Eyeglasses should be made of optical glass, optical resin and other materials, which have good uniformity, stable refractive index, high transmission rate, and can intercept the harmful ultraviolet rays to the eyes. Consumers should not be greedy for cheap and buy glasses made of ordinary glass. Many teenagers suffer from vision loss due to homework tension, watching TV or playing too many games. When this happens, it could be pseudomyopia or true myopia. If it is pseudomyopia, there is no need to wear glasses and the symptoms will be eliminated after a period of rest. Once pseudomyopia is put on glasses, it becomes true myopia and is difficult to recover from. In order to avoid misdiagnosis, it is best to see a doctor to determine if glasses are needed after a dilated eye exam. For children with amblyopia and strabismus diagnosed by a doctor, they should cooperate with the treatment and not wear glasses blindly or without glasses. Don’t believe in the “computerized optometry, get it right away” sign. A pair of qualified glasses has to go through multiple processes such as optometry, frame selection, lens fitting, testing, processing and fitting, shaping and re-testing, which can hardly be completed within half a day. The selection of frames and lenses must be based on optometric prescriptions, scientific and reasonable, and should be compatible with your face shape. After wearing the qualified glasses should have clear vision, no strong discomfort, no symptoms such as dizziness, nausea, rising eyes and tilted vision. Patients with high myopia (more than -4.00D) should consider choosing lenses with high refractive index (around 1.7); patients with low myopia can choose lenses with low refractive index. Optical glass lenses are inexpensive and have a strong surface resistance to wear; resin lenses are light and generally block ultraviolet rays; coated, hardened and treated ultra-thin resin lenses are more expensive. It should be reminded that the production and use of glass lenses is now mandatory because they are fragile and easy to scratch the eyes. Patients with presbyopia should not be blindly fitted with glasses, because there is a possibility that the eye disease may cause the eyes. When you get a pair of glasses, you have to follow the regular procedures of optometry and prescription, don’t just buy a pair of adult lenses and wear them. The impact of ultraviolet light on the human body is a growing concern, wearing sunglasses is one of the better ways to protect the eyes from ultraviolet damage. A pair of qualified sunglasses, not only can decorate the appearance, but also can block ultraviolet light through, and no diopter, the different colors of the traffic signal has good discrimination. Consumers buy sunglasses; do not only pay attention to novel styles and distinctive enzyme style, to have a sense of self-protection, especially after wearing sunglasses dizziness, nausea, shaking eyes and other discomfort, must not be reluctant to wear, so as not to be harmed. The following is a simple identification of the advantages and disadvantages of glasses and real or fake: qualified metal frames, good surface finish, no scratches, two mirror rims of the same size, the parts of fine workmanship, fine welding points. Quality plastic frame should be soft in the hard, feel moderate strength. Regular manufacturers of eyeglass frames are with specifications, size, brand name and other words. Lenses made of ordinary glass, side observation more green, this glass transmittance is low, the material is not uniform, containing more impurities, stripes, bubbles, etc., mostly flat convex or flat concave type. Lens surface shape should be regular, should not appear spiral and Huo light, etc.. Identification method is to hold the frame in front of the hands, the lens convex outward, slowly moving up and down, from the lens to observe distant objects, if most of the object is stationary, but local ripple-like beating phenomenon, the lens surface is not flat, there is Huo light. Sunglasses are flat lenses, should not come with top focus degree. After wearing if there is dizziness, nausea and other uncomfortable symptoms, should be aware of the lens appears top focus degree. When the edges of flat lenses are not equally thick, they can be shifted after wearing them. Explanation: Top focus – is the name of a unit of measure used to express the size of a lens’ ability to bend light, numerically equal to the reciprocal of the lens’ focal length in meters. F represents the focal length, F represents the top focal length that is F = 1/f. The top focal length is expressed as the reciprocal of the unit of meters (m-1), and the unit name is diopter, the symbol is “D”. For example, a spherical lens can be expressed as -2.00DS, which can correct 200 degrees of myopia, and +3.00DC, which can correct 300 degrees of farsightedness. If the top focal length is greater than the refractive power of the eye, wearing glasses will cause new refractive errors in excess of the refractive power. If the top focal length is less than the refractive power of the eye, the refractive error cannot be completely corrected. The deviation of the top focal length of the eyeglass lenses in the prescription glasses must comply with GB10810.1-2005 “eyeglass lenses” standard requirements. Some people like to wear crystal glasses to show the status of noble, in fact, the optical properties of crystal lenses is far from high-quality optical glass, consumers are advised not to wear. Consumers match glasses, it is best to have access to the production license of the formal store to buy, to obtain invoices and repair, replacement, refund of the voucher. If you encounter quality problems, you can go to the consumer association or technical supervision department to solve.