Ultraviolet rays are solar rays with wavelengths between 200nm and 380nm, including three types: UVA wavelengths of 315nm to 380nm, UVB wavelengths of 280nm to 315nm, and UVC wavelengths of 200nm to 280nm. 13% of the solar rays (290nm to 2000nm) that reach the earth’s surface are ultraviolet rays, of which UVA accounts for 97%, UVB accounts for 3%, and UVC is close to zero. UV damage to the human eye is mainly determined by the wavelength, radiation time and radiation intensity of UV and the strength of the eye’s own defense mechanism, the cornea and lens are the most commonly damaged eye tissue by UV, and solar keratitis and corneal endothelial damage, solar cataract are the most relevant eye diseases. Studies have found that nearly 30% of solar radiation penetrates the atmosphere, especially UV rays with wavelengths greater than 315nm are the most damaging to the eyes: 1. Long-term exposure of the eyes to the hot sun can cause corneal injury called acute UV corneal epitheliitis (also known as electrophthalmia), and affected children can experience eye pain, blurred vision, tearing and other irritating symptoms. 2, long-term exposure of the eyes to UV radiation will affect the lens metabolism, resulting in a decrease in crystal light transmission and an earlier age of cataract onset, affecting vision. 3.Once the retinal macula is damaged by UV light, it is irreversible and will lead to macular degenerative disease, which will seriously affect vision. Therefore, it is still necessary to wear sunglasses for children to protect them from the sun in summer under the sun exposure. Theoretically, children should wear sunglasses. However, children under the age of 6 should not wear sunglasses for long periods of time because their visual function is not yet mature and they need more bright light and clear objects to stimulate them. If they wear sunglasses for a long time, the macular area of the eyes will not be effectively stimulated, which will affect the further development of vision and may even lead to amblyopia in serious cases. First of all, take your child to a regular hospital for vision and intraocular examination as soon as possible, and at the same time, find a professional lens maker to check whether the sunglasses have UV protection, and check whether the glasses have astigmatism or other degrees. The most common problem is amblyopia in young children, because the child is young, vision is still in the developmental stage, long-term wearing glasses too dark light affects the visual development, or lenses have astigmatism and other degrees, artificially brought refractive error, also affect the visual development. In addition, even if the lens does not have the degree, if long-term wear poor quality sunglasses without UV protection, darker light, the pupil is dilated, long-term bright light stimulation will lead to intraocular and fundus lesions. If you have any of the above problems, remove the lenses immediately, have a professional dilated pupil examination for optometry and early amblyopia training, and for fundus lesions, you need early retinal neuroprotection and nutritional therapy to prevent further deterioration of vision. To prevent amblyopia, the correct method is to put them on your child when the sun is strong and remove them promptly when the sun becomes weak. If you must buy sunglasses for your child, choose polarized lenses, which are colored in gray or teal, which absorb almost 100% of ultraviolet and infrared rays; and the soft tint makes the vision comfortable and makes the eyes less fatigued. They cause the least color distortion, the best color perception and the best imaging. Gray lenses can be balanced absorption of any color spectrum, the scene seen after wearing the lenses will only darken without significant chromatic aberration; teal lenses can filter out a lot of blue light, can improve visual contrast and clarity, especially in the case of serious air pollution or foggy wear. Red and yellow sunglasses lenses are better at blocking light at some shorter wavelengths, while other protective effects are lower than the former. Blue light is the main cause of retinal macular degeneration, choose sunglasses, blue lenses not only can not block the blue, indigo, purple three visible light, but also will attract these harmful blue light through the eye, the worst effect of eye protection. You should try to avoid choosing blue lenses. Black color is too dark, blocking too much light, the child’s visual environment is too dark, it will delay the time of the eyes to send images to the visual center of the brain, for small children easy to lead to amblyopia, while the child is easy to cause danger when moving. How to identify the advantages and disadvantages: 1, when buying sunglasses, to observe whether its lenses have scratches, impurities, bubbles, stripes, etc.; secondly, to check the outer packaging of sunglasses products, because the general packaging box for its products will have the name, color, quality level, production plant name and trademark, the degree of UV protection, polarized or not, such as anti-counterfeiting signs. Whether a pair of sunglasses have anti-UV function, we can not discern with the naked eye, the factory’s express commitment to the product is the only reference for consumers to buy sunglasses with protective function, we can see in some product labels and glasses front such as: “100% UV protection”, ” UV400″, “block all the ultraviolet rays”, “UV protection” and other express signs. 2, when buying sunglasses, it is best to try on to see how the visual effect, ask the child whether there is vertigo, headaches and other feelings, to exclude the lens has the degree or pupil distance is not suitable for the reason. So be sure to choose the regular [brand optical store or hospital children’s professional eyeglasses center to buy, professional optometrist or mirror maker will be through the means of testing to give the child to choose the right sunglasses for him. Children can wear sunglasses, but it should be noted that children under 6 years old are not suitable to wear sunglasses for a long time. Because their visual function development has not reached the adult level, long time wearing sunglasses may form amblyopia.