People with conditions that have photophobia as a primary symptom (like certain migraine disorders) often wear sunglasses or precision tinted glasses, even indoors and at night.

Even with glasses used for vision correction, a wide range of fashions are available, using plastic, metal, wire, and other materials for frames.

For people with presbyopia and hyperopia, bifocal and trifocal glasses provide two or three different refractive indices, respectively, and progressive lenses have a continuous gradient.

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.

[5] 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.

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.

[13][15][contradictory] The problem of computer vision syndrome (CVS) can result from focusing the eyes on a screen for long, continuous periods.

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.

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.

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).

[28][29] 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".

[36] The first eyeglasses 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 eyeglasses, which make for good vision ... And it is so short a time that this new art, never before extant, was discovered. ...

[39] 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,[41][42] 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 in an altarpiece of the church of Bad Wildungen, Germany, in 1403.

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.

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

[53] 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",[54] 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,[55] as well as a spectacles dispensary in Strasbourg in 1466.

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.

[59] 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.

[60] Graham Pullin describes how devices for disability, like glasses, have traditionally been designed to camouflage against the skin and restore ability without being visible.

[60] 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.

Advertising restrictions in the United States, for example, have correlated with higher prices, suggesting that adverts make the spectacles market more price-competitive.

[74][75] 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.

Senator Barry Goldwater and comedian Drew Carey continued to wear non-prescription glasses after being fitted for contacts and getting laser eye surgery, respectively.

I am interested in the remarks of Prof. J. HIRSCHBERG on the "History of the Invention of Glasses" published in the last issue of this journal (Volume VI, pp.

I, therefore, limit my criticism of it as far as possible and prefer to prove, by means of new material from Chinese literature, that the view of the original invention of spectacles in India is the greatest probability.

HIRSCHBERG theory is highly unlikely, as all previous experience has shown and contradicts analogies in cultural history and in the history of inventions in particular; Crystal spectacles appear in the European Middle Ages, in India, and in China, and from the historical point of view one can suppose from the outset that these inventions did not occur independently in each of these three cultural groups, but that a historical connection is here present.