Visual acuity is usually the result of a vision test using a standard logarithmic visual acuity chart. The most commonly used visual acuity chart in China is the standard logarithmic visual acuity chart, and the results of the visual acuity test are usually recorded by the five-point recording method. 400 degrees of myopia can be tested with a visual acuity chart with a result of 4.6 at best and 4.0 at worst, but the result of 400 degrees of myopia is not derived from the visual acuity chart alone, there is no accurate conversion formula between the result of the visual acuity chart and the degree of myopia, and the result of the visual acuity chart test does not directly reflect the degree of myopia. The results of the vision chart test do not directly reflect the degree of myopia. Myopia detection requires a combination of visual acuity testing, eye health examination, and initial visual function examination to determine the degree of myopia. The visual acuity checklist is only a simple check of visual acuity, but it is also necessary to check the refractive state of the eye by examining the changes in the light reflected from the lens, and to check the degree of astigmatism. The process of vision check may also be affected by many factors such as the professionalism of the inspector, the light of the test site, the testing equipment, the astigmatism of the person being examined, etc. There is also the possibility of pseudomyopia in the process of growth and development of adolescents, and pupils generally need to be dilated during the first optometry to exclude pseudomyopia. Therefore, the results of the vision chart examination cannot directly reflect the state of myopia, let alone directly determine the degree of myopia.