First observe whether the lens has scratches, impurities, bubbles and stripes, and check the outer packaging of sunglasses. Regular sunglasses should be marked with product name, color, diameter, quality grade, manufacturer's name and trademark. Sunglasses with anti-UVA, UVB and CE signs on the mirror or tag can guarantee to block some ultraviolet rays. Second, try wearing sunglasses to see if you feel dizzy or have a headache. At present, there are some myopia sunglasses with degrees on the market, but because the pupil distance and other indicators vary from person to person, consumers had better not choose these sunglasses with degrees without professional guidance. Third, point the two corners of the sunglasses in your hand at the fluorescent lamp and let the reflective strip of the mirror roll gently. If you find that the shadow of the fluorescent lamp reflected by the mirror is wavy and twisted, it proves that the lens is uneven, and such a mirror will damage your vision. Fourth, the lens should be flat and transparent. The materials of sunglasses are glass and resin, and the best sunglasses should be polarized lenses. It is made of light and precise synthetic resin like contact lenses, and consists of seven thin layers, the outermost two of which are superhard wear-resistant layers; The second layer and the sixth layer are shatterproof reinforcement layers; The third and fifth layers are ultraviolet filter layers, and the middle layer is polarization filter layer. Polarized lenses can effectively filter reflected light and harmful ultraviolet rays, and have the functions of shatterproof and wear resistance, so they are the most popular sunglasses. Fifth, the color of sunglasses should be matched according to skin color, face shape and wearing, and should also be selected according to the place of entry and exit. Generally speaking, black, brown and gray have good filtering effect; Gray lenses can absorb any color spectrum evenly, and the scenery you see after wearing them will only darken without obvious color difference; Brown lenses can filter out a lot of blue light and improve visual contrast and clarity, especially when the air pollution is serious or foggy. Sixth, what shades of sunglasses are suitable for us? The simple self-test method is to put on sunglasses in front of the mirror and let yourself see your pupils vaguely. If the color is too light, the filtering effect is too small; If the color is too dark, it will affect the vision and weaken the color sense. Colorful and light-colored sunglasses, which are popular this year, should not be used in seaside water activities, snow with strong reflection or strong sunshine, but should be worn with sports sunglasses, mostly colorful and saturated, which can absorb or reflect more visible light. Seventh, in addition to reducing the strong light stimulation and making eyes comfortable, the main purpose of wearing sunglasses is to prevent ultraviolet rays from hurting eyes. The color of the lens and whether it protects against ultraviolet rays are two different things. Even if the lens is dark, it may not be able to effectively resist ultraviolet rays. So be sure to choose lenses marked with anti-ultraviolet function. Usually the UV index of sunglasses is between 96% and 98%. Eighth, general optical shops will have instruments to test the anti-ultraviolet ability of sunglasses. Through this test, you can know whether the glasses in your hand are helpful to eye health, and see whether the glasses company has obtained the production license of glasses products. Second, see if the optometry equipment and testing instruments of the glasses enterprises have qualified marks; Third, see if optometrists and producers have certificates; Fourth, see if the glasses are qualified. The four certificates of glasses enterprises are the premise to ensure the quality of glasses. Accurate optometry. Consumers had better choose hospitals or larger optical shops for optometry. Choose the right frames and lenses. Consumers should choose different styles of frames according to their age and professional characteristics; Because everyone's face, pupil distance and diopter are different, the size of the frame varies from person to person; Lenses are divided into glass sheets and resin sheets, and consumers can choose according to their own preferences. At present, the lens materials used are divided into: glass lens; Resin lens; PC lens; Among them, the glass lens has stable refractive index, good wear resistance and stable optical performance, but it is heavy and easy to break. Glass lens: stable refractive index, good wear resistance and stable optical performance, but it is heavy and easy to break. Resin lens (CR-39): light, safe, high transmittance, not easy to break, but the surface is easy to wear. PC lens: high refractive index and high strength, but the surface is easy to wear. Wearing glasses is still recognized as the safest way to correct ametropia. But the quality of glasses directly affects the correction effect. A pair of unqualified glasses will cause the wearer's visual fatigue, aggravate the visual decline, and even cause headache, dizziness, nausea, indigestion and listlessness in severe cases. Teenagers, in particular, are in the developmental stage, and they will regret wearing inferior glasses for life. The author has been engaged in the quality inspection of glasses products for many years, and now I will talk about my experience and experience in the purchase of glasses products for consumers' reference. Glasses should be made of optical glass, optical resin and other materials with good uniformity, stable refractive index and high transmittance, which can intercept ultraviolet rays harmful to eyes. Consumers should not buy glasses made of ordinary glass for the sake of cheapness. Many teenagers have poor eyesight because of intense homework, watching TV or playing games too much. This condition may be pseudomyopia or true myopia. If it is pseudomyopia, you don't need to wear glasses, and the symptoms will be eliminated after a period of rest. Once pseudomyopia is put on glasses, it will become true myopia, and it is difficult to recover. In order to avoid misdiagnosis, it is best to find a doctor to determine whether to wear glasses after mydriasis optometry. Children with amblyopia and strabismus diagnosed by doctors should cooperate with the treatment, not blindly or without glasses. Don't trust computer optometry, wait for the sign of satisfaction. A pair of qualified glasses must go through many processes, such as optometry, frame selection, glasses fitting, testing, processing and fitting, plastic surgery, re-inspection and so on. And it is difficult to finish it in half a day. The choice of frames and lenses must be based on optometry prescription, scientific and reasonable, and should be suitable for your face. After wearing qualified glasses, you should see things clearly, without strong discomfort, and you should not have dizziness, nausea, eyeball swelling, tilt and other symptoms. Patients with high myopia (above 4.00D) should consider choosing lenses with high refractive index (about 1.7); Patients with low myopia can choose lenses with low refractive index. Optical glass lenses have low price and strong surface wear resistance; Resin lenses are light in weight and can generally block ultraviolet rays; The price of ultra-thin resin lens after coating hardening treatment is higher.