The main factors that determine the refractive power of the eye are the radius of curvature of the cornea, the refractive power of the lens and the length of the eye axis. The myopia caused by prolongation of the eye axis is called axial myopia. The length of the normal human eye axis is 24mm, and the refractive power increases by 3.00D for every 1mm increase in the length of the eye axis, i.e., the length of the eye axis is 25mm, which is about 300 degrees of myopia. However, the actual situation has to take into account the corneal curvature factor, and can not be inferred simply through the length of the eye axis. Myopia refers to the condition in which parallel rays of light from a distance enter the eye and focus before the retina without the use of accommodation. Myopia is an abnormal refractive state in which myopic eyes have decreased distance vision and normal near vision. The main mechanism by which eye axis lengthening occurs is related to the weakness of the sclera, especially the posterior pole sclera. The sclera is composed of fibroblasts and extracellular matrix, and a weakening of either of the two may cause ocular axis prolongation. In part, it is a genetic cause of congenital axial growth, but it may also be a biochemical substance produced by the refractive system of the eye during adjustment, causing a series of reactions that lead to myopia. The lengthening of the eye axis is an irreversible organic lesion. It is recommended to wear frame glasses or contact lenses to improve vision, and refractive surgery is also a good way to improve vision. In daily life, it is necessary to reduce close-distance study and work, to ensure reasonable eye distance, to avoid the formation of blurred images on the retina, to increase outdoor sports, to improve the lighting conditions, to slow down the occurrence of myopia and the growth of myopia.