The test of myopia mainly depends on optometry, which is divided into subjective optometry and objective optometry. Usually the objective optometry is done first, that is, after the computerized optometry and photometry, the approximate myopia will be obtained, and then according to the approximate myopia, the subjective insert optometry is done, that is, the glasses are worn, the appropriate corrective lenses are inserted in the frame of the glasses, and then the best corrective visual acuity is seen, and the lowest myopia of the best corrective visual acuity is the first trial lens. After the subjective optometry, it is necessary to perform a trial fitting, which is to walk with the glasses on for 20-30 minutes to see if there is any dizziness. If there is no dizziness, the prescription will be more appropriate, that is, the current myopia, according to the myopia to prescription glasses can be.