Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the human eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. more...
Special glasses are used for viewing three-dimensional images or experiencing virtual reality.
Modern glasses are typically supported by pads on the bridge of the nose and by temples placed over the ears. Historical types include the pince-nez, monocle, and lorgnette.
Glasses are more often called eyeglasses in North American English, occasionally spectacles in British English, and (rarely) frames or lenses. Spectacles is often shortened to specs. In hipster slang they are cheaters.
Glasses were originally made from glass, but many are now made from plastic (often polycarbonate or CR-39) due to the danger of breakage and the greater weight of glass lenses. Some plastics also have more advantageous optical properties than glass, such as better transmission of visible light and greater absorption of ultraviolet light. Some plastics have a greater index of refraction than most types of glass; this is useful in the making of corrective lenses shaped to correct vision abnormalities such as myopia, allowing thinner lenses for a given prescription. Scratch-resistant coatings can be applied to most plastic lenses giving them similar scratch resistance to glass. Hydrophobic coatings designed to ease cleaning are also available, as are anti-reflective coatings intended to improve night vision and make the wearer's eyes more visible.
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