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| {{dablink|"Glasses" can also be the plural of "]".}} | |||
| {{redirect|Spectacles|other uses|Spectacle (disambiguation)}} | |||
| ] | |||
| '''Glasses''', also called '''eyeglasses''' or '''spectacles''', are frames bearing ] worn in front of the ]s, normally for ], ], or for ]. | |||
| Modern glasses are typically supported by pads on the bridge of the ] and by temples placed over the ]s. Historical types include the ], ], and ]. | |||
| Eyeglass frames are commonly made from metal or plastic. Lenses were originally made from ], but many are now made from various types of metal ], including ] and ]. These materials reduce the danger of breakage and weigh less than glass lenses. Some plastics also have more advantageous optical properties than glass, such as better transmission of ] and greater absorption of ].<ref name="polycarb">{{cite web |last=DeFranco |first=Liz |work=All About Vision |url=http://www.allaboutvision.com/lenses/polycarb.htm |title=Polycarbonate Lenses: Tough as Nails |month=April | year=2007 |accessdate=2007-09-01}}</ref> Some plastics have a greater ] than most types of glass; this is useful in the making of corrective lenses shaped to correct various ] such as ], allowing thinner lenses for a given ]. Newer plastic lenses, called izon, can also correct for the higher order aberrations that naturally occur in the surface of our eye. These lenses create sharper vision and help with the halos, starbursts, and comet-tails often associated with night time driving glare. Wavefront guided LASIK surgery also corrects for the higher order aberrations. | |||
| ] c.1805]] | |||
| Scratch-resistant coatings can be applied to most plastic lenses giving them similar scratch resistance to glass. ] coatings designed to ease cleaning are also available, as are ]s intended to reduce glare, improve night vision and make the wearer's eyes more visible.<ref name="Coatings">{{cite web |last=DeFranco |first=Liz |work=All About Vision |url=http://www.allaboutvision.com/lenses/coatings.htm |title= | |||
| Do You Need Lens Coatings? |month=May | year=2006 |accessdate=2007-09-01}}</ref> | |||
| CR-39 lenses are the most common plastic lenses due to their low weight, high scratch resistance, and low transparency for ultra violet and infrared radiation. Polycarbonate and Trivex lenses are the lightest and most shatter-resistant, making them the best for impact protection,<ref name="polycarb" /> yet offer poor optics due to high dispersion, and having a low ] of 31. | |||
| Not all glasses are designed solely for vision correction but are worn for protection, viewing visual information (such as ]) or simply just for aesthetic or fashion values. Safety glasses are a kind of ] against flying debris or against visible and near visible ] or ]. ] allow better vision in bright daylight, and may protect against damage from high levels of ]. | |||
| == History == | |||
| === Precursors === | |||
| ] | |||
| The earliest historical reference to ] dates back to ]ian ] in the 8th century BC, which depict "simple glass meniscal ]". The earliest written record of magnification dates back to the 1st century AD, when ], a tutor of Emperor ], wrote: "Letters, however small and indistinct, are seen enlarged and more clearly through a globe of glass filled with water".<ref name=Kriss>{{citation|last1=Kriss|first1=Timothy C.|last2=Kriss|first2=Vesna Martich|title=History of the Operating Microscope: From Magnifying Glass to Microneurosurgery|journal=Neurosurgery|volume=42|issue=4|pages=899-907|date=April 1998}}</ref> Emperor Nero is also said to have watched the ] using an ] as a corrective lens.<ref>{{cite web |author=Pliny the Elder |title=Natural History |url=http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+37.16 |accessdate=2008-04-27}}</ref> | |||
| Corrective lenses were said to be used by ] in the 9th century,<ref>Dr. Kasem Ajram (1992). ''Miracle of Islamic Science'', Appendix B. Knowledge House Publishers. ].</ref> who had devised a way to produce very clear glass. These glasses could be shaped and polished into round rocks used for viewing and were known as ]s. The earliest evidence of "a ], a ] forming a magnified image," dates back the '']'' published by ] in 1021. Its ] in the 12th century was instrumental to the invention of eyeglasses in 13th century ].<ref name=Kriss/> | |||
| ], in the form of flat panes of ], protected the eyes from glare and were used in ] in the ] or possibly earlier. However, they did not offer any corrective powers.<ref>{{cite web|url=http://www.ideafinder.com/history/inventions/sunglasses.htm |title=Sunglasses History - The Invention of Sunglasses |accessdate=2007-06-28 |last=Ament |first=Phil |date=2006-12-04 |work=The Great Idea Finder |publisher=Vaunt Design Group }}</ref> | |||
| === Invention of eyeglasses === | |||
| ] (1403)]] | |||
| Around 1284 in Italy, ] is credited with inventing the first wearable eye glasses.<ref>{{cite web |last=Bellis |first=Mary |title=The History of Eye Glasses or Spectacles |work=About.com:Inventors |url=http://inventors.about.com/od/gstartinventions/a/glass_3.htm |accessdate=2007-09-01}}</ref> The earliest pictorial evidence for the use of eyeglasses, however, is Tomaso da Modena's 1352 portrait of the cardinal Hugh de Provence reading in a ]. Another early example would be a depiction of eyeglasses found north of the Alpes in an altarpiece of the church of ], ], in 1403. | |||
| Many theories abound for who should be credited for the invention of traditional eyeglasses. In 1676, ], a professor of medicine at the ], wrote that he possessed a 1289 manuscript whose author complains that he would be unable to read or write were it not for the recent invention of glasses. He also produced a record of a ] given in 1305, in which the speaker, a ] monk named Fra Giordano da Rivalto, remarked that glasses had been invented less than twenty years previously, and that he had met the inventor. Based on this evidence, Redi credited another Dominican monk, Fra Alessandro da Spina of Pisa, with the re-invention of glasses after their original inventor kept them a secret, a claim contained in da Spina's obituary record.<ref>{{cite web |title= Famous Historical Statements up to 1600 |work=Antique Spectacles |url=http://www.antiquespectacles.com/statements/1600.htm |accessdate=2007-09-01}}</ref> | |||
| ]'', by the Master of ], ca. 1400-30 (]).]] | |||
| Other stories, possibly legendary, credit ] with the invention. Bacon is known to have made one of the first recorded references to the magnifying properties of lenses in 1262,<ref>{{cite web |title=....Optics Highlights: II. Spectacles |work=University of Maryland, Department of Electrical & Computer Engineering |url=http://www.ece.umd.edu/~taylor/optics2.htm |accessdate=2007-09-01}}</ref> though this was predated by ]'s '']'' in 1021.<ref name=Kriss>{{citation|last1=Kriss|first1=Timothy C.|last2=Kriss|first2=Vesna Martich|title=History of the Operating Microscope: From Magnifying Glass to Microneurosurgery|journal=Neurosurgery|volume=42|issue=4|pages=899-907|date=April 1998}}</ref> Bacon's treatise ''De iride'' ("On the Rainbow"), which was written while he was a student of ], no later than 1235, mentions using optics to "read the smallest letters at incredible distances". While the exact date and inventor may be forever disputed, it is almost certainly clear that spectacles were invented between 1280 and 1300 in Italy. | |||
| These early spectacles had ] that could correct both ] (farsightedness), and the ] that commonly develops as a symptom of ]. ] is believed to have discovered the benefits of ] in the treatment of ] (nearsightedness). However, it was not until 1604 that ] published in his treatise on ] and ], the first correct explanation as to why convex and concave lenses could correct presbyopia and myopia. | |||
| === Later developments === | |||
| ], 1580–1645]] | |||
| The ] scientist ], who suffered from both ] and ], invented ] in 1784 to avoid having to regularly switch between two pairs of glasses.<ref name="Franklin" /> The first lenses for correcting ] were constructed by the ] astronomer ] in ].<ref name="Franklin">{{cite web |last=Bellis |first=Mary |title=The Inventions and Scientific Achievements of Benjamin Franklin|url=http://inventors.about.com/od/fstartinventors/ss/Franklin_invent_4.htm|accessdate=2007-09-01}}</ref> | |||
| Over time, the construction of spectacle frames also evolved. Early eyepieces were designed to be either held in place by hand or by exerting pressure on the nose (]). ] suggested that eyepieces could be held in place by a ribbon passed over the wearer's head, this in turn secured by the weight of a ]. The modern style of glasses, held by temples passing over the ears, was developed in 1727 by the British optician ]. These designs were not immediately successful, however, and various styles with attached handles such as "]" and lorgnettes remained fashionable throughout the 18th and into the early 19th century. | |||
| In the early 20th century, ] at ] (with the assistance of H. Boegehold and A. Sonnefeld<ref>{{cite web |url=http://www.zeiss.com/C12567A100537AB9/Contents-Frame/6B49EEA709EAE719C1256919003DAE2B |title=Eyeglass Lenses and Visual Aids from Industrial Production |publisher= Zeiss.com|accessdate=2007-09-02}}</ref>), developed the Zeiss Punktal spherical point-focus lenses that dominated the eyeglass lens field for many years. | |||
| Despite the increasing popularity of ] and ] ], glasses remain very common as their technology has improved. For instance, it is now possible to purchase frames made of special ] alloys that return to their correct shape after being bent. Other frames have spring-loaded hinges. Either of these designs offers dramatically better ability to withstand the stresses of daily wear and the occasional accident. Modern frames are also often made from strong, light-weight materials such as ] alloys, which were not available in earlier times. | |||
| On ] ] the United States ] declared (section 456.2) that optometrists be required to provide the patient with a complete prescription immediately following an eye exam, effectively giving the patient the choice of where to purchase their glasses.<ref>{{cite web |title=§ 456.2 Separation of examination and dispensing |work=Federal Trade Commission |url=http://ftc.gov/bcp/rulemaking/rvalue/16cfr460.pdf |pages=453 |format=PDF |accessdate=2007-09-01}}</ref> The result was greater competition between the glasses manufacturers and thus lower prices for consumers. This trend has been accelerated by the proliferation of Internet technology, giving consumers the chance to bypass traditional distribution channels and buy glasses directly from the manufacturers.<ref>{{cite web |last=Darlin |first=Damon |title=Do-It-Yourself Eyeglass Shopping on the Internet |work=] |date=], ] |url=http://www.nytimes.com/2007/05/05/technology/05money.html?ex=1336017600&en=6b0426fd624adc46&ei=5088&partner=rssnyt&emc=rss |accessdate=2007-09-01}}</ref> | |||
| ==Types== | |||
| ===Corrective=== | |||
| ] ] as seen through a corrective lens, showing the effect of ].]] | |||
| {{main|Corrective lens|Refraction error}} | |||
| Corrective lenses modify the focal length of the eye to alleviate the effects of ], ] or ]. As people age, the eye's ] loses elasticity, resulting in ], which limits their ability to ]. | |||
| The power of a lens is generally measured in ]s. Over-the-counter reading glasses are typically rated at +1.00 to +4.00 diopters. Glasses correcting for myopia will have negative diopter strengths. Lenses made to conform to the prescription of an ] or ] are called ] and are used to make prescription glasses, which are then verified correct using a professional ]. | |||
| ===Safety=== | |||
| {{main|Eye protection}} | |||
| Safety glasses are usually made with shatter-resistant plastic lenses to protect the eye from flying debris. Although safety lenses may be constructed from a variety of materials of various impact resistance, certain standards suggest that they maintain a minimum 1 millimeter thickness at the thinnest point, regardless of material. Safety glasses can vary in the level of protection they provide. For example, those used in medicine may be expected to protect against blood splatter while safety glasses in a factory might have stronger lenses and a stronger frame with additional shields at the temples. The lenses of safety glasses can also be shaped for correction. | |||
| ] | |||
| The American National Standards Institute has established standard for safety glasses in the United States, and similar standards have been established elsewhere. | |||
| provides guidance on the type of safety eyewear that should be used for a particular application. | |||
| Some safety glasses are designed to fit over corrective glasses or sunglasses. They may provide less eye protection than ] or other forms of eye protection, but their light weight increases the likelihood that they will actually be used. Modern safety glasses tend to be given a more stylish design in order to encourage their use. Corrective glasses with plastic lenses can be used in the place of safety glasses in many environments; this is one advantage that they have over ]es. | |||
| There are also safety glasses for ], which are styled like wraparound sunglasses, but with much darker lenses, for use in welding where a full sized welding helmet is inconvenient or uncomfortable. These are often called "flash goggles", because they provide protection from welding flash. | |||
| Worker safety eyewear is available in various lens colors and/or with coatings to protect or enable eyesight in different lighting conditions, particularly when outdoors. | |||
| Nylon frames are usually used for protection eyewear for sports because of their lightweight and flexible properties. They are able to bend slightly and return to their original shape instead of breaking when pressure is applied to them. Nylon frames can become very brittle with age and they can be difficult to adjust. | |||
| ===Sunglasses=== | |||
| <!-- Unsourced image removed: ] developed coating]] --> | |||
| {{main|Sunglasses}} | |||
| Sunglasses may be made with either prescription or non-prescription lenses that are darkened to provide protection against bright ] and possibly ] light. | |||
| Glasses with ] lenses, called ]es, become darker in the presence of UV light. Unfortunately, many car windshields block the passage of UV light, making photochromic lenses less effective whilst driving on bright days. Still, they offer the convenience of not having to carry both clear glasses and sunglasses to those who frequently go indoors and outdoors during the course of a day. Recent technology has developed specialized photochromic lenses that work behind the windshield of the car, as well as outside of the car. | |||
| Light ] is an added feature that can be applied to sunglass lenses. Polarization filters remove horizontally polarized rays of light, which can cause glare. Popular among fishermen and hunters, polarized sunglasses allow wearers to see into water when normally glare or reflected light would be seen. Polarized sunglasses may present some difficulties for pilots since reflections from water and other structures often used to gauge altitude may be removed, or instrument readings on liquid crystal displays may be blocked. | |||
| Yellow lenses are commonly used by golfers and shooters for their contrast enhancement and depth perception properties. Brown lenses are also common among golfers, but cause color distortion. Blue, purple, and green lenses offer no real benefits to vision enhancement and are mainly cosmetic. Some sunglasses with interchangeable lenses have optional clear lenses to protect the eyes during low light or night time activities and a colored lens with UV protection for times where sun protection is needed. Debate exists as to whether "blue blocking" or amber tinted lenses have a protective effect. | |||
| Sunglasses are often worn just for aesthetic purposes, or simply to hide the eyes. Examples of sunglasses that were popular for these reasons include teashades and ]. | |||
| ===Special=== | |||
| ] | |||
| The ] on a two dimensional surface can be created by providing each eye with different visual information. | |||
| Classic 3D glasses create the illusion of three dimensions when viewing specially prepared images. The classic 3D glasses have one red lens and one blue lens. 3D glasses made of cardboard and plastic are distributed at ]. | |||
| Another kind of 3D glasses uses polarized filters, with one lens polarized vertically and the other horizontally, with the two images required for stereo vision polarized the same way. Polarized 3D glasses allow for color 3D, while the red-blue lenses produce a dull black-and-white picture with red and blue fringes. | |||
| One kind of electronic 3D spectacles uses electronic ]s, while ] glasses and helmets have separate video screens for each eye. | |||
| ==Variations== | |||
| Magnifying lenses which are used to treat mild ] and ], normally referred to as reading glasses, can be bought off the shelf. Most glasses are made to an individual prescription, based on degree of myopia or hyperopia combined with ] if applicable. Lenses can be ground to specific prescriptions, but in some cases standard off-the-shelf prescriptions suffice, though they require custom fitting to particular frames. | |||
| As people age, their ability to focus is lessened and many decide to use multiple-focus lenses, ] or even ] to cover all the situations in which they use their sight. Traditional multifocal lenses have two or three distinct horizontal viewing areas, each requiring a conscious effort of refocusing. Some modern multifocal lenses, such as ] (known as "no-line bifocals"), give a smooth transition between these different focal points, unnoticeable by most wearers, while other glasses have lenses specifically intended for use with computer monitors at a fixed distance. People may have several pairs of glasses, one for each task or distance, with specific glasses for reading, computer use, television watching, and writing. | |||
| ===Rimless=== | |||
| Three-piece rimless and semi-rimless glasses are common variations that differ from regular glasses in that their frames do not completely encircle the lenses. Three-piece rimless glasses have no frame around the lenses, and the bridge and temples are mounted directly onto the lenses. Semi-rimless (or half-rimless) glasses have a frame that only partially encircles the lenses (commonly the top portion), which are held in place most often by high strength nylon wire.<ref>{{cite web | |||
| |url=http://www.visioncareproducts.com/CE-old/frames_newest.html | |||
| |title=The Newest Technologies in Rimless Eyewear | |||
| |last=O’Keefe | |||
| |first=Jackie | |||
| |publisher=''Vision Care Product News'' | |||
| |date=July/August 2003 | |||
| |accessdate=2006-01-09 | |||
| }}</ref> | |||
| A rare and currently non commercial variation are rimless and frameless glasses attached to a ] at the bridge of a wearers nose.<ref>{{cite web | |||
| |url=http://www.piercedglasses.com/mark2.html | |||
| |title=Pierced Glasses | |||
| |accessdate=2007-08-07 | |||
| }}</ref> Such glasses have the visual look of the ]. | |||
| ===Glazing=== | |||
| Spectacle lenses are edged into the frame's rim using glazing machines operated by ophthalmic technicians. The edging process begins with a trace being taken of the frame's eye shape. In earlier days the trace was replicated onto a plastic pattern called a Former. Nowadays the process is patternless and the shape is sent to the edger electronically. | |||
| The lens, in the form of a round uncut, is positioned in the correct manner to match the prescription and a block is stuck to the lens and that block fits into a chuck in the edging machine. A diamond coated wheel spins as the edger replicates the frame's eye-shape to the uncut lens. A 'v' bevel is applied to allow the edge of the lens to fit into the frame rim. | |||
| ==Fashion== | |||
| ] in ].]] | |||
| Glasses can be a major part of personal expression, from the extravagance of ] and ], to ] and ]. | |||
| For some celebrities, glasses form part of their identity. United States Senator ] continued to wear lensless horn-rimmed spectacles after being fitted with contact lenses because he was not recognizable without his trademark glasses. British soap star ] had the same problem: her character on '']'', ], became so well-known for her big frames that she was expected to wear them at social gatherings and in international tours, even though Kirkbride has always worn contact lenses. ] continued to wear glasses for the same reason after getting corrective ]. ] comedic actor ], who became profoundly ] as an adult, wears glasses that contain no lenses; they are actually a bone-conducting ]. ] wears glasses to separate his professional persona as a ] from his stage persona as ] ]ese. ] wore his round-lens 'Windsor' spectacles from some of his time with the ] to his murder in 1980. The rock band ] is known for some of the members wearing thick-rimmed glasses. | |||
| ] | |||
| In ], glasses were all the disguise ] and ] needed to hide in plain view as ]s ] and ], respectively. | |||
| An example of ] is seen in the ] that those who wear glasses are intelligent or, especially in ] culture, even ]s and ]s. Some people who find that wearing glasses may look nerdy turn to contact lenses or ], especially under ]. | |||
| Another unpopular aspect of glasses is their inconvenience. Even through the creation of light frames, such as those made of ], very flexible frames, and new lens materials and ]s, glasses can still cause problems during rigorous sports. The lenses can become greasy or trap vapour when eating hot food, swimming, walking in rain or rapid temperature changes (such as walking into a warm building from cold temperatures outside), reducing visibility significantly. Scraping, fracturing, or breakage of the lenses require time-consuming and costly professional repair, though modern plastic lenses are almost indestructible and very scratch-resistant. | |||
| ] co-founder ] had a pair of eyeglasses made with lenses in the shape of the well-known Apple ]. | |||
| The lenses were made from a block of ], laminated from layers in the usual rainbow colors, and machined into the appropriate outline, with a custom-made frame in the same shape. They were made by a Silicon Valley optician. | |||
| == Disposal == | |||
| Some organizations like ]<ref>]. "" received 20 August 2008.</ref> and ]<ref>] "" received on 20 August 2008.</ref> provide a way to donate glasses and sunglasses. Unite For Sight has redistributed more than 200,000 pairs.<ref>"" '']'' 20 February 2007, received 20 August 2008.</ref> | |||
| == See also == | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| ==References== | |||
| <references/> | |||
| == External links == | |||
| {{Spoken Misplaced Pages|EN-glasses.ogg|2008-03-31}} | |||
| {{wikiquote}} | |||
| {{commons|Glasses}} | |||
| {{wiktionarypar|spectacles|glasses}} | |||
| *, extensive history and pictures of spectacles. | |||
| *, Spectacles Gallery | |||
| *, Teagle Optometry | |||
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