Sunglasses or sun glasses are a form of protective eyewear designed primarily to prevent bright Sun light and high-energy visible light from damaging or discomforting the eyes. They can sometimes also function as a visual aid, as variously termed spectacles or glasses exist which feature lenses that are colored, polarized or darkened. In the early 20th century they were also known as sun cheaters (cheaters being an American slang term for glasses).

Many people find direct sunlight too bright for comfort. During outdoor activities, the human eye can receive more light than usual. Healthcare professionals recommend eye protection whenever outside to protect the eyes from ultraviolet radiation and blue light, which can cause several serious eye problems. Sunglasses have long been associated with celebrities and film actors primarily from a desire to mask their identity. Since the 1940s sunglasses have been popular as a fashion accessory, especially on the beach.

History

Precursors:

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, around 1752. 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 for him. Yellow/amber and brown-tinted spectacles were also a commonly-prescribed item for people with syphilis in the 19th and early 20th centuries because sensitivity to light was one of the symptoms of the disease. In prehistoric and historic time, Inuit peoples wore flattened walrus ivory “glasses,” looking through narrow slits to block harmful reflected rays of the sun.

Modern Developments:

In the early 1900s, the use of sunglasses started to become more widespread, especially among 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 red eyes from the powerful arc lamps 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. Polarized sunglasses first became available in 1936, when Edwin H. Land began experimenting with making lenses with his patented Polaroid filter.

Functions

Visual Clarity and Comfort:

Sunglasses can improve visual comfort and visual clarity by protecting the eye from glare. Various types of disposable sunglasses are dispensed to patients after receiving mydriatic eye drops during eye examinations. The lenses of polarized sunglasses reduce glare reflected at some angles off shiny non-metallic surfaces such as water. They are popular among fishermen because they allow wearers to see into water when normally only glare would be seen.

Protection:

Sunglasses offer protection against excessive exposure to light, including its visible and invisible components. The most widespread protection is against ultraviolet radiation (UV), which can cause short-term and long-term ocular problems such as photokeratitis, snow blindness, cataracts, pterygium, and various forms of eye cancer. Medical experts advise the public on the importance of wearing sunglasses to protect the eyes from UV; for adequate protection, experts recommend sunglasses that reflect or filter out 99-100 % of UVA and UVB light, with wavelengths up to 400 nanometers (nm). Sunglasses which meet this requirement are often labeled as “UV 400.” This is slightly less protection than the widely used standard of the European Union (see below), which requires that 95 % of the radiation up to only 380 nm must be reflected or filtered out. Sunglasses are not sufficient to protect the eyes against permanent harm from looking directly at the sun, even during a solar eclipse.

More recently, high-energy visible light (HEV) has been implicated as a cause of age-related macular degeneration; before, debates had already existed as to whether “blue blocking” or amber tinted lenses may have a protective effect. Some manufacturers already design to block blue light; the insurance company Suva, which covers most Swiss employees, asked eye experts around Charlotte Remé (ETH Zürich) to develop norms for blue blocking, leading to a recommended minimum of 95% of the blue light. Sunglasses are especially important for children, as their ocular lenses are thought to transmit far more HEV light than adults (lenses “yellow” with age). There has been some speculation that sunglasses actually promote skin cancer. This is due to the eyes being tricked into producing less melanocyte-stimulating hormone in the body.

Fashion:

Aviators:

Aviators are a sunglass design with oversized teardrop-shaped lenses and a thin metal frame. The design was introduced in 1936 by the Ray-Ban company for issue to U.S. military aviators. Their popularity with pilots, military and law enforcement personnel in the United States has never wavered.[citation needed] As a fashion statement, aviator sunglasses are often made in mirrored, colored, and wrap-around styles. In addition to pilots, Aviator-style sunglasses gained popularity with young people in the late 1960s and continue to be popular, with only a brief fall in demand during the 1990s.

Clip on Glasses:

Clip-on glasses are a form of tinted glasses that can be clipped on to eyeglasses for sun protection. An alternative are flip-up glasses.

Faded – graduated Lenses:

Faded lenses go from a darker shade at the top to a lighter one at the bottom, so there will be more protection from sunlight the higher one looks through the lens, but the lower one looks through the lens, the less protection is offered. The fashion advantage is that one can wear them indoors without fear of tripping over something and also allowing the user to see. Wearing sunglasses to nightclubs has become common in recent times, where the faded lens comes in handy. The Independent (London), has also referred to these style of sunglasses as the Murphy Lens. Double gradient lenses are dark at the top, light in the middle and dark at the bottom.

Flip-up Glasses:

Flip-up glasses combine sunglasses and corrective glasses, allowing the wearer to flip up the tinted lenses for indoor use. An alternative are clip-on glasses.

Mirror shades:

The Mirrorshades

Mirrorshades are sunglasses with a mirrored coating on the surface. Mirrored lenses are an alternative to polarization for UV protection, improving contrast when depth perception is important such as seeing moguls and ice while skiing or snowboarding. The mirrored lens reflects glare to protect the eyes but improves the ability to see contrasts, and mirrored lenses of different colors can expand the range of fashion styles. Their popularity with police officers in the United States has earned them the nickname “cop shades”. The two most popular styles are dual lenses set in metal frames (which are often confused with Aviators, see above) and “Wraparounds” (see below).

Oversized sunglasses

Oversized sunglasses, which were fashionable in the 1980s, are now often used for humorous purposes. They usually come in bright colors with colored lenses and can be purchased cheaply. The singer Elton John sometimes wore oversized sunglasses on stage in the mid-1970s as part of his Captain Fantastic act. In the early twenty-first century moderately oversized sunglasses have become a fashion trend. There are many variations, such as the ‘Onassis’, discussed below, and Dior white sunglasses. 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 in the 1960s. The glasses continue to be popular with women, and celebrities may use them, ostensibly to hide from paparazzi. Oversized sunglasses also offer more protection from sunburn to the larger areas of skin they cover, although sunblock should still be used.

Shutter Shades

Shutter Shades were a fad in the early 1980s. Instead of tinted lenses, they decrease sun exposure by means of a set of parallel, horizontal shutters (like a small window shutter). Analogous to Inuit goggles (see above), the principle is not to filter light, but to decrease the amount of sun rays falling into the wearer’s eyes. To provide UV protection, Shutter Shades sometimes use lenses in addition to the shutters; if not, they provide very insufficient protection against ultraviolet radiation and blue light.

Teashades:

The Teashade

‘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 1960s drug counterculture, as well as by opponents of segregation.[citation needed] Rock stars such as Mick Jagger, Roger Daltrey, John Lennon, Jerry Garcia, Liam Gallagher and Ozzy Osbourne, 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 1960s, they were often elaborated: lenses were elaborately colored, mirrored, and degregated, produced in excessively large sizes, and with the wire earpieces exaggerated. A uniquely-colored or darkened glass lens was usually preferred. Modern versions tend to have plastic lenses, as do many other sunglasses. Teashades are hard to find in shops today; however, they can still be found at many costume websites and in some countries.

The term has now fallen into disuse, although references can still be found in literature of the time. ‘Teashades’ was also 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). The glasses worn by Seraph in the Matrix films are teashades. Teashades are briefly referenced during a police training seminar in Hunter S. Thompson’s novel Fear and Loathing in Las Vegas. Anime characters Ban Mido (GetBackers) and Basara Nekki (Macross 7) are almost never seen without their purple-lensed teashades. Vash the Stampede (Trigun) wears yellow-lens teashades. Main character of Hellsing, Alucard, wears red-lensed teashades. Recently, actress and fashion icon Mary-Kate Olsen and pop music singer Lady Gaga have been seen wearing several variations of teashades. Howard Stern was also known for wearing teashades in the early to mid 90’s and never taking them off in public.

Wayfarers

The Ran Ban Wayfarer

The Ray-Ban Wayfarer is a plastic-framed design for sunglasses produced by the Ray-Ban company. Introduced in 1952, the trapezoidal lenses are wider at the top than the bottom and were famously worn by James Dean and other actors. The original frames were black; frames in many different colours were later introduced.

Wraparounds

Wraparounds are a specific design of sunglasses. They are characterized by a single, smooth, semi-circular lens that covers both eyes and much of the same area of the face covered by protective goggles. The lens is usually combined with a minimal plastic frame and single piece of plastic serving as a nosepiece. As an alternative, the glasses can have two lenses, but the design evokes the same semicircle. Wraparound sunglasses are also quite popular in the world of extreme sports.

Courtesy of Wikipedia Free Encyclopedia http://en.wikipedia.org/wiki/Sunglasses.