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by - retroglide - on February 6th, 2007

- retroglide -

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When were sunglasses invented, and are they beneficial?

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  • by canadianhelper on February 6th, 2007

    canadianhelper

    From wiki sunglasses:

    It is said that the Roman emperor Nero liked to watch gladiator fights through polished gems, likely emeralds. Sunglasses were first used in China in the 12th century or possibly earlier. The "lenses" of these glasses were flat panes of smoky quartz, which offered no corrective powers but did protect the eyes from glare. Contemporary documents describe the use of such glasses by judges in Chinese courts to conceal their facial expressions while questioning witnesses. Compare the representation of "blind Justice" in Western art.

    James Ayscough began experimenting with tinted lenses in spectacles in the mid-18th century. These were not "sunglasses" as such; Ayscough believed blue- or green-tinted glass could correct for specific vision impairments. Protection from the sun's rays was not a concern of his.

    In the early 1900's, the use of sunglasses started to become more widespread, especially among the pioneering stars of silent movies. But early movie stars did not wear sunglasses as much to avoid being recognized than to protect their eyes from the harshly bright lighting of some early film studios, often taking their sunglasses off only when stepping in front of the camera to shoot a scene.

    Protection

    Excessive exposure to ultraviolet radiation (UV) can cause short-term and long-term ocular problems such as photokeratitis, snow blindness, cataracts, pterygium, and various eye cancers.[2] Medical experts often advise the public on the importance of wearing sunglasses to protect the eyes from UV[2]. In the European Union, a CE mark identifies glasses fulfilling quality regulations. In the preparation for solar eclipses, health authorities often warn against looking at the sun through only sunglasses.

    There is no demonstrated correlation between high prices and increased UV protection. A 1995 study reported that "Expensive brands and polarizing sunglasses do not guarantee optimal UVA protection." [3] The Australian Competition and Consumer Commission has also reported that "[c]onsumers cannot rely on price as an indicator of quality" [1]. One unscientific survey even found a $6.95 pair of generic glasses with slightly better protection than Michael Kors or Salvatore Ferragamo shades [2].
    Oakley sunglasses pass the ANSI Z87.1 requirements and offer UV protection
    Oakley sunglasses pass the ANSI Z87.1 requirements and offer UV protection

    More recently, High energy visible light (HEV) has been implicated as a cause of age-related macular degeneration[4][5], and some manufacturers design to block it. Sunglasses may be especially important for children, as their ocular lenses are thought to transmit far more HEV light than adults (lenses "yellow" with age).

    Some sunglasses also pass ANSI Z87.1 requirements for basic impact and high impact protection. These are voluntary standards, so not all sunglasses comply, nor are manufacturers required to comply. In the basic impact test, a 1 in (2.54 cm) steel ball is dropped on the lens from 50 in (127 cm). In the high velocity test, a 1/4 in (6.35mm) steel ball is shot at the lens at 150 ft/s (45.72 m/s). In both tests, no part of the lens can touch the eye.

    Comments

    • I couldn't get by without my prescription sunglasses .. sensitivity to light, etc. Thanks for the great history lesson! Points + ~ wish I could rate higher!

      gone

      by gone on February 6th, 2007

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