We have all learned about spectroscopy in high school physics. Simply put, the wavelength range of visible light we see is 380-780nm. For this part of light, the function of sunglasses is to reduce the transmission of light and reduce the strong light that the eyes receive in summer. For the wavelength range of 100-380nm that we cannot see, namely ultraviolet radiation, its impact on our eyes is actually much greater than the strong sunlight. For the eyes, prolonged exposure to ultraviolet radiation can easily lead to various eye diseases, and some may even experience symptoms such as eye pain, photophobia, decreased vision, and corneal edema in a short period of time. So in summer, a pair of sunglasses is needed to block strong light and ultraviolet rays.
UV protection is an essential function of sunglasses, which is not related to the color and transparency of the lenses. It is generally achieved through coating, and is usually expressed in the following three ways:
1. Sunglasses labeled with "UV400": This indicates that the lens can block ultraviolet and visible light with wavelengths below 400nm; As long as the ultraviolet light passing through the lens is less than 2%, it is considered qualified;
2. Sunglasses labeled with "UV" and "UV protection": This indicates that the lens can block ultraviolet rays below 380nm; As long as the ultraviolet light passing through the lens is less than 2%, it is considered qualified;
3. Sunglasses labeled with "100% UV absorption": This indicates that the lens has a 100% absorption function for ultraviolet rays; But in fact, if the ultraviolet light passing through the lens is less than 0.5%, it is considered qualified.
When choosing UV resistant sunglasses without considering other factors, you can follow the above three points to purchase. Moreover, in general, eyewear tags will indicate this. Sunglasses are not just cool and handsome accessories, they are also a special tool to protect the eyes from harm, especially a good helper for travel and driving.
