0.2 refers to the visual acuity, that is, the measurement of the visual acuity table, the visual acuity of the naked eye is 0.2. 0.2 does not indicate how many degrees of myopia, the specific check how many degrees of myopia, the need for computerized optometry and other optometric methods to determine the degree, so 0.2 visual acuity and how many degrees there is no corresponding relationship, let’s say that three people may have 0.2 vision, but it is possible that the number of degrees of these three people, the first person is 200 degrees, the second person is 300 degrees, the third person is 400 degrees of myopia. The first person is 200 degrees, the second person is 300 degrees, the third person is 400 degrees of myopia, which is possible. The specific 0.2 is how many degrees of myopia need optometry to determine, 0.2 vision is relatively low, if found to be due to myopia causes, must be corrected by wearing glasses or contact lenses.