Invention and Engineering

Glasses

Glasses, also known as eyeglasses, spectacles, or colloquially as specs, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears for support. Glasses are typically used for vision correction, such as with reading glasses and glasses used for nearsightedness; however, without the specialized lenses, they are also at times used for cosmetic purposes. Wearers may use straps tied to their glasses to prevent them from falling off. Wearers of glasses that are used only part of the time may have the glasses attached to a cord that goes around their neck to prevent the loss and breaking of the glasses. The earliest ancestors of modern eyeglasses were 13th-century Italian "reading stones". Due to the objects having no arms, wearers had to hold these magnifying spheres directly over their books. The familiar temple arms that hook over a wearer's ears were not invented until the 1700s. Safety glasses are eye protection, a form of personal protective equipment (PPE) that are worn by workers around their eyes for protection. Safety glasses act as a shield to protect the eyes from any type of foreign debris that may cause irritation or injury; these glasses may have protection on the sides of the eyes as well as in the lenses. Some types of safety glasses are used to protect against visible and near-visible light or radiation. Glasses are worn for eye protection in some sports, such as squash. Sunglasses allow for better vision in bright daylight and are used to protect one's eyes against damage from excessive levels of ultraviolet light. Typical sunglasses lenses are tinted for protection against bright light or polarized to remove glare; photochromic glasses are clear or lightly tinted in dark or indoor conditions, but turn into sunglasses when they come into contact with ultraviolet light. Most over-the-counter sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be made.

Also on this shelf

See also

• ▸LMS Coronation Class
• ▸Deertrees Theatre
• ▸Ganz Works

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