Eyes should also be protected from sun! Teach you three steps to choose the right sunglasses.

The sunshine in summer is getting stronger and stronger. Besides skin protection, don't forget to protect your eyes from the sun! In daily visible light, there are high-energy ultraviolet rays, which can be divided into UVA, UVB and UVC according to different wavelengths. The ozone layer can block most of UVB and UVC, and UVA has a long wavelength and strong penetration, which is still available in our daily life. UVA may cause eyelid malignant tumor, photokeratitis and other diseases. Fortunately, the cornea and lens of the eye also have isolation effect, and only about 1.5% really enters the retina, but long-term accumulation may also cause macular degeneration.

So how to choose sunglasses to protect your eyes? Here are three steps to teach you to choose the right sunglasses.

Step 1: Select the lens marked with UV400. The so-called UV400 can filter ultraviolet rays below 400nm wavelength and block 99% to 100% ultraviolet rays. This technology is quite popular at present, and shops selling sunglasses generally have instruments to detect ultraviolet rays, which can help lens detection.

Step 2: Choose lenses of different colors as needed, which has different visual experience and applicability. Many people have a misconception about sunglasses that the darker the color, the better, but this is not the case. Choose the most suitable one according to your own use situation.

Blue-gray lens: suitable for water sports and seaside wear. Because it is a neutral lens, it can evenly absorb the spectrum of various colors, effectively reduce the light intensity and effectively remove the light blue reflected by seawater and sky. Brown lens: It is suitable for daytime driving or foggy conditions, because it can filter out a lot of blue light, adjust contrast and clarity, and has the advantage of blocking reflected light. Yellow lens: suitable for indoor and night activities and foggy, dusk, rainy and other environments. It absorbs the strongest blue light and is the most commonly used color for athletes. Can effectively block blue light, enhance contrast, bright and not dazzling. Orange lens: suitable for indoor and night activities, outdoor with weak sunshine. With the same function as the yellow lens, the blue light absorption effect is strong and the contrast effect is stronger. Red lens: it can only block short-wavelength light and has no protective effect. This is a popular ornament. Gray lens: suitable for all kinds of activities, because it belongs to neutral color system, so as to evenly absorb the spectrum of various colors, effectively reduce the light intensity, and there will be no obvious color difference. Step 3: Select the lens transmittance according to the requirements. The stronger the sunlight or the longer the use time, the lower the light transmittance will be. According to the domestic CNS specification, the filter is divided into 0 to 4 grades, and the standard sunglasses will be labeled with the filter grade of glasses.

Grade 0: the penetration rate is 80–100%, suitable for night and evening use. Grade 1: the penetration rate is 43-80%, which is suitable for cloudy and cloudy weather. Grade 2: penetration rate18–43%, suitable for general daytime use. Grade 3: the penetration rate is 8–18%, which is suitable for strong sunlight and water activities. Grade 4: the penetration rate is 3-8%, which is suitable for use in snow. Generally, lenses with light transmittance greater than 40% are more fashionable than those without UV400 labels. It is best to choose a light transmittance of 8-40%, which is suitable for most cases. As for the fourth grade, the light transmittance is only 3-8%, which is not suitable for driving. Usually used in strong light environment, such as mountaineering and skiing.

Generally speaking, you can choose gray lenses and sunglasses with light transmittance of 8-40%, which are suitable for most situations. In addition, anti-blue glasses can't replace sunglasses, because blue light and ultraviolet light have different positions in the spectrum, and anti-blue glasses have no inspection standards, so the efficacy can't be confirmed.