Explore Inventors Biography Alphabetically

 

Home A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 
Techsciencenews Home 
 
 
 

Art | Business Studies | Citizenship | Countries | Design and Technology | Everyday life | Geography | History | Information Technology | Language and Literature | Mathematics | Music | People | Portals | Religion | Science | Timeline of Inventions | Subject Index

 

Sunglasses

Wearing sunglasses under direct sunlight

Sunglasses or sun glasses are forms of protective eyewear that usually enclose or protect the eye pupil in order to prevent strong light and uv rays from penetrating. 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).[1]

Many people find direct sunlight too bright to be comfortable. 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, which can cause several serious eye problems. Sunglasses have long been associated with celebrities and film actors primarily from a desire to hide or mask their identity. Since the 1940s sunglasses have been popular as a fashion accessory, especially on the beach.

Contents

History

United States Secret Service agents wearing sunglasses

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.[2] 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.[3]

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 of his.

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

In prehistoric and historic time, Inuit peoples wore flattened walrus ivory "glasses," seeing through narrow slits, in order to block the harmful reflected rays of the sun.[4][5]

Modern developments

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 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.

Uses

Paul Newman wearing sunglasses

Hiding one's eyes has implications in face-to-face communication: It can hide weeping, being one of the signs of mourning, makes eye contact impossible which can be intimidating, or can show detachment, which is considered cool in some circles. Darkened sunglasses of particular shapes may be in vogue as a fashion accessory. Normal glasses are very rarely worn without a practical purpose. The impact on nonverbal communication and the cool image are among the reasons for wearing sunglasses at night or indoors. People may also wear sunglasses to hide dilated or contracted pupils or bloodshot eyes (which would reveal drug use), recent physical abuse (such as a black eye), or to compensate for increased photosensitivity. Fashion trends are another reason for wearing sunglasses, particularly designer sunglasses.

John Major at Newlands Cricket Ground wearing sunglasses, January 2000.

People with severe visual impairment, such as the blind, often wear sunglasses in order to avoid making others uncomfortable—hidden eyes may be better than seeing eyes which seem to look in the wrong direction. Those whose eyes have an abnormal appearance (for example due to cataract) or which jerk uncontrollably (nystagmus) may also do so.

Visual clarity and comfort

Sunglasses can improve visual comfort and visual clarity by protecting the eye from glare.[6]

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 glare or reflected light would be seen

Protection

Sunglasses should pass the ANSI Z87.1 requirements and offer UV 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 forms of eye cancer.[7] Medical experts often advise the public on the importance of wearing sunglasses to protect the eyes from UV[7]. In the European Union, a CE mark identifies glasses fulfilling quality regulations. Sunglasses are not sufficient to protect the eyes against permanent harm from looking directly at the sun, even during a solar eclipse.

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." [8] The Australian Competition and Consumer Commission has also reported that "[c]onsumers cannot rely on price as an indicator of quality".[9] One survey cited below even found a $6.95 pair of generic glasses with slightly better protection than Salvatore Ferragamo shades.[10]

More recently, high-energy visible light (HEV) has been implicated as a cause of age-related macular degeneration[11][12], 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.

British singer Paul King, 1986

There has been some speculation that sunglasses actually promote skin cancer.[13] This is due to the eyes being tricked into producing less melanocyte-stimulating hormone in the body.

Standards

There are three sunglass standards.[14]

The Australian Standard is AS 1067. The five sunglass ratings under this standard are based on the amount of light they absorb, 0 to 4, with “0” providing some protection from UV radiation and sunglare, and “4” a high level of protection.

The UK standard is ANSI Z80.3-1972. According to the ANSI Z80.3-2101 standard, the lens should have a UVB (280 to 315 nm) transmittance of no more than one per cent and a UVA (315 to 380 nm) transmittance of no more than 0.3 times of the visual light transmittance

The European standard, EN 1836:2005, has four ratings: "0" for insufficient UV protection, "2" for sufficient UHV protection, "6" for good UHV protection and "7" for full UHVV protection.

Water sunglasses

Water sunglasses, also known as surfing sunglasses, surf goggles and water eyewear consist of eyewear specially adapted to be used in turbulent water, such as the surf. Features normally available include
a) shatterproof and impact-resistant lenses
b) strap or other fixing to keep glasses in place during sporting activities
c) buoyancy to stop them from sinking should they come off
d) nose cushion
e) vent or other method to eliminate fogging

These sunglasses are used in water sports such as surfing, windsurfing, kiteboarding, wakeboarding, kayaking, jet sking, Bodyboarding, and water skiing.

Construction

Lens

The color of the lens can vary by style, fashion, and purpose, but for general use, red, grey, yellow, or brown is recommended to avoid or minimize color distortion which would be perfectly safe when, for instance, driving a car, or a school bus.

  • Gray lenses are considered neutral because they enhance bright colors.
  • Brown and green lenses cause some severe color distortion, but have contrast-limiting properties.
  • Turquoise lenses are good for medium and higher light conditions because they are good at enhancing contrast, but do not cause significant color distortion.
  • Orange and yellow lenses have the worst contrast enhancement at depth perception but minimalize color distortion. Yellow lenses are used by fishers and shooters for their contrast enhancement and width perception properties.
  • Blue or purple lenses are mainly cosmetic.

With the introduction of office computing, ergonomists can recommend mildly tinted glasses for display operators to increase contrast.

Clear lenses are used typically to protect the eyes from impact, debris, dust, or chemicals. Some sunglasses with interchangeable lens have wet lenses to protect the eyes during low light or early morning activities. Debates exist as to whether "blue blocking" or amber tinted lenses may have a protective effect.[15] Blue blocking sunglasses typically never block any light or other colors to function well in dim sunlight. Low blue glasses are sometimes recommended to treat insomnia by being worn in artificial lighting after dark, to reestablish the circadian rhythm. They allow enough light so normal evening activities can continue, while blocking the light that prevents production of the hormone melatonin.

Some models have polarized lenses, made of Polaroid polarized plastic sheet, to reduce glare caused by light reflected from polarizing surfaces such as water (see Brewster's angle for how this works) as well as by polarized diffuse sky radiation (skylight). This can be especially useful when fishing, as the ability to see beneath the surface of the water is crucial.

A mirrored coating can also be applied to the lens. This mirrored coating reflects some of the light when it hits the lens before it is transmitted through the lens making it useful in bright conditions. These mirrored coatings can be made any color by the manufacturer for styling and fashion purposes. The color of the mirrored surface is irrelevant to the color of the lens. For example, a gray lens can have a blue mirror coating, and a brown lens can have a silver coating. Sunglasses of this type are sometimes called mirrorshades. A mirror does not get hot in the sunlight and prevents scattering in the lens bulk.

Sunglass lenses are made from either glass or plastic. Plastic lenses are typically made from acrylic, polycarbonate, CR-39 or Polyurethane. Glass lenses have the best optical clarity and scratch resistance, but are heavier than plastic lenses. They can also shatter or break on impact. Plastic lenses are lighter but are more prone to scratching. Plastic offers more resistance to shattering than glass. Polycarbonate plastic lenses are the lightest, and are also almost shatterproof, making them good for impact protection. CR-39 is the most common plastic lens, due to their low weight, high scratch resistance, and low transparency for ultraviolet and infrared radiation.

Any of the above features: color, polarization, gradation, mirroring, and materials can be combined into the lens for a pair of sunglasses. Gradated glasses are darker at the top of the lens where the sky is viewed and transparent at the bottom. Corrective lenses or glasses can be manufactured with either tinting or darkened to serve as sunglasses. An alternative is to use the corrective glasses with a secondary lenses such as oversize sunglasses that fit over the regular glasses, clip-on lens that are placed in front of the glasses, and flip-up glasses which feature a dark lens that can be flipped up when not in use. Photochromic lens gradually darken in bright light.

Frames

This sunglass-eyeshield uses a nylon half-frame and interchangeable lenses

Frames are generally made from plastic, nylon, a metal or metal alloy. Nylon frames are usually used in sports because they are light weight and flexible. They are able to bend slightly and return to their original shape instead of breaking when pressure is applied to them. This flex can also help the glasses grip better on the wearer's face. Metal frames are usually more rigid than nylon frames thus they can be more easily damaged when participating in sporty activities, but this is not to say that they cannot be used for such activities. Because metal frames are more rigid, some models have spring loaded hinges to help them grip the wearer's face better. The end of the resting hook and the bridge over the nose can be textured or have a rubber or plastic material to hold better. The end of the resting hook are usually curved so that they wrap around the ear; however, some models have straight resting hooks. Oakley, for example, has straight resting hooks on all their glasses, preferring to call them "earstems".

Frames can be made to hold the lenses in several different ways. There are three common styles: full frame, half frame, and frameless. Full frame glasses have the frame go all around the lenses. Half frames go around only half the lens, typically the frames attach to the top of the lenses and on the side near the top. Frameless glasses have no frame around the lenses and the ear stems are attached directly to the lenses. There are two styles of frameless glasses: those that have a piece of frame material connecting the two lenses together, and those that are a single lens with ear stems on each side.

Some sports-oriented sunglasses have interchangeable lens options. Lenses can be easily removed and swapped with a different lens, usually a different coloured lens. The purpose of this is to allow the wearer to easily change lenses when light conditions or activities change. The reason for this is because the cost of a set of lenses is less than the cost of a separate pair of glasses and carrying extra lenses is less bulky than carrying multiple pairs of glasses. It also allows easy replacement of a set of lenses if they are damaged. The most common type of sunglasses with interchangeable lenses have a single lens or shield that covers both eyes. Styles that use two lenses also exist, but are less common.

Nose bridge

Nose bridges allow support between the lens and the face. Nose bridges also prevent pressure marks caused by the weight of the lens or frame on the cheeks. People with large noses may need a low nose bridge on their sunglasses. People with medium noses may need a low or medium nose bridge. People with small noses may need sunglasses with high nose bridges to allow clearance.

Fashion

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 twentyfirst 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.

Mirrorshades

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 nosepiece). Wraparound sunglasses are also quite popular in the world of extreme sports.

Aviators

Aviator sunglasses

Aviators are sunglasses with an oversized teardrop-shaped lens and thin metal frames. The design was introduced 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, 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 continued to be very popular with only a brief fall in demand during the 1990s.

Wayfarers

The plastic-framed Ray-Ban Wayfarer design with trapezoidal lenses wider at the top than the bottom worn by James Dean and other actors was introduced in 1952. The original frames were black; frames in many different colours were later introduced.

Teashades

Teashade sunglasses

'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. 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 rare to find in shops today however can be found at many costume websites and different countries.

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).

In fiction, the glasses worn by Seraph in the Matrix films are teashades. 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.

Recently, actress and fashion icon Mary-Kate Olsen and pop music sensation Lady Gaga have been seen wearing several variations of teashades.

Flip-up glasses

Flip-up glasses are a form of eyeglasses that allow the wearer to flip up a sunglasses layer up for indoor use. The alternative is clip-ons. Dwayne Wayne, a character on the television program A Different World was known for wearing flip-up glasses.[16]

Glacier glasses

Sometimes called glacier goggles: sunglasses with leather blinders at the sides that protect the eyes by blocking the sun's rays around the edges of the lenses. Typically, these have very dark round lenses. Because they provide extra protection from bright sun and light reflected by snow and ice, they are often used when mountain climbing, or traveling across glaciers or snowfields.

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 you look on the lens but the farther one looks down the less protection one gets. The fashion advantage is that one can wear them inside and not fear 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.[17] Double gradient lenses are dark at the top, light in the middle and dark at the bottom.

Shutter shades

Instead of having lenses, the design is characterized by its "shutter" motif, which is part of the frame.

Other names for sunglasses

There are also various words referring to eyepieces with darkened lenses:

  • Shades is probably the most widely used term for sunglasses in North America.
  • Glares is a term popular in India if the glass is dark. If it is light then Coolers.
  • Sun spectacles is a term used by some opticians.
  • Spekkies is a term used predominantly in southern Australia.
  • Sun specs (also sunspecs) is the shortened form of sun spectacles.
  • Sunglass a monocle version.
  • Sun-shades can also refer to the sun-shading eyepiece-type, although the term is not exclusive to these. Also in use is the derivative abbreviation, shades.
  • Dark glasses (also preceded by pair of) - generic term in common usage.
  • Sunnies is Australian, UK and New Zealand Slang
  • Specs is a common name for sunglasses in North America, and for spectacles elsewhere.
A man wearing sunglasses
  • Smoked spectacles usually refers to the darkened eyepieces worn by blind people.
  • Solar Shields Usually refers to the models of sunglasses with large lenses.
  • Stunna shades Used as a slang term in the hyphy movement, usually referring to sunglasses with oversized lenses.
  • Locs (also maddoggers) is a brand of sunglasses worn by rappers, gangsters and cholos.
  • Bono's This refers to the lead singer in U2 often seen wearing sunglasses.
  • Glecks is Scottish slang for glasses or sunglasses.
  • Cheaters
  • Tints

In Indonesia, people refer them as kaca mata hitam which means literally 'black glasses'.

Legality and security concerns

Sunglasses, particularly oversized ones, are capable of hiding face features, including eye colour, from security guards, security apparatus such as CCTV cameras, and police officers. For this reason, in situations where security is emphasized, people who wear sunglasses may draw attention from security personnel or be asked to remove them when indoors or when walking near street protests.

There are two recent examples of sunglasses-related security limitations, both in Greece after the 2008 Greek riots:

  • Various Greek banks including the National Bank of Greece, as of 2009 (after increased incidents of violence and robberies), in some of their branches ask customers to remove sunglasses when entering the bank premises. Such notices are put up on the branch doors. The same applies to helmets as well.
  • The government of Greece made a law (sometimes called the koukoulonomos) that makes it illegal to wear hoods or hide one's face features in any way while participating in violent street protests. The penalty for hiding one's face features during riots is 2 to 10 years in prison. Since sunglasses can hide one's face features, they can be considered illegal apparatus when violent protesters wear them, just as hoods are. The same applies to helmets as well.

Major Brands

Major Retailers

See also

  • Goggles
  • Polaroid Eyewear

Notes and references

External links