UV protection: The main function of sunglasses is to protect the eyes. And eye tissues through the filtering of ultraviolet rays in the sun. The large mirror of sunglasses can also play a role in protecting the skin around the eyes.
Sunshade protection: Sunglasses generally have a certain color. They can block a certain amount of sunlight, avoid glare, reduce temperature, and prevent sun burns.
Special protection: For people who wear contact lenses, the reasonable wearing of sunglasses can prevent or reduce the excessive evaporation of water in some contact lenses. And extend the comfort of wearing contact lenses in summer.
Classification by use (QB 2457-1999 industry mandatory standard):
Light-colored sunglasses: the first category of the corresponding transmittance. The ability to block the light is weak. But the color is rich, suitable for a variety of occasions, clothing collocation and personal modeling decoration.
For the second and third categories of transmission, which is our most common sunglasses category. The ability to block the sun is excellent, which can effectively reduce the stimulation of light on the human eye.
Special purpose sunglasses: for the transmittance of the fourth category of products, has a very strong light protection. And commonly used in beaches, skiing and mountaineering and other outdoor activities with strong light.
How to choose a sunglass?
Look at the sign. According to industry standards, all sunglasses on sale must be hung with relevant signs. Moreover, the sign should be marked with the implementation standard number, such as QB2456, GB10180, etc. That indicate the first few categories of products, such as sunshade mirrors, special purposes, etc. At the same time, it is necessary to indicate the manufacturer, trademark, material, etc. To facilitate the buyer to purchase correctly according to the demand.
Look at the category logo. Different categories of sunglasses should be used in different scenarios, the category is not used, and the purpose is different. For example, category 1 products or light-colored sunglasses are more suitable for fashion collocation, not suitable for blocking the light. And 4 types of products are more suitable for outdoor sports. Conventional use is not appropriate, such as driving, the light is too dark. In addition, many sunglasses at the same time have a polarizing function, generally marked polarizing. If there is a need for fishing, driving, etc., you can look for products with polarizing functions.
Look at the UV protection ability For sunglasses, the most important thing is to be able to protect the eyes from ultraviolet rays. There is usually a small sticker on the frame, indicating UV protection. For example, when you choose sunglasses, see marked “UV400,” that the product of the UV cutoff wavelength of 400 nm. And the maximum value of transmission is not more than 2%; If the product is labeled “UV” or “anti-UV,” then the UV cutoff wavelength of the lens is 380 nm. And the maximum value of the transmittance is not more than 2%; If labeled “100% UV,” it means that the lens has 100% absorptive capacity to UV. And the maximum value of transmittance is not more than 0.5%. If there is no special indication of the UV protection ability. As long as it belongs to the classification recognized by the GB10180.3-2006 national standard or QB2457-1999 industry standard. It has sufficient ultraviolet protection ability.
Look at the lens color In general, although we need sunglasses to prevent light damage. But this does not mean that the darker the better, or the heavier the color, the better. On the color depth, you can check whether it is appropriate through self-identification. If you bring your own sunglasses, but also can clearly see their eyes. Then the color is too light, not suitable for long-term outdoor use. If you can’t see your eyes clearly and the surrounding color changes at the same time. It means that the lens color is too deep and weakens the color sense. Which will affect the safety of driving outside and is not suitable for wearing all day for a long time. In the choice of sunglasses, gray, brown, green gray, these three colors due to the absorption of the spectrum. It will not cause a large color difference, while improving visual contrast and other advantages. Generally can be used as a preferred target.
Look at the lenses Although now qualified products generally will not appear before those problems. Such as: on both sides of the lens have color difference. There are holes on the lens, bubbles, ripples, defective spots and other problems. However, there may still be slight differences in luminosity, excessive installation stress resulting in deformation of objects, and distortion of objects resulting in dizziness. Therefore, when selecting sunglasses, you can take it in your hand to observe the straight lamp tube through the lens. The straight outline of the building moves slowly, and observe whether there are surging, bending and other phenomena.