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Standard sunglasses are unable to filter out eye-damaging radiation. Solar viewers can be used for safe viewing of solar events such as eclipses . The recommended optical density of this eyewear is 5, meaning that the solar viewing filter only permits 1 part in 100,000 of incident light to pass through.
Inuit snow goggles function by reducing exposure to sunlight, not by reducing its intensity. Since the 13th century and until the spread of contemporary UV-shielding spectacles against snowblindness, Inuit made and wore snow goggles of flattened walrus or caribou ivory with narrow slits to look through to block almost all of the harmful reflected rays of the sun.
A photochromic lens is an optical lens that darkens on exposure to light of sufficiently high frequency, most commonly ultraviolet (UV) radiation. In the absence of activating light, the lenses return to their clear state. Photochromic lenses may be made of polycarbonate, or another plastic. Glass lenses use visible light to darken.
Polycarbonate is lighter weight than normal plastic. It blocks UV rays, is shatter resistant, and is used in sports glasses and glasses for children and teenagers. Because polycarbonate is soft and will scratch easily, a scratch-resistant coating is typically applied after shaping and polishing the lens.
Photokeratitis can be prevented by using sunglasses or eye protection that transmits 5–10% of visible light and absorbs almost all UV rays. Additionally, these glasses should have large lenses and side shields to avoid incidental light exposure. Sunglasses should always be worn, even when the sky is overcast, as UV rays can pass through ...
Fighter pilot helmet includes a visor for protection from the sun and from wind blast in case of an ejection from the aircraft. Some firefighter's helmets have visors which protect the eyes from infrared rays and the radiant heat of fire as well as from impact. Hockey helmets have visors, shields, cages and masks to protect the eyes and face ...