Glasses

A pair of eyeglasses

Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the human eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. Special glasses are used for viewing three-dimensional images or experiencing virtual reality.

Modern glasses are typically supported by pads on the bridge of the nose and by temples placed over the ears. Historical types include the pince nez, monocle, and lorgnette.

Glasses are more often called eyeglasses in North American English, occasionally spectacles in British English, and (rarely) frames or lenses. Spectacles is often shortened to specs. In hipster slang they are cheaters.

Glasses were originally made from glass, but many are now made from plastic (often polycarbonate or CR-39) due to the danger of breakage and the greater weight of glass lenses. Some plastics also have more advantageous optical properties than glass, such as better transmission of visible light and greater absorption of ultraviolet light. Some plastics have a greater index of refraction than most types of glass, allowing thinner lenses for a given prescription. Scratch-resistant coatings can be applied to most plastic lenses giving them similar scratch resistance to glass. Hydrophobic coatings designed to ease cleaning are also available, as are anti-reflective coatings intended to improve night vision and make the wearer's eyes more visible.

Corrective spectacles have lenses shaped to correct vision abnormalities, such as myopia.

Safety glasses are a kind of eye protection against flying debris or visible and near visible light or radiation.

Sunglasses protect against high levels of visible and ultraviolet light.

History

Detail of a portrait of Hugh de Provence, painted by Tomasso da Modena in 1352

Glasses were possibly invented in northern Italy, most likely in the late 1280s. The identity of the original inventor is unknown, although a possible source is the Arabs, who may have had magnifying lenses in the 10th century. In 1676, Franciscus Redi, a professor of medicine at the University of Pisa, 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, and a record of a sermon given in 1305, in which the speaker, a Dominican 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. In 1738, a Florentine historian named Domenico Manni reported that a tombstone in Florence credited one Salvino d'Armato (died 1317) with the invention of glasses. Other stories, possibly legendary, credit Roger Bacon with the invention. Bacon's published writings describe the magnifying glass (which he did not invent), but make no mention of glasses.

These early spectacles had convex lenses that could correct the farsightedness (presbyopia) that commonly develops as a symptom of aging. Nicholas of Cusa is believed to have discovered the benefits of concave lens in the treatment of myopia (nearsightedness). However, it was not until 1604 that Johannes Kepler published in his treatise on optics and astronomy, the first correct explanation as to why convex and concave lenses could correct presbyopia and myopia. The American scientist Benjamin Franklin, who suffered from both myopia and presbyopia, invented bifocals in 1784 to avoid having to regularly switch between two pairs of glasses. The first lenses for correcting astigmatism were constructed by the British astronomer George Airy in 1827.

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 (pince-nez). Girolamo Savonarola 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 hat. The modern style of glasses, held by temples passing over the ears, was developed in 1727 by the British optician Edward Scarlett. These designs were not immediately successful, however, and various styles with attached handles such as scissors glasses and lorgnettes remained fashionable throughout the 18th and into the early 19th century.

Despite the increasing popularity of contact lenses and laser corrective eye surgery, glasses remain very common and their technology has not stood still. For instance, it is now possible to purchase frames made of special memory metal 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.

Corrective glasses

Corrective lenses modify the focal length of the eye to alleviate the effects of shortsightedness (myopia), longsightedness (hyperopia) or astigmatism. The power of a lens is generally measured in diopters. Over-the-counter reading glasses are typically rated at +1.00 to +3.00 diopters. Glasses correcting for myopia will have negative diopter strengths. Lenses made to conform to the prescription of an ophthalmologist or optometrist are called prescription lenses and are used to make prescription glasses.

Safety glasses

Safety glasses with side shields Wraparound safety glasses

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 that vary in impact resistance, certain standards suggest that they maintain a minimum 1mm thickness at the thinest 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. Some safety glasses are designed to fit over corrective glasses or sunglasses. They may provide less eye protection than goggles, face shields or other forms of eye protection, but their light weight increases the likelihood that they will actually be used. Recent safety glasses have tended to be given a more stylish design, in order to encourage their use. The pictured wraparound safety glasses are evidence of this style change with the close fitting nature of the wraparound dispensing with the need for side shields.

Corrective glasses with plastic lenses can often be used in the place of safety glasses in many environments; this is one advantage that they have over contact lenses.

Sunglasses

Scratch-resistant sunglasses made using a NASA developed coating

Main article: Sunglasses

Sunglasses may be made with either prescription or non-prescription (i.e. plano) lenses that are darkened to provide protection against bright visible light. Good sunglasses should also protect against ultraviolet light. Due to changes in the atmosphere, ultraviolet levels are much higher than in the past and ultraviolet protection for eyes and skin is even more important. It is possible to have lenses that look very dark and yet offer little ultraviolet protection. Sunglasses vary greatly and many offer more style than protection.

Glasses with photosensitive lenses, called photochromic lenses, become darker in the presence of UV light. Unfortunately, many car windshields protect the passengers from UV light, while not shielding from bright visible light, making photochromic lenses ineffective where they are most needed. 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.

Light polarization is an added feature that can be applied to sunglass lenses. Polarization filters remove horizontal 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 in that reflections from water and other structures often used to gauge altitude may be removed, or instrument readings on liquid crystal displays may be blocked.

Special glasses

The illusion of three dimensions 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 3D movies. Another kind of 3D glasses uses polarized filters. One kind of electronic 3D spectacles uses electronic shutters.

Virtual reality glasses and helmets have separate video screens for each eye and a method for determining the direction the head is turned.

Conditions glasses are used to correct

Glasses fitted with corrective lenses are a common means of correcting focus problems such as myopia (nearsightedness, short-sightedness) and hyperopia (farsightedness, long-sightedness). Emmetropia, the condition of ideal focus is described as two parallel rays of light entering the eye and converging on or at the retina. Myopia is a condition in which parallel rays of light entering the eye converge before reaching to retina. Hyperopia is a condition in which parallel rays of light entering the eye do not converge prior to reaching the retina. Some would say "the rays of light converge at an imaginary point behind the retina." Astigmatism is a condition in which parallel rays of light entering the eye converge at two separate locations, either before and/or after the retina. As most people age the crystalline lens of the eye loses elasticity resulting in presbyopia, which limits their ability to focus on nearby objects. None of these conditions is considered a disease.

Variation in glasses

Glasses can be very simple. Magnifying lenses for reading that are used to treat mild hypermetropia and presbyopia can be bought off the shelf, but most glasses are made to a particular prescription, based on degree of myopia or hypermetropia combined with astigmatism. Lenses can be ground to specific eyes, but in most cases standard off-the-shelf prescriptions suffice, but require custom-fitting to particular frames.

As people age, their ability to focus is lessened and many decide to use multiple-focus lenses, bifocal or even trifocal to cover all the situations in which they use their sight. Traditional multifocal lenses have two or three distinct viewing areas, each requiring a conscious effort of refocusing. These were originally separate lenses, as invented by Benjamin Franklin. Some modern multifocal lenses give a smooth transition between these lenses, unnoticeable by most wearers. Others have lenses specifically intended for use with computer monitors at a fixed distance. Many people have several pairs of glasses, one for each task or distance, with specific glasses for reading, computer use, and television watching.

Glasses as a fashion accessory

Buddy Holly's thick-rimmed glasses were part of his all-American image.

Glasses are often regarded as unattractive, and many people prefer to wear contact lenses for that reason. Contact lenses also provide much improved peripheral vision.

On the other hand, many people are attracted to people who wear glasses, and glasses are available in a wide range of styles, materials, and even designer labels.

Glasses can be a major part of personal expression, from the extravagance of Elton John and Dame Edna Everage, from Groucho Marx to John Denver to Lisa Loeb all the way to the varied professional personas of eyeglass-wearing knowledge workers.

For some celebrities, glasses form part of their identity. American Senator Barry Goldwater 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 Anne Kirkbride had the same problem: her character on Coronation Street, Deirdre Barlow, 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. Drew Carey continued to wear glasses for the same reason after getting corrective laser eye surgery. British comedic actor Eric Sykes, who became profoundly deaf as an adult, wears glasses that contain no lenses, but are in fact a bone-conducting hearing aid. Masaharu Morimoto wears glasses to separate his professional persona as a chef from his stage persona as Iron Chef Japanese. And of course John Lennon wore his round "granny glasses" from some of his time with the Beatles to his assassination in 1980.

In popular culture, glasses were all the disguise Superman and Wonder Woman needed to hide in plain view as alter egos Clark Kent and Diana Prince, respectively.

An example of halo effect is seen in the stereotype that those who wear glasses are intelligent or, especially in teen culture, even geeks and nerds. This conception probably comes from an era when most people were illiterate and the first people to wear glasses were those who did a lot of reading. Some people who find that wearing glasses may look nerdy turn to contact lenses instead, especially under peer pressure.

Another unpopular aspect of glasses is their inconvenience. Even though the late-20th century saw the creation of light frames, such as those made of titanium, very flexible frames, and new lens materials and optical coatings, glasses can still cause problems during rigorous sports. The lenses themselves can also become greasy or trap vapour when eating hot food or swimming or walking in rain, 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.

Other names for glasses

  • Pair of glasses (or just glasses) is commonly used in Britain and in North America. Compare with other meanings of the word glass.
  • Spectacles is widely used in Britain and occasionally in the US, in addition to use by professional opticians. Also in frequent use is the shortened form, specs.
  • Eye glasses or eyeglasses is a word used in North American English. In contrast, glass eye refers to a cosmetic prosthetic artificial eye that replaces a missing eye.
  • Frames is sometimes used to refer to framed eyepieces, although it is not common.
  • Lenses is also sometimes used to refer to framed eyepieces, although it is not common.
  • Cheaters is used in the hipster argot. Eyeglasses were a common part of the hipster persona, for example Dizzy Gillespie.

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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. In India, the word may also refer to a restaurant, since earlier the best restaurants were always situated next to a good hotel. The lenses themselves can also become greasy or trap vapour when eating hot food or swimming or walking in rain, reducing visibility significantly. In Australia, the word "hotel" often refers to a public house, a drinking establishment which does not necessarily provide accommodations. Even though the late-20th century saw the creation of light frames, such as those made of titanium, very flexible frames, and new lens materials and optical coatings, glasses can still cause problems during rigorous sports. Examples:. Another unpopular aspect of glasses is their inconvenience. Hotels also feature in films , television series, songs and even theme park rides.

Some people who find that wearing glasses may look nerdy turn to contact lenses instead, especially under peer pressure. It is especially true of crime fiction, farces, and mysteries. This conception probably comes from an era when most people were illiterate and the first people to wear glasses were those who did a lot of reading. They are perfect for mysterious, anonymous settings where multiple characters may gather in equal positions. An example of halo effect is seen in the stereotype that those who wear glasses are intelligent or, especially in teen culture, even geeks and nerds. Hotels have often been chosen by authors as the setting of their literary works. In popular culture, glasses were all the disguise Superman and Wonder Woman needed to hide in plain view as alter egos Clark Kent and Diana Prince, respectively. It opened in 717 CE, and features hot springs.

And of course John Lennon wore his round "granny glasses" from some of his time with the Beatles to his assassination in 1980. According to the Guinness Book of World Records, the oldest hotel still in operation is the Hoshi Ryokan, in Awazu, Japan. Masaharu Morimoto wears glasses to separate his professional persona as a chef from his stage persona as Iron Chef Japanese. According to About.com, 8 of the top 10 largest hotels are in Las Vegas. British comedic actor Eric Sykes, who became profoundly deaf as an adult, wears glasses that contain no lenses, but are in fact a bone-conducting hearing aid. Third place belongs to the Luxor Hotel, also in Las Vegas, with 4,408 rooms. Drew Carey continued to wear glasses for the same reason after getting corrective laser eye surgery. The largest single-building hotel is the MGM Grand Las Vegas in Las Vegas, Nevada, with 5,005 rooms.

British soap star Anne Kirkbride had the same problem: her character on Coronation Street, Deirdre Barlow, 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. In 2000, the First World Hotel, in Genting Highlands, Malaysia, claimed that it was in the process of developing a 6,300-room hotel complex; however, it appears that only about 3,000 rooms have been built and opened to the public. American Senator Barry Goldwater continued to wear lensless horn-rimmed spectacles after being fitted with contact lenses because he was not recognizable without his trademark glasses. It is a resort complex with a number of buildings, but the exact room count has not been independently verified. For some celebrities, glasses form part of their identity. The largest hotel in the world is the Ambassador City Jomtien resort, in Jomtien, near Pattaya, Thailand, at 5,100 rooms. Glasses can be a major part of personal expression, from the extravagance of Elton John and Dame Edna Everage, from Groucho Marx to John Denver to Lisa Loeb all the way to the varied professional personas of eyeglass-wearing knowledge workers. However, this title may be taken by the less illustrious Ryugyong Hotel in Pyongyang at 330 meters (1,083 feet), pending its (perhaps unlikely) completion; it has been under construction since 1987 and was abandoned in 1992.

On the other hand, many people are attracted to people who wear glasses, and glasses are available in a wide range of styles, materials, and even designer labels. The tallest hotel in the world is the Burj al-Arab in Dubai, at 321 meters (1,053 feet). Contact lenses also provide much improved peripheral vision.
. Glasses are often regarded as unattractive, and many people prefer to wear contact lenses for that reason. The Library Hotel in New York City is unique in that its ten floors are arranged according to the Dewey Decimal System. Many people have several pairs of glasses, one for each task or distance, with specific glasses for reading, computer use, and television watching. Its architecture will feature two domes that break the surface and an underwater train tunnel, all made of transparent materials such as glass and acrylic.

Others have lenses specifically intended for use with computer monitors at a fixed distance. Hydropolis is an ambitious project to build a luxury hotel in Dubai, UAE, with 220 suites, all on the bottom of the Persian Gulf, 20 meters (66 feet) below the surface. Some modern multifocal lenses give a smooth transition between these lenses, unnoticeable by most wearers. It only has one room, however, and Jules' Undersea Lodge in Key Largo, Florida, which requires scuba diving, is not much bigger. These were originally separate lenses, as invented by Benjamin Franklin. As of 2005, the only hotel with an underwater room that can be reached without Scuba diving is Utter Inn in Lake Mälaren, Sweden. Traditional multifocal lenses have two or three distinct viewing areas, each requiring a conscious effort of refocusing. Ice hotels, such as the canonical Ice Hotel in Jukkasjärvi, Sweden, melt every spring and are rebuilt out of ice and snow every winter.

As people age, their ability to focus is lessened and many decide to use multiple-focus lenses, bifocal or even trifocal to cover all the situations in which they use their sight. Main article: Ice hotel. Lenses can be ground to specific eyes, but in most cases standard off-the-shelf prescriptions suffice, but require custom-fitting to particular frames. Desert Cave Hotel in Coober Pedy, South Australia and the Cuevas Pedro Antonio de Alarcón (named after the author) in Guadix, Spain, as well as several hotels in Cappadocia, Turkey, are notable for being built into natural cave formations, some with rooms underground. Magnifying lenses for reading that are used to treat mild hypermetropia and presbyopia can be bought off the shelf, but most glasses are made to a particular prescription, based on degree of myopia or hypermetropia combined with astigmatism. Bill Gates even invested and had a suite built there with satellite internet/phone. Glasses can be very simple. The Ariau Towers near Manaus, Brazil is a well-known hotel, in the middle of the Amazon, on the Rio Negro.

None of these conditions is considered a disease. Some hotels, such as the Costa Rica Tree House in the Gandoca-Manzanillo Wildlife Refuge, Costa Rica, or Treetops Hotel in Aberdares National Park, Kenya, are built with living trees as structural elements, making them treehouses. As most people age the crystalline lens of the eye loses elasticity resulting in presbyopia, which limits their ability to focus on nearby objects. The Burj Al Arab in Dubai, held to be the most luxurious in the world, also merits a mention. Some would say "the rays of light converge at an imaginary point behind the retina." Astigmatism is a condition in which parallel rays of light entering the eye converge at two separate locations, either before and/or after the retina. Other such establishments include the Beverly Hills Hotel and the Chateau Marmont, both in in California, USA. Hyperopia is a condition in which parallel rays of light entering the eye do not converge prior to reaching the retina. Hotels that enter popular folklore like these two are also often frequented by celebrities, as is the case both with the Ritz and the Chelsea.

Myopia is a condition in which parallel rays of light entering the eye converge before reaching to retina. A number of hotels have entered the public concsiousness through popular culture, such as the Ritz Hotel in London, UK ('Putting on The Ritz') and Hotel Chelsea in New York City, subject of a number of songs and also the scene of the alleged stabbing of Nancy Spungen by her boyfriend Sid Vicious. Emmetropia, the condition of ideal focus is described as two parallel rays of light entering the eye and converging on or at the retina. Another example is the Hotel Sacher in Vienna Austria, home of the Sachertorte. Glasses fitted with corrective lenses are a common means of correcting focus problems such as myopia (nearsightedness, short-sightedness) and hyperopia (farsightedness, long-sightedness). Other establisments have given name to a particular meal or beverage, as is the case with the Waldorf Astoria in New York City, USA, known for its Waldorf Salad or the Raffles Hotel in Singapore, where the drink Singapore Sling was invented. Virtual reality glasses and helmets have separate video screens for each eye and a method for determining the direction the head is turned. Most world famous hotels have gained their renown through tradition, by hosting significant events or persons, such as Schloss Cecilienhof in Potsdam, Germany, which derives its fame from the so-called Potsdam Conference of the World War II allies Winston Churchill, Harry Truman and Joseph Stalin in 1945.

One kind of electronic 3D spectacles uses electronic shutters.
. Another kind of 3D glasses uses polarized filters. As this market is typically corporate travelers, the market segment is referral-rich, non-seasonal, high-yielding and repeat, and therefore one which boutique hotel operators target as their primary source of income. 3D glasses made of cardboard and plastic are distributed at 3D movies. Of the total travel market a small percentage are discerning travelers, who place a high importance on privacy, luxury and service delivery. The classic 3D glasses have one red lens and one blue lens. Many boutique hotels have on site dining facilities, and the majority offer bars and lounges which may also be open to the general public.

Classic 3D glasses create the illusion of three dimensions when viewing specially prepared images. Guest services are attended to by 24 hour hotel staff. The illusion of three dimensions on a two dimensional surface can be created by providing each eye with different visual information. Although usually considerably smaller than a mainstream hotel (ranging from 3 to 100 guest rooms) boutique hotels are generally fitted with telephony and wi-fi Internet connections, honesty bars and often cable/pay TV. Polarized sunglasses may present some difficulties for pilots in that reflections from water and other structures often used to gauge altitude may be removed, or instrument readings on liquid crystal displays may be blocked. Typically boutique hotels are furnished in a themed, stylish and/or aspirational manner. Popular among fishermen and hunters, polarized sunglasses allow wearers to see into water when normally glare or reflected light would be seen. Boutique hotels differentiate themselves from larger chain or branded hotels by providing an exceptional and personalized level accommodation, services and facilities.

Polarization filters remove horizontal rays of light, which can cause glare. "Boutique Hotel" is a term originating in North America to describe intimate, usually luxurious or quirky hotel environments. Light polarization is an added feature that can be applied to sunglass lenses. For the sake of greater comparability, rating systems have been introduced, with the one to five stars classification being most common. 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. Due to the enormous increase in tourism worldwide during the last decades of the 20th century, standards, especially those of smaller establishments, have improved considerably. Unfortunately, many car windshields protect the passengers from UV light, while not shielding from bright visible light, making photochromic lenses ineffective where they are most needed. The cost and quality of hotels are usually indicative of the range and type of services available.

Glasses with photosensitive lenses, called photochromic lenses, become darker in the presence of UV light. However, in Japan the capsule hotel supplies minimal facilities and room space. Sunglasses vary greatly and many offer more style than protection. In the United Kingdom a hotel is required by law to serve food and drinks to all-comers within certain stated hours; to avoid this requirement it is not uncommon to come across "private hotels" which are not subject to this requirement. It is possible to have lenses that look very dark and yet offer little ultraviolet protection. Food and drink may be supplied by a mini-bar (which often includes a small refrigerator) containing snacks and drinks (to be paid for on departure), and tea and coffee making facilities (cups, spoons, an electric kettle and sachets containing instant coffee, tea bags, sugar, and creamer or milk). Due to changes in the atmosphere, ultraviolet levels are much higher than in the past and ultraviolet protection for eyes and skin is even more important. Other features found may be a telephone, an alarm clock, a TV, and broadband Internet connectivity.

Good sunglasses should also protect against ultraviolet light. Basic accommodation of a room with a bed, a cupboard, a small table and a washstand only has largely been replaced by rooms with en-suite bathrooms and climate control. plano) lenses that are darkened to provide protection against bright visible light. The circumflex replaces the 's' once preceding the 't' in the earlier hostel spelling, which over time received a new, but closely related meaning. Sunglasses may be made with either prescription or non-prescription (i.e. The French spelling (with the circumflex) was once also used in English, but is now rare. Main article: Sunglasses. The word hotel derives from the French hôtel, which originally referred to a French version of a townhouse, not a place offering accommodation (in contemporary usage, hôtel has the meaning of "hotel", and hôtel particulier is used for the old meaning).

Corrective glasses with plastic lenses can often be used in the place of safety glasses in many environments; this is one advantage that they have over contact lenses. . The pictured wraparound safety glasses are evidence of this style change with the close fitting nature of the wraparound dispensing with the need for side shields. Hotels differ from motels in that most motels have drive-up, exterior entrances to the rooms, while hotels tend to have interior entrances to the rooms, making them safer and more relaxing to people. Recent safety glasses have tended to be given a more stylish design, in order to encourage their use. Some hotels have conference services and encourage groups to hold conventions and meetings at their location. They may provide less eye protection than goggles, face shields or other forms of eye protection, but their light weight increases the likelihood that they will actually be used. Hotels often provide a number of additional guest services such as a restaurant, a swimming pool or childcare.

Some safety glasses are designed to fit over corrective glasses or sunglasses. A hotel is an establishment that provides paid lodging, usually on a short-term basis and especially for tourists. The lenses of safety glasses can also be shaped for correction. Hotel. 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 Overlook Hotel from The Shining. Safety glasses can vary in the level of protection they provide. "Hollywood Tower Hotel" (ride at Disney-MGM Studios, Orlando, Florida).

Although safety lenses may be constructed from a variety of materials that vary in impact resistance, certain standards suggest that they maintain a minimum 1mm thickness at the thinest point regardless of material. Hotel Rwanda. Safety glasses are usually made with shatter-resistant plastic lenses to protect the eye from flying debris. Cyril Hare's Suicide Excepted. Lenses made to conform to the prescription of an ophthalmologist or optometrist are called prescription lenses and are used to make prescription glasses. At Bertram's Hotel. Glasses correcting for myopia will have negative diopter strengths. A Caribbean Mystery.

Over-the-counter reading glasses are typically rated at +1.00 to +3.00 diopters. Agatha Christie's Evil Under the Sun. The power of a lens is generally measured in diopters. "Hotel California". Corrective lenses modify the focal length of the eye to alleviate the effects of shortsightedness (myopia), longsightedness (hyperopia) or astigmatism. Hotelier. Either of these designs offers dramatically better ability to withstand the stresses of daily wear and the occasional accident. White Horse Inn.

Other frames have spring-loaded hinges. Fawlty Towers. For instance, it is now possible to purchase frames made of special memory metal alloys that return to their correct shape after being bent. The Hotel New Hampshire. Despite the increasing popularity of contact lenses and laser corrective eye surgery, glasses remain very common and their technology has not stood still. Tipton Hotel on Disney Channel's "The Suite Life of Zack and Cody". These designs were not immediately successful, however, and various styles with attached handles such as scissors glasses and lorgnettes remained fashionable throughout the 18th and into the early 19th century. Plaza Suite.

The modern style of glasses, held by temples passing over the ears, was developed in 1727 by the British optician Edward Scarlett. Room Service. Girolamo Savonarola 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 hat. Grand Hotel. Early eyepieces were designed to be either held in place by hand or by exerting pressure on the nose (pince-nez). Over time, the construction of spectacle frames also evolved.

The first lenses for correcting astigmatism were constructed by the British astronomer George Airy in 1827. The American scientist Benjamin Franklin, who suffered from both myopia and presbyopia, invented bifocals in 1784 to avoid having to regularly switch between two pairs of glasses. However, it was not until 1604 that Johannes Kepler published in his treatise on optics and astronomy, the first correct explanation as to why convex and concave lenses could correct presbyopia and myopia. Nicholas of Cusa is believed to have discovered the benefits of concave lens in the treatment of myopia (nearsightedness).

These early spectacles had convex lenses that could correct the farsightedness (presbyopia) that commonly develops as a symptom of aging. Bacon's published writings describe the magnifying glass (which he did not invent), but make no mention of glasses. Other stories, possibly legendary, credit Roger Bacon with the invention. In 1738, a Florentine historian named Domenico Manni reported that a tombstone in Florence credited one Salvino d'Armato (died 1317) with the invention of glasses.

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. In 1676, Franciscus Redi, a professor of medicine at the University of Pisa, 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, and a record of a sermon given in 1305, in which the speaker, a Dominican monk named Fra Giordano da Rivalto, remarked that glasses had been invented less than twenty years previously, and that he had met the inventor. The identity of the original inventor is unknown, although a possible source is the Arabs, who may have had magnifying lenses in the 10th century. Glasses were possibly invented in northern Italy, most likely in the late 1280s.

. Sunglasses protect against high levels of visible and ultraviolet light. Safety glasses are a kind of eye protection against flying debris or visible and near visible light or radiation. Corrective spectacles have lenses shaped to correct vision abnormalities, such as myopia.

Hydrophobic coatings designed to ease cleaning are also available, as are anti-reflective coatings intended to improve night vision and make the wearer's eyes more visible. Scratch-resistant coatings can be applied to most plastic lenses giving them similar scratch resistance to glass. Some plastics have a greater index of refraction than most types of glass, allowing thinner lenses for a given prescription. Some plastics also have more advantageous optical properties than glass, such as better transmission of visible light and greater absorption of ultraviolet light.

Glasses were originally made from glass, but many are now made from plastic (often polycarbonate or CR-39) due to the danger of breakage and the greater weight of glass lenses. In hipster slang they are cheaters. Spectacles is often shortened to specs. Glasses are more often called eyeglasses in North American English, occasionally spectacles in British English, and (rarely) frames or lenses.

Historical types include the pince nez, monocle, and lorgnette. Modern glasses are typically supported by pads on the bridge of the nose and by temples placed over the ears. Special glasses are used for viewing three-dimensional images or experiencing virtual reality. Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the human eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection.

Eyeglasses were a common part of the hipster persona, for example Dizzy Gillespie. Cheaters is used in the hipster argot. Lenses is also sometimes used to refer to framed eyepieces, although it is not common. Frames is sometimes used to refer to framed eyepieces, although it is not common.

In contrast, glass eye refers to a cosmetic prosthetic artificial eye that replaces a missing eye. Eye glasses or eyeglasses is a word used in North American English. Also in frequent use is the shortened form, specs. Spectacles is widely used in Britain and occasionally in the US, in addition to use by professional opticians.

Compare with other meanings of the word glass. Pair of glasses (or just glasses) is commonly used in Britain and in North America.

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