If you wear glasses to produce dizziness, eye swelling and other discomfort, do not think that after a period of time will adapt, it is likely that your glasses are not qualified. A pair of unqualified glasses will not only fail to correct and protect your vision, but will also cause new refractive errors. So, how to match a pair of qualified glasses? 1, glasses should be based on the regular hospital prescription. Optometry methods are divided into two categories, namely objective optometry (dilated optometry) and subjective optometry. Pupil dilatation optometry: children and adolescents or farsighted patients, because the eye muscle regulation function is too strong and must be used to adjust the paralyzing agent, after the pupil dilatation, to understand the true refractive state and refractive error. However, for refractive errors over 40 years of age, especially those with a tendency to glaucoma, it is recommended that dilated pupils not be used for optometry to avoid glaucoma. Subjective optometry: Refractive examinations performed by the patient’s subjective perception alone are subjective optometry. The results of this type of optometry can vary somewhat from the actual situation, with myopic eyes being more likely to be high and farsighted eyes being less likely to be high than they actually are. Commonly used subjective optometry are small pupil check shadow method, cloud method, insert method, etc. In developed countries, optometry must be medically trained and qualified by the relevant state departments to carry out. And some optometry practitioners in China have lower quality. In order to make up for the technical deficiencies, some opticians are equipped with computerized optometry machines. This optometry can quickly give refractive data, but the refractive data provided by the computer and the refractive error of the examined eye has a certain gap, which is particularly prominent in adolescents. Because the computer currently cannot exclude the adjustment function of the human eye, the resulting data may be overcorrected for myopia and undercorrected for hyperopia. Therefore, adolescents should first go to a regular hospital medical optometry. 2, measuring the pupil distance. The optical center of the lens must be in the center of the wearer’s pupil, the optical center of the lens has no deviation, including horizontal deviation, vertical deviation, is also a major indicator of the quality of glasses. When the distance between the optical centers of the lenses is smaller than the actual pupil distance, the eyes have to use the collection function too much, which will promote the development of myopia. If the lens optical center spacing is greater than the actual pupil spacing or optical center up and down shift, vision will appear eye swelling, headache and other visual fatigue symptoms, resulting in the new glasses can not be used. This is also the reason why you cannot blindly choose large frames. Because the human eye is not adjustable in the upper and lower side, so even if the optical center of the lens is accurate, the vertical optical center of the left and right lens is misaligned, which will cause the patient to wear the lens discomfort. The deviation of the vertical optical center of the left and right spectacle lenses that the human eye can tolerate is 0.125cm on average and should not exceed 0.25cm. 3. The diopter of the lenses fitted should be the same as the diopter on the optometry sheet. If the deviation exceeds the national standard, it will accelerate the development of myopia or hyperopia. If you have astigmatism, the axial position of the column lens should be the same as the axial position on the prescription, if it exceeds the national standard (the error should be within 5 degrees), it will cause new astigmatism. 4, the lens transmission should be good. If there is a defect in the center of the lens, it will affect the transmittance of the lens and bring dark shadows. In addition, the thicker and heavier the color of the varicose lenses, the more it will affect the transmission of the lenses. Therefore, it is recommended that people with moderate refractive error or more do not match color-changing lenses. 5, the distance between the glasses and the eyes and the various angles of the glasses frame should be adjusted appropriately.