Sunglasses

It is said that the Roman emperor Nero liked to watch gladiator fights with emeralds. These, however, appear to have worked rather like mirrors.Flat panes of smoky quartz which offered no corrective powers but did protect the eyes from glare were used in China in the 12th century or possibly earlier. Contemporary documents describe the use of such crystals by judges in Chinese courts to conceal their facial expressions while questioning witnesses.

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.
Yellow/Amber and brown-tinted spectacles were also a commonly-prescribed item for people with syphillis in the 19th and early 20th centuries because of the sensitivity to light that was one of the symptoms of the disease.

In the early 1900s, the use of sunglasses started to become more widespread, especially among the pioneering stars of silent movies. It is commonly believed that this was to avoid recognition by fans, but the real reason was they often had perennially sore eyes from the powerful arc lights that were needed due to the extremely slow speed film stocks used. The stereotype persisted long after improvements in film quality and the introduction of ultraviolet filters had eliminated this problem. Inexpensive mass-produced sunglasses were introduced to America by Sam Foster in 1929. Foster found a ready market on the beaches of Atlantic City, New Jersey, where he began selling sunglasses under the name Foster Grant from a Woolworth on the Boardwalk.

Sunglasses first became polarized in 1936, when Edwin H. Land began experimenting with making lenses with his patented Polaroid filter.
Onassis glasses or "Jackie O's" are very large sunglasses worn by women. This style of sunglasses is said to mimic the kind most famously worn by Jacqueline Kennedy Onassis. While originally worn by Onassis in the 1960's, the glasses eventually became popular with younger American girls around the year 2003. Big sunglasses have maintained their popularity through 2007. They have also expanded their demographic reach to adult women throughout the world. Modern day celebrities use these to hide from paparazzi.

Mirrorshades are sunglasses with a mirrored coating on the surface. Their popularity with police officers in the United States has earned them the nickname "cop shades". The two most popular styles for these are dual lenses set in metal frames (which are often confused with Aviators), and "Wraparound" (a single, smooth, semi-circular lens that covers both eyes and much of the same area of the face covered by protective goggles, combined with a minimal plastic frame and single piece of plastic serving as a nosepick). Wraparound sunglasses are also quite popular in the world of extreme sports.

Aviators are sunglasses with an oversized teardrop-shaped lens and thin metal frames. This design first appeared in 1936 by Ray Ban for issue to U.S. military aviators. Their popularity with pilots, military and law enforcement personnel in the United States has never wavered. As a fashion statement, models of aviator sunglasses are often made in mirrored, colored, degregated, and wrap-around styles. In addition to pilots, Aviator-style sunglasses gained popularity with young people in the late 1960's and continued to be very popular through the 70's and early 80's.

First introduced by Ray-Ban, the Wayfarer design popularized since the 1950s by Hollywood celebrities such as James Dean is thought to be the bestselling sunglasses design to date['Teashades' (sometimes also called '"John Lennon glasses" or "Ozzy Glasses", after Ozzy Osbourne') were a type of Psychedelic art wire-rim sunglasses that were often worn, usually for purely aesthetic reasons, by members of the 60's drug counterculture, as well as by opponents of segregation. Rockstars such as Mick Jagger, John Lennon, Ozzy Osbourne, and Janis Joplin all wore teashades. The original teashade design was made up of medium-sized, perfectly round lenses, supported by pads on the bridge of the nose and a thin wire frame. When teashades became popular in the late 1960's, they were often elaborated; lenses were elaborately colored, mirrored, and degregated, and often of excessively large size, and the wire earpieces were sometimes exaggerated. A uniquely-colored or darkened glass lens was usually preferred.

The term has now fallen into disuse, although references can still be found in literature of the time. Teashades are briefly referenced during a police training seminar in Hunter S. Thompson's Fear and Loathing in Las Vegas. 'Teashades' also was used to describe glasses worn to hide the effects of marijuana (conjunctival injection) or 'bloodshot' eyes or the effects of opiates such as heroin (pupillary constriction).

Source : en.wikipedia.org/wiki/Sunglasses