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for adequate protection, experts recommend sunglasses that reflect or filter out 99% or more of UVA and UVB light, with wavelengths up to 400 nm.Sunglasses that meet this requirement are often labeled as "UV400".Some manufacturers already design glasses to block blue light; the insurance company Suva, which covers most Swiss employees, asked eye experts around Charlotte Remé (ETH Zürich) to develop norms for blue blocking, leading to a recommended minimum of 95% of the blue light.Sunglasses are especially important for children, as their ocular lenses are thought to transmit far more HEV light than adults (lenses "yellow" with age).a favorite affectation of thousands of women all over the U.S." It stated that 20 million sunglasses were sold in the United States in 1937, but estimated that only about 25% of American wearers needed them to protect their eyes.In the early 20th century, they were also known as sun cheaters (cheaters being an American slang term for glasses).to protect the eyes from ultraviolet radiation (UV) and blue light, which can cause several serious eye problems.
Sunglasses are not sufficient to protect the eyes against permanent harm from looking directly at the Sun, even during a solar eclipse.
At present, Xiamen, China, is the world's largest producer of sunglasses, with its port exporting 120 million pairs each year.
Various types of disposable sunglasses are dispensed to patients after receiving mydriatic eye drops during eye examinations.
The only way to assess the protection of sunglasses is to have the lenses measured, either by the manufacturer or by a properly equipped optician.
Several standards for sunglasses (see below) allow a general classification of the UV protection (but not the blue light protection), and manufacturers often indicate simply that the sunglasses meet the requirements of a specific standard rather than publish the exact figures.
The lenses of polarized sunglasses reduce glare reflected at some angles off shiny non-metallic surfaces, such as water.