Glasses

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 glasses
• 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
• 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 plastic using super-fine polyamide powder and Selective laser sintering processes—see Mykita Mylon (The frames can be 3D-printed by Fused Filament Fabrication for pennies of ABS, PLA or nylon)
• Nylon

Metal

Various metals and alloys may be used to make glasses, such as gold, silver, aluminum, beryllium, stainless steel, titanium, Monel, and nickel titanium.

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 glasses as a fashion item, when frames were constructed with only functionality in mind, virtually all glasses were either round, oval, panto, rectangular, octagonal, or square. 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 the Greek and Roman era, most prominently the use of an emerald by Emperor Nero as mentioned by Pliny the Elder.

The use of a convex lens to form an enlarged/magnified image was most likely described in Ptolemy's Optics (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, c. 1021). 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 is also known to have written on the magnifying properties of lenses. The development of the first glasses took place in northern Italy 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, and the Inuit have used snow goggles for eye protection.

Invention

The earliest recorded comment on the use of lenses for optical purposes was made in 1268 by Roger Bacon.

The first glasses were estimated to have been made in central Italy, most likely in Pisa or Florence, by about 1290: In a sermon delivered on 23 February 1306, the Dominican friar Giordano da Pisa (c. 1255–1311) wrote "It is not yet twenty years since there was found the art of making glasses, 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 glasses. 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 [Spina] made them and shared them with everyone with a cheerful and willing heart." Venice quickly became an important center of manufacture, especially due to using the high-quality glass made at Murano. By 1301, there were guild regulations in Venice governing the sale of glasses 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 glasses 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 glasses found north of the Alps in an altarpiece of the church of Bad Wildungen (now in Germany) in 1403. These early glasses had convex lenses that could correct both hyperopia (farsightedness), and the presbyopia 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 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 near Celle in Germany; they have been dated to circa 1400.

The world's first specialist shop for spectacles—what might be regarded today as an optician—opened in Strasbourg (then Holy Roman Empire, now France) in 1466.

Other claims

The 17th-century claim by Francesco Redi that Salvino degli Armati of Florence invented glasses in the 13th century has been exposed as erroneous.

Marco Polo is mistakenly claimed to have encountered glasses during his travels in China in the 13th century. However, no such evidence appears in his accounts. The earliest mentions of glasses in China occur in the 15th century and those Chinese sources state that glasses 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.

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 glasses in Italy was established, including significant shipments of glasses 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, who had both myopia and presbyopia, 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 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 solution into a flexible lens.

Despite the popularity of contact lenses and laser 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.

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.

Widespread availability

The availability of glasses to ordinary people is still an ongoing problem, with between 1 and 2.5 billion people worldwide lacking access to vision correction.

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 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 glasses as a style accessory. In Japan, some companies ban women from wearing glasses.

Personal image

For most of their history, glasses 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 was regularly photographed wearing glasses, 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 glasses 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, glasses have become an acceptable fashion item and often act as a key component in individuals' personal image. Musicians Buddy Holly and John Lennon 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 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 by allowing him to "hear" vibrations. Some celebrities have become so associated with their glasses that they continued to wear them even after taking other measures against vision problems: U.S. Senator Barry Goldwater 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; 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 fiction, glasses 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 is well known for wearing 1950s-style horn-rimmed glasses as Clark Kent, while Wonder Woman wears either round, Harold Lloyd-style glasses or 1970s-style bug-eye glasses as Diana Prince. Sailor Mercury is also known for her glasses and her visor. An example of the halo effect is seen in the stereotype 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, glasses 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
• Wayfarer sunglasses
• Windsor glasses

General and cited bibliography

• Ilardi, Vincent (2007), Renaissance Vision from Spectacles to Telescopes, Philadelphia: American Philosophical Society, ISBN 9780871692597.
• Needham, Joseph (1962), "Part 1", Science & Civilisation in China, vol. IV, Cambridge, England: Cambridge University Press. Reprint: ISBN 9780521058025.