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Glasses, also known as eyeglasses (
American English American English, sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. English is the Languages of the United States, most widely spoken lang ...
), spectacles ( Commonwealth English), or colloquially as specs, are
vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...
eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears for support. Glasses are typically used for vision correction, such as with reading glasses and glasses used for nearsightedness; however, without the specialized lenses, they are sometimes used for cosmetic purposes. Safety glasses are eye protection, a form of personal protective equipment ( PPE) that are worn by workers around their eyes for protection. Safety glasses act as a shield to protect the eyes from any type of foreign debris that may cause irritation or injury; these glasses may have protection on the sides of the eyes as well as in the lenses. Some types of safety glasses are used to protect against visible and near-visible light or
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...
. Glasses are worn for eye protection in some sports, such as squash. Glasses wearers may use a strap to prevent the glasses from falling off. Wearers of glasses that are used only part of the time may have the glasses attached to a cord that goes around their neck to prevent the loss and breaking of the glasses. Sunglasses allow for better vision in bright daylight and are used to protect one's eyes against damage from excessive levels of ultraviolet light. Typical sunglasses lenses are tinted for protection against bright light or polarized to remove glare; photochromic glasses are clear or lightly tinted in dark or indoor conditions, but turn into sunglasses when they come into contact with ultraviolet light. Most over-the-counter sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be made. People with conditions that have
photophobia Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence o ...
as a primary symptom (like certain migraine disorders) often wear sunglasses or precision tinted glasses, even indoors and at night. Specialized glasses may be used for viewing specific visual information, for example, 3D glasses for 3D films (
stereoscopy Stereoscopy, also called stereoscopics or stereo imaging, is a technique for creating or enhancing the depth perception, illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives . Any ster ...
). Sometimes glasses are worn purely for fashion or aesthetic purposes. Even with glasses used for vision correction, a wide range of fashions are available, using plastic, metal, wire, and other materials for frames. Most glasses lenses are made of plastic, polyethylene, and glass.


Types

Glasses can be marked or found by their primary function, but also appear in combinations such as prescription sunglasses or safety glasses with enhanced magnification.


Corrective

Corrective lenses are used to correct
refractive error Refractive error is a problem with focus (optics), focusing light accurately on the retina due to the shape of the eye and/or cornea. The most common types of refractive error are myopia, near-sightedness, hyperopia, far-sightedness, astigmatis ...
s by bending the light entering the eye in order to alleviate the effects of conditions such as nearsightedness (myopia), farsightedness (hypermetropia) or astigmatism. The ability of one's eyes to accommodate their focus to near and distant focus alters over time. A common condition in people over forty years old is
presbyopia Presbyopia is a physiological insufficiency of optical Accommodation (vertebrate eye), accommodation associated with the aging of the human eye, eye; it results in progressively worsening ability to focus clearly on close objects. Also known as ...
, which is caused by the eye's crystalline lens losing elasticity, progressively reducing the ability of the lens to accommodate (i.e. to focus on objects close to the eye). Few people have a pair of eyes that show exactly equal refractive characteristics; one eye may need a "stronger" (i.e. more refracting) lens than the other. Corrective lenses bring the image back into focus on the retina. They are made to conform to the prescription of an
ophthalmologist Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...
or optometrist. A lensmeter can be used to verify the specifications of an existing pair of glasses. Corrective eyeglasses can significantly improve the life quality of the wearer. Not only do they enhance the wearer's visual experience, but can also reduce problems that result from eye strain, such as headaches or squinting. The most common type of corrective lens is "single vision", which has a uniform
refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...
. For people with
presbyopia Presbyopia is a physiological insufficiency of optical Accommodation (vertebrate eye), accommodation associated with the aging of the human eye, eye; it results in progressively worsening ability to focus clearly on close objects. Also known as ...
and hyperopia, bifocal and trifocal glasses provide two or three different refractive indices, respectively, and
progressive lenses Progressive may refer to: Politics * Progressivism, a political philosophy in support of social reform ** Progressivism in the United States, the political philosophy in the American context ** Progressivism in South Korea, the political phil ...
have a continuous gradient. Lenses can also be manufactured with high refractive indices, which allow them to be more lightweight and thinner than their counterparts with "low" refractive indices. Reading glasses provide a separate set of glasses for focusing on close by objects. Reading glasses are available without prescription from drugstores, and offer a cheap, practical solution, though these have a pair of simple lenses of equal power, and so will not correct refraction problems like astigmatism or refractive or prismatic variations between the left and right eye. For the total correction of the individual's sight, glasses complying to a recent ophthalmic prescription are required. People who need glasses to see often have corrective lens restrictions on their driver's licenses that require them to wear their glasses every time they drive or risk fines or jail time. Some militaries issue prescription glasses to servicemen and women. These are typically GI glasses. Many state prisons in the United States issue glasses to inmates, often in the form of clear plastic aviators. Adjustable-focus eyeglasses might be used to replace bifocals or trifocals, or might be used to produce cheaper single-vision glasses (since they do not have to be custom-manufactured for every person). Pinhole glasses are a type of corrective glasses that do not use a lens. Pinhole glasses do not actually refract the light or change focal length. Instead, they create a
diffraction Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation ...
limited system, which has an increased depth of field, similar to using a small aperture in photography. This form of correction has many limitations that prevent it from gaining popularity in everyday use. Pinhole glasses can be made in a DIY fashion by making small holes in a piece of card which is then held in front of the eyes with a strap or cardboard arms. Glasses may also house other corrective or assistive devices. After the development of the
transistor A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...
in the 1940s, combined eyeglass-hearing aids became popular. With thick-rimmed glasses the fashion at the time, a hearing aid could be concealed in the temple part of the frame. These fell out of fashion after the 1970s, but there are still occasions when combined eyeglass-hearing aids may be useful.


Safety

Safety glasses are worn to protect the eyes in various situations. They are made with break-proof plastic lenses to protect the eye from flying debris or other matter. Construction workers, factory workers, machinists and lab technicians are often required to wear safety glasses to shield the eyes from flying debris or hazardous splatters such as blood or chemicals. As of 2017, dentists and surgeons in Canada and other countries are required to wear safety glasses to protect against infection from patients' blood or other body fluids. There are also safety glasses for
welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...
, 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. Nylon frames are usually used for protective eyewear for sports because of their lightweight and flexible properties. Unlike most regular glasses, safety glasses often include protection beside the eyes as well as in front of the eyes.


Sunglasses

Sunglasses provide more comfort and protection against bright
light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...
and often against
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
(UV) light. To properly protect the eyes from the dangers of UV light, sunglasses should have UV-400 blocker to provide good coverage against the entire light spectrum that poses a danger. Light polarization is an added feature that can be applied to sunglass lenses. Polarization filters are positioned to remove horizontally polarized rays of light, which eliminates glare from horizontal surfaces (allowing wearers to see into water when reflected light would otherwise overwhelm the scene). Polarized sunglasses may present some difficulties for pilots since reflections from water and other structures often used to gauge altitude may be removed.
Liquid-crystal display A liquid-crystal display (LCD) is a flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liq ...
s emit polarized light, making them sometimes difficult to view with polarized sunglasses. Sunglasses may be worn for aesthetic purposes, or simply to hide the eyes. Examples of sunglasses that were popular for these reasons include tea shades and mirrorshades. Many blind people wear nearly opaque glasses to hide their eyes for cosmetic reasons. Many people with light sensitivity conditions wear sunglasses or other tinted glasses to make the light more tolerable. Sunglasses may also have corrective lenses, which requires a prescription. Clip-on sunglasses or sunglass clips can be attached to another pair of glasses. Some wrap-around sunglasses are large enough to be worn over another pair of glasses. Otherwise, many people opt to wear contact lenses to correct their vision so that standard sunglasses can be used.


Mixed double-frame (Flip glasses)

The double frame uplifting glasses have one moving frame with one pair of lenses and the basic fixed frame with another pair of lenses (optional), that are connected by four-bar linkage. For example, sun lenses could be easily lifted up and down while mixed with myopia lenses that always stay on.
Presbyopia Presbyopia is a physiological insufficiency of optical Accommodation (vertebrate eye), accommodation associated with the aging of the human eye, eye; it results in progressively worsening ability to focus clearly on close objects. Also known as ...
lenses could be also combined and easily removed from the field of view if needed without taking off glasses. These glasses are often used for drivers going through tunnels, with the upper frame serving as sunglasses and the second frame as transparent lenses.


3D glasses

The illusion of three dimensions on a two-dimensional surface can be created by providing each eye with different visual information. 3D glasses create the illusion of three dimensions by filtering a signal containing information for both eyes. The signal, often light reflected off a movie screen or emitted from an electronic display, is filtered so that each eye receives a slightly different image. The filters only work for the type of signal they were designed for. Anaglyph 3D glasses have a different colored filter for each eye, typically red and blue or red and green. A polarized 3D system on the other hand uses polarized filters. Polarized 3D glasses allow for color 3D, while the red-blue lenses produce an image with distorted coloration. An active shutter 3D system uses electronic shutters. Head-mounted displays can filter the signal electronically and then transmit light directly into the viewer's eyes. Anaglyph and polarized glasses are distributed to audiences at 3D movies. Polarized and active shutter glasses are used with many home theaters. Head-mounted displays are used by a single person, but the input signal can be shared between multiple units.


Magnification (bioptics)

Glasses can also provide magnification that is useful for people with vision impairments or specific occupational demands. An example would be '' bioptics'' or ''bioptic telescopes'' which have small
telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...
s mounted on, in, or behind their regular lenses. Newer designs use smaller lightweight telescopes, which can be embedded into the corrective glass and improve aesthetic appearance (mini telescopic spectacles). They may take the form of self-contained glasses that resemble goggles or binoculars, or may be attached to existing glasses.


Recumbent glasses

Recumbent or prism glasses are glasses that use a prism with a 90°
refraction In physics, refraction is the redirection of a wave as it passes from one transmission medium, medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commo ...
to allow the wearer to read or view a screen while lying on their back. Developed by Liverpudlian ophthalmologist Andrew McKie Reid in the 1930s to assist people bedbound by chronic illness or spinal injury, recumbent glasses have more recently been marketed not simply as an assistive device but also as 'lazy glasses'. They do not assist with vision, although they can be worn over regular corrective glasses.


Yellow-tinted computer/gaming glasses

Yellow-tinted glasses are a type of glasses with a minor yellow tint. They perform a slight color correction, on top of reducing eyestrain from lack of blinking. They may also be considered minor corrective non-prescription glasses. Depending on the company, these computer or gaming glasses can also filter out high energy blue and ultra-violet light from LCD screens, fluorescent lighting, and other sources of light. This allows for reduced eye-strain. These glasses can be ordered as standard or prescription lenses that fit into standard optical frames.


Blue-light blocking glasses

By the end of the 2010s, eyeglasses that filter out blue light from
computers A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...
, smartphones and tablets are becoming increasingly popular in response to concerns about problems caused by blue light overexposure. The problems claimed range from dry eyes to eye strain, sleep cycle disruption, up to macular degeneration which can cause partial blindness. They may also block out
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
(UV) radiation. However, there is no measurable UV light from computer monitors. The problem of computer vision syndrome (CVS) can result from focusing the eyes on a screen for long, continuous periods. Many times the glasses do not appear to have much of a tint, or, if any, a slight yellow tint, but they may be more heavily tinted. Long hours of computer use (not blue light) may cause eye strain. Many eye symptoms caused by computer use will lessen after the usage of the computer is stopped. Decreasing evening screen time and setting devices to night mode will improve sleep. Several studies have shown that blue light from computers does not lead to eye diseases, including macular degeneration. The total amount of light entering the eyes can be adjusted without glasses using the screen brightness settings. Similarly, the blue light can often specifically be adjusted using the "night mode" of different operating systems, which can usually be activated outside of nighttime hours. The American Academy of Ophthalmology (AAO) does not recommend special eyewear for computer use, although it recommends using prescription glasses measured specifically for computer screen distance (depending on individuals, but possibly 20–26 inches from the face), which are not the same as "blue-light blocking" glasses. The position of the College of Optometrists (UK) is that "the best scientific evidence currently available does not support the use of blue-blocking spectacle lenses in the general population to improve visual performance, alleviate the symptoms of eye fatigue or visual discomfort, improve sleep quality or conserve macula health."


Frames

The ophthalmic frame is the part of a pair of glasses that is designed to hold the lenses in the proper position. Ophthalmic frames come in a variety of styles, sizes, materials, shapes, and colors.


Parts

* pair of eye wires or rims surrounding and holding the lenses in place * bridge which connects the two eye wires * chassis, the combination of the eye wires and the bridge * top bar or brow bar, a bar just above the bridge providing structural support and/or style enhancement (country/Grandpa style). The addition of a top bar makes a pair of glasses aviator eyeglasses * pair of brows or caps, plastic or metal caps which fit over the top of the eye wires for style enhancement and to provide additional support for the lenses. The addition of brows makes a pair of glasses browline glasses * pair of nose pads that allows a comfortable resting of the eye wires on the nose * pair of pad arms connect the nose pads to the eye wires * pair of temples (earpieces) on either side of the skull * pair of temple tips at the ends of the temples * pair of end pieces connect the eye wires via the hinges to the temples * pair of frame-front end pieces * pair of hinges connect the end pieces to the temples, allowing a swivel movement. Spring-loaded flex hinges are a variant that is equipped with a small spring that affords the temples a greater range of movement and does not limit them to the traditional, 90-degree angle.


Temple types

* Skull temples: bend down behind the ears, follow the contour of the skull and rest evenly against the skull * Library temples: generally straight and do not bend down behind the ears. Hold the glasses primarily through light pressure against the side of the skull * Convertible temples: used either as library or skull temples depending on the bent * Riding bow temples: curve around the ear and extend down to the level of the ear lobe. Used mostly on athletic, children's, and industrial safety frames * Comfort cable temples: similar to the riding bow, but made from a springy cable of coiled metal, sometimes inside a plastic or silicone sleeve. The tightness of the curl can be adjusted along its whole length, allowing the back to fit the wearer's ear curve perfectly. Used for physically active wearers, children, and people with high prescriptions (heavy lenses). See the image of 1920s frames above.


Materials


Plastic and polymer

*
Cellulose acetate In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
* Optyl, a type of hypoallergenic material made especially for eyeglass frames. It features a type of elasticity that returns the material to its original shape. * Cellulose propionate, a molded, durable plastic *
3D-printed 3D printing, or additive manufacturing, is the Manufacturing, construction of a three-dimensional object from a computer-aided design, CAD model or a digital 3D modeling, 3D model. It can be done in a variety of processes in which material i ...
plastic using super-fine polyamide powder and Selective laser sintering processes – see Mykita Mylon (The frames can be 3-D printed by Fused Filament Fabrication for pennies of ABS, PLA or nylon) * Nylon


Metal

Various metals and
alloy An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...
s may be used to make glasses, such as gold, silver, aluminum,
beryllium Beryllium is a chemical element; it has Symbol (chemistry), symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with ...
,
stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...
, titanium, Monel, and
nickel titanium Nickel titanium, also known as nitinol, is a metal alloy of nickel and titanium, where the two elements are present in roughly equal atomic percentages. Different alloys are named according to the weight percentage of nickel; e.g., nitinol 55 and ...
.


Natural material

Natural materials such as wood, bone, ivory, leather and semi-precious or precious stones may also be used.


Corrective lens shape

Corrective lenses can be produced in many different shapes from a circular lens called a lens blank. Lens blanks are cut to fit the shape of the frame that will hold them. Frame styles vary and fashion trends change over time, resulting in a multitude of lens shapes. For lower power lenses, there are few restrictions, allowing for many trendy and fashionable shapes. Higher power lenses can distort peripheral vision and may become thick and heavy if a large lens shape is used. However, if the lens is too small, it can drastically reduce the field of view. Bifocal, trifocal, and progressive lenses generally require a taller lens shape to leave room for the different segments while preserving an adequate field of view through each segment. Frames with rounded edges are the most efficient for correcting myopic prescriptions, with perfectly round frames being the most efficient. Before the advent of eyeglasses as a fashion item, when frames were constructed with only functionality in mind, virtually all eyeglasses were either round, oval, panto, rectangular, octagonal, or
square In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...
. It was not until glasses began to be seen as an accessory that different shapes were introduced to be more aesthetically pleasing than functional.


History


Precursors

Scattered evidence exists for use of visual aid devices in Greek and Roman times, most prominently the use of an emerald by Emperor Nero as mentioned by
Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...
. The use of a convex lens to form an enlarged/magnified image was most likely described in
Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...
's ''
Optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...
'' (which survives only in a poor Arabic translation). Ptolemy's description of lenses was commented upon and improved by Ibn Sahl (10th century) and most notably by Alhazen ('' Book of Optics'', ). Latin translations of Ptolemy's ''Optics'' and of Alhazen became available in Europe in the 12th century, coinciding with the development of " reading stones". There are claims that single lens magnifying glasses were being used in China during the Northern Song dynasty (960–1127). Robert Grosseteste's treatise ''De iride'' (''On the Rainbow''), written between 1220 and 1235, mentions using optics to "read the smallest letters at incredible distances". A few years later in 1262,
Roger Bacon Roger Bacon (; or ', also '' Rogerus''; ), also known by the Scholastic accolades, scholastic accolade ''Doctor Mirabilis'', was a medieval English polymath, philosopher, scientist, theologian and Franciscans, Franciscan friar who placed co ...
is also known to have written on the magnifying properties of lenses. The development of the first eyeglasses took place in northern
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
in the second half of the 13th century. Independently of the development of optical lenses, some cultures developed " sunglasses" for eye protection, without any corrective properties. For example, flat panes of smoky quartz were used in 12th-century
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, and the
Inuit Inuit (singular: Inuk) are a group of culturally and historically similar Indigenous peoples traditionally inhabiting the Arctic and Subarctic regions of North America and Russia, including Greenland, Labrador, Quebec, Nunavut, the Northwe ...
have used snow goggles for eye protection. File:Tommaso da modena, ritratti di domenicani (Ugo di Provenza) 1352 150cm, treviso, ex convento di san niccolò, sala del capitolo.jpg, Detail of a portrait of the Dominican cardinal and renowned biblical scholar Hugh of Saint-Cher, painted by Tommaso da Modena in 1352 File:Portrait of a Cardinal by El Greco.jpg, Portrait of Cardinal Fernando Niño de Guevara by El Greco, c. 1600, showing glasses with temples passing over and around the ears File:Mu'in. Portrait of Riza-i-Abbasi. 1673. Princeton University..jpg, The Persian miniaturist
Reza Abbasi Reza Abbasi (), also known as Aqa Reza ( – 1635), was the leading Persian miniature, Persian miniaturist of the Isfahan School during the later Safavid period, spending most of his career working for Shah Abbas I. He is considered to be the l ...
wearing glasses, 1673.


Invention

The earliest recorded comment on the use of lenses for optical purposes was made in 1268 by
Roger Bacon Roger Bacon (; or ', also '' Rogerus''; ), also known by the Scholastic accolades, scholastic accolade ''Doctor Mirabilis'', was a medieval English polymath, philosopher, scientist, theologian and Franciscans, Franciscan friar who placed co ...
. The first eyeglasses were estimated to have been made in Central Italy, most likely in
Pisa Pisa ( ; ) is a city and ''comune'' (municipality) in Tuscany, Central Italy, straddling the Arno just before it empties into the Ligurian Sea. It is the capital city of the Province of Pisa. Although Pisa is known worldwide for the Leaning Tow ...
or
Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...
, by about 1290: In a sermon delivered on 23 February 1306, the Dominican friar Giordano da Pisa (–1311) wrote "It is not yet twenty years since there was found the art of making eyeglasses, which make for good vision ... And it is so short a time that this new art, never before extant, was discovered. ... I saw the one who first discovered and practiced it, and I talked to him." Giordano's colleague Friar Alessandro della Spina of Pisa (d. 1313) was soon making eyeglasses. The ''Ancient Chronicle of the Dominican Monastery of St. Catherine in Pisa'' records: "Eyeglasses, having first been made by someone else, who was unwilling to share them, he pinamade them and shared them with everyone with a cheerful and willing heart."
Venice Venice ( ; ; , formerly ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 islands that are separated by expanses of open water and by canals; portions of the city are li ...
quickly became an important center of manufacture, especially due to using the high-quality glass made at Murano. By 1301, there were
guild A guild ( ) is an association of artisans and merchants who oversee the practice of their craft/trade in a particular territory. The earliest types of guild formed as organizations of tradespeople belonging to a professional association. They so ...
regulations in Venice governing the sale of eyeglasses and a separate guild of Venetian spectacle makers was formed in 1320. In the fourteenth century, they were very common objects: Francesco Petrarca says in one of his letters that, until he was 60, he did not need glasses, and Franco Sacchetti mentions them often in his ''Trecentonovelle''. The earliest pictorial evidence for the use of eyeglasses is Tommaso da Modena's 1352 portrait of the cardinal Hugh de Saint-Cher reading in a scriptorium. Another early example would be a depiction of eyeglasses found north of the
Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...
in an altarpiece of the church of Bad Wildungen, Germany, in 1403. These early glasses had
convex lenses A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
that could correct both hyperopia (farsightedness), and the
presbyopia Presbyopia is a physiological insufficiency of optical Accommodation (vertebrate eye), accommodation associated with the aging of the human eye, eye; it results in progressively worsening ability to focus clearly on close objects. Also known as ...
that commonly develops as a symptom of aging. Although concave lenses for myopia (near-sightedness) had made their first appearance in the mid-15th century, it was not until 1604 that
Johannes Kepler Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best know ...
published the first correct explanation as to why convex and concave lenses could correct presbyopia and myopia. Early frames for glasses consisted of two magnifying glasses riveted together by the handles so that they could grip the nose. These are referred to as "rivet spectacles". The earliest surviving examples were found under the floorboards at Kloster Wienhausen, a
convent A convent is an enclosed community of monks, nuns, friars or religious sisters. Alternatively, ''convent'' means the building used by the community. The term is particularly used in the Catholic Church, Lutheran churches, and the Anglican ...
near Celle in Germany; they have been dated to ''circa'' 1400. The world's first specialist shop for spectacles—what we might regard today as an optician—opened in
Strasbourg Strasbourg ( , ; ; ) is the Prefectures in France, prefecture and largest city of the Grand Est Regions of France, region of Geography of France, eastern France, in the historic region of Alsace. It is the prefecture of the Bas-Rhin Departmen ...
(then
Holy Roman Empire The Holy Roman Empire, also known as the Holy Roman Empire of the German Nation after 1512, was a polity in Central and Western Europe, usually headed by the Holy Roman Emperor. It developed in the Early Middle Ages, and lasted for a millennium ...
, now France) in 1466.


Other claims

The 17th-century claim by
Francesco Redi Francesco Redi (18 February 1626 – 1 March 1697) was an Italians, Italian physician, naturalist, biologist, and poet. He is referred to as the "founder of experimental biology", and as the "father of modern parasitology". He was the first perso ...
that Salvino degli Armati of Florence invented eyeglasses in the 13th century has been exposed as erroneous.
Marco Polo Marco Polo (; ; ; 8 January 1324) was a Republic of Venice, Venetian merchant, explorer and writer who travelled through Asia along the Silk Road between 1271 and 1295. His travels are recorded in ''The Travels of Marco Polo'' (also known a ...
is mistakenly claimed to have encountered eyeglasses during his travels in China in the 13th century. However, no such evidence appears in his accounts. Section (History of Eyeglasses) From pp. 266–267 (translated): "3. Do the Europeans have the Chinese to thank for eyeglasses? ... Messrs. Scrini and Fortin in Paris have asserted this recently with the words: 'One knows, on the other hand, that when Marco Polo went to China, he learned that for a very long time already, the inhabitants had been using eyeglasses.' This assertion lacked any substantiation. So I have closely perused the German translation of 'the books of Marco Polo' (2nd ed., Leipzig 1855) once again as well as carefully compared hat bookto the original text (the book of Marco Polo by Pauthier, Paris 1865, 2 volumes): not a syllable about eyeglasses in China is found therein. Our highly esteemed Sinologist, Prof. Graube, had the kindness to peruse also the English edition (by Yule, London 1875), with the same negative result. Thus the sentence of Messrs. Scrini and Fortin is to be crossed out; this error may not be the only one to have infiltrated the literature." Indeed, the earliest mentions of eyeglasses in China occur in the 15th century and those Chinese sources state that eyeglasses were imported. In 1907, Professor Berthold Laufer speculated, in his history of glasses, that for glasses to be mentioned in the literature of China and Europe at approximately the same time it was probable that they were not invented independently, and after ruling out the Turks, proposed India as a location. However, Joseph Needham stated that the mention of glasses in the Chinese manuscript Laufer used "in part" to credit the prior invention of them in Asia did not exist in older versions of that manuscript, and the reference to them in later versions was added during the
Ming dynasty The Ming dynasty, officially the Great Ming, was an Dynasties of China, imperial dynasty of China that ruled from 1368 to 1644, following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming was the last imperial dynasty of ...
. In 1971, Rishi Agarwal, in an article in the '' British Journal of Ophthalmology'', states that Vyasatirtha was observed in possession of a pair of glasses in the 1520s, he argues that it "is, therefore, most likely that the use of lenses reached Europe via the Arabs, as did Hindu mathematics and the ophthalmological works of the ancient Hindu surgeon Sushruta", but all dates are given well after the existence of eyeglasses in Italy was established, including significant shipments of eyeglasses from Italy to the Middle East, with one shipment as large as 24,000 glasses, as well as a spectacles dispensary in Strasbourg in 1466.


Later developments

The American scientist
Benjamin Franklin Benjamin Franklin (April 17, 1790) was an American polymath: a writer, scientist, inventor, statesman, diplomat, printer, publisher and Political philosophy, political philosopher.#britannica, Encyclopædia Britannica, Wood, 2021 Among the m ...
, who had both myopia and
presbyopia Presbyopia is a physiological insufficiency of optical Accommodation (vertebrate eye), accommodation associated with the aging of the human eye, eye; it results in progressively worsening ability to focus clearly on close objects. Also known as ...
, invented bifocals. Historians have from time to time produced evidence to suggest that others may have preceded him in the invention; however, a correspondence between
George Whatley George Whatley (died 1791) was an English lawyer, a friend and correspondent of Benjamin Franklin. He was also Vice President (1772–1779) and Treasurer (1779–1791) of the Foundling Hospital in London. Whatley was the author of '' Principles ...
and John Fenno, editor of '' The Gazette of the United States'', suggested that Franklin had indeed invented bifocals, and perhaps 50 years earlier than had been originally thought. The first lenses for correcting astigmatism were designed by the British astronomer George Airy in 1825. Over time, the construction of frames for glasses 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 sometime before 1727, possibly 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 were also fashionable from the second half of the 18th century and into the early 19th century. In the early 20th century, Moritz von Rohr and Zeiss (with the assistance of H. Boegehold and A. Sonnefeld) developed the Zeiss Punktal spherical point-focus lenses that dominated the eyeglass lens field for many years. In 2008, Joshua Silver designed eyewear with adjustable corrective glasses. They work by using a built-in syringe to pump a
silicone In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...
solution into a flexible lens. Despite the popularity of contact lenses and
laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...
corrective eye surgery, glasses remain very common, as their technology has improved. 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 offer dramatically better ability to withstand the stresses of daily wear and the occasional accident. Modern frames are also often made from strong, lightweight materials such as titanium alloys, which were not available in earlier times. File:Don francisco de quevedo-villegas.jpg, A portrait of Francisco de Quevedo y Villegas, 1580–1645 File:Harry S. Truman.jpg, Harry S. Truman, 33rd President of the United States, had poor vision.


In fashion

In the 1930s, "spectacles" were described as "medical appliances". Wearing spectacles was sometimes considered socially humiliating. In the 1970s, fashionable glasses started to become available through manufacturers, and governments also recognized the demand for stylized eyewear. Graham Pullin describes how devices for disability, like glasses, have traditionally been designed to camouflage against the skin and restore ability without being visible. In the past, design for disability has "been less about projecting a positive image as about trying not to project an image at all". Pullin uses the example of spectacles, traditionally categorized as a medical device for "patients", and outlines how they are now described as eyewear: a fashionable accessory. Much like other fashion designs and accessories, eyewear is created by designers, has reputable labels, and comes in collections, by season and designer. In recent years, it has become more common for consumers to purchase eyewear with non-prescription lenses as a fashion accessory.


Society and culture


Market


United States

The market for spectacles has been characterized as having highly inelastic demand. Advertising restrictions in the United States, for example, have correlated with higher prices, suggesting that adverts make the spectacles market more price-competitive. It has also been claimed to be monopolistically competitive, as in the case of Luxottica. There are claims that insufficiently free
market competition In economics, competition is a scenario where different Economic agent, economic firmsThis article follows the general economic convention of referring to all actors as firms; examples in include individuals and brands or divisions within the s ...
inflates the prices of frames, which cost an average of $25–$50 U.S. to make, to an average retail price of $300 in the United States. This claim is disputed by some in the industry. The United States also prohibits the sale of glasses unless the user has a recent prescription from an optometrist or ophthalmologist, whereas in most of the world, glasses and contact lenses can be bought without needing to get a new eye exam first. This means that Americans who lose or break their glasses may be unable to see well until they can get, and pay for, an appointment with an optometrist. In most of the world, someone who has lost their glasses merely goes to the nearest store selling glasses and buys a replacement over the counter.


Redistribution

Some organizations like Lions Clubs International, Unite For Sight, ReSpectacle, and New Eyes for the Needy provide a way to donate glasses and sunglasses to people on low incomes or no income. Unite For Sight has redistributed more than 200,000 pairs.


Fashion

Many people require glasses for the reasons listed above. There are many shapes, colors, and materials that can be used when designing frames and lenses that can be utilized in various combinations. Oftentimes, the selection of a frame is made based on how it will affect the appearance of the wearer. Some people with good natural eyesight like to wear eyeglasses as a style accessory. In Japan, some companies ban women from wearing glasses.


Personal image

For most of their history, eyeglasses were seen as unfashionable, and carried several potentially negative connotations: wearing glasses caused individuals to be stigmatized and stereotyped as pious clergymen, as those in religious vocation were the most likely to be literate and therefore the most likely to need reading glasses, elderly, or physically weak and passive. The stigma began to fall away in the U.S. in the early 1900s when the popular
Theodore Roosevelt Theodore Roosevelt Jr. (October 27, 1858 – January 6, 1919), also known as Teddy or T.R., was the 26th president of the United States, serving from 1901 to 1909. Roosevelt previously was involved in New York (state), New York politics, incl ...
was regularly photographed wearing eyeglasses, and in the 1910s when popular comedian Harold Lloyd wore a pair of horn-rimmed glasses as the "Glasses" character in his films. In the United Kingdom, wearing glasses was characterized in the nineteenth century as "a sure sign of the weakling and the mollycoddle", according to Neville Cardus, writing in 1928. "Tim" Killick was the first professional cricketer to play while wearing glasses "continuously", after his vision deteriorated in 1897. "With their aid he placed himself in the forefront among English professionals of all-round abilities." The American tenor Jan Peerce, plagued with poor eyesight, credited comedian Steve Allen for normalizing and even popularizing the wearing of eyeglasses in front of live television and stage audiences; prior to this, performers who read on early television were expected to squint or use contact lenses. Since then, eyeglasses have become an acceptable fashion item and often act as a key component in individuals' personal image. Musicians Buddy Holly and
John Lennon John Winston Ono Lennon (born John Winston Lennon; 9 October 19408 December 1980) was an English singer-songwriter, musician and activist. He gained global fame as the founder, co-lead vocalist and rhythm guitarist of the Beatles. Lennon's ...
became synonymous with the styles of eye-glasses they wore to the point that thick, black horn-rimmed glasses are often called "Buddy Holly glasses" and perfectly round metal eyeglass frames called "John Lennon glasses" (or, more recently, "
Harry Potter ''Harry Potter'' is a series of seven Fantasy literature, fantasy novels written by British author J. K. Rowling. The novels chronicle the lives of a young Magician (fantasy), wizard, Harry Potter (character), Harry Potter, and his friends ...
glasses"). British comedic actor Eric Sykes was known in the United Kingdom for wearing thick, square, horn-rimmed glasses, which were in fact a sophisticated hearing aid that alleviated his
deafness Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is writte ...
by allowing him to "hear" vibrations. Some celebrities have become so associated with their eyeglasses that they continued to wear them even after taking other measures against vision problems: U.S. Senator
Barry Goldwater Barry Morris Goldwater (January 2, 1909 – May 29, 1998) was an American politician and major general in the United States Air Force, Air Force Reserve who served as a United States senator from 1953 to 1965 and 1969 to 1987, and was the Re ...
and comedian Drew Carey continued to wear non-prescription glasses after being fitted for contacts and getting laser eye surgery, respectively. Other celebrities have used glasses to differentiate themselves from the characters they play, such as Anne Kirkbride, who wore oversized 1980s-style round horn-rimmed glasses as Deirdre Barlow in the soap opera ''
Coronation Street ''Coronation Street'' (colloquially referred to as ''Corrie'') is a British television soap opera created by ITV Granada, Granada Television and shown on ITV (TV network), ITV since 9 December 1960. The programme centres on a cobbled, terraced ...
''; and Masaharu Morimoto, who wears glasses to separate his professional persona as a chef from his stage persona as Iron Chef Japanese. In 2012, some NBA players wore lensless glasses with thick plastic frames like horn-rimmed glasses during post-game interviews, geek chic that draws comparisons to actor Jaleel White's infamous styling as TV character Steve Urkel. In
superhero A superhero or superheroine is a fictional character who typically possesses ''superpowers'' or abilities beyond those of ordinary people, is frequently costumed concealing their identity, and fits the role of the hero, typically using their ...
fiction, eyeglasses have become a standard component of various heroes' disguises as masks, allowing them to adopt a nondescript demeanor when they are not in their superhero personae:
Superman Superman is a superhero created by writer Jerry Siegel and artist Joe Shuster, which first appeared in the comic book ''Action Comics'' Action Comics 1, #1, published in the United States on April 18, 1938.The copyright date of ''Action Comics ...
is well known for wearing 1950s-style horn-rimmed glasses as
Clark Kent Superman is a superhero created by writer Jerry Siegel and artist Joe Shuster, which first appeared in the comic book ''Action Comics'' Action Comics 1, #1, published in the United States on April 18, 1938.The copyright date of ''Action Comics ...
, while
Wonder Woman Wonder Woman is a superheroine who appears in American comic books published by DC Comics. The character first appeared in ''All Star Comics'' Introducing Wonder Woman, #8, published October 21, 1941, with her first feature in ''Sensation Comic ...
wears either round, Harold Lloyd-style glasses or 1970s-style bug-eye glasses as Diana Prince. An example of the halo effect is seen in the
stereotype In social psychology, a stereotype is a generalization, generalized belief about a particular category of people. It is an expectation that people might have about every person of a particular group. The type of expectation can vary; it can ...
that those who wear glasses are intelligent. This belief can have positive consequences for people who wear glasses, for example in elections. Studies show that wearing glasses increases politicians' electoral success, at least in Western cultures.


Styles

In the 20th century, eyeglasses came to be considered a component of fashion; as such, various different styles have come in and out of popularity. Most are still in regular use, albeit with varying degrees of frequency. * Aviator sunglasses * Browline glasses * Bug-eye glasses * Cat eye glasses * GI glasses * Goggles * Horn-rimmed glasses * Lensless glasses * Monocle * Pince-nez * Rimless glasses * Sunglasses * Ray-Ban Wayfarer, Wayfarer sunglasses * Windsor glasses


See also

* Adjustable-focus eyeglasses * Baden-Powell's unilens * Eye examination * Eyeglass prescription * History of optics * Plurale tantum * X-ray vision


Explanatory notes


References


General and cited bibliography

* . * .


External links


Spectacles Gallery
at the British Optical Association Museum * . * , on eyes and how eyeglasses correct vision (page 120).
"Common Spectacles Styles before, during and after the Civil War"
(2012 article) via the Internet Archive; Antique Eyeglasses in America. {{Authority control Glasses, Corrective lenses Italian inventions Protective gear Sports equipment