Myopia can be classified into three classes according to the degree of myopia: 1. 300 degrees or less, called mild myopia. 2. moderate myopia, which refers to myopia between 325 and 600 degrees. 3. over 600 degrees or more, called high myopia. The criteria for this classification are usually intended to show the degree of damage to the eye caused by the degree of myopia. Mild and moderate myopia are usually physiological in nature and do not cause more pathological manifestations other than a loss of distance vision. High myopia, on the other hand, is also known as pathological myopia, which not only causes loss of distance vision, but also results in high myopic fundus changes, such as retinal pigment disorders, high myopic retinopathy, and in severe cases, even macular cleavage, macular hemorrhage, retinal detachment, retinal fissures, etc.