation of the eye axis and excessive refractive power. The elongation of the eye axis causes the focal point formed by the parallel light rays entering the eye to be located in front of the retina, which is the most common cause of the formation of myopia, often referred to as axial myopia. 1. Developmental factors. In childhood, the eye is small and farsighted, and then gradually develops into an ortho-optic eye, but if the eye develops excessively, myopia is formed. 2. Environmental factors. In adolescence, the eye does not pay attention to eye hygiene during the developmental period and develops poor hygiene habits. Such as reading distance too close, improper lighting, excessive eye use and poor posture can contribute to the occurrence of myopia. 3. Genetic factors. It is generally believed that high myopia is an autosomal recessive inheritance, while medium and low myopia is a polygenic inheritance. The refractive power of the eye is too strong, the length of the eye axis is normal, and the curvature of the cornea and crystal surface increases, as well as the atrial water and the refractive index of the crystal increase, so that the parallel rays entering the eye form a focus before the retina, and refractive myopia is formed.