Myopia, or nearsightedness, refers to a refractive condition where, in a relaxed state of accommodation, parallel light rays are focused in front of the retina after passing through the eye's refractive system. Myopia is categorized by degree into mild myopia, which is less than or equal to 300 degrees, moderate myopia ranging from 325 to 600 degrees, and high myopia, which is over 600 degrees. Generally, the degree of myopia is within 600 degrees, and most patients do not exhibit any pathological changes in the fundus. They require the use of suitable concave lenses for correction. If the degree of myopia exceeds 600 degrees, a fundus examination is necessary. If there are no special changes in the fundus, correction can also be made using appropriate concave lenses.