Eyeglasses, 1284 – Once so expensive they were included in wills

Historian Lois N. Magner writes: "The use of eyeglasses must have had a profound effect on attitudes toward human limitations and responsibilities. Glasses not only enabled scholars and translators to continue their work, but also accustomed people to the idea that certain physical limitations could be overcome through human inventions."

Today, the terms glasses and optics generally refer to lenses fitted in a frame to correct vision problems. Various forms have existed throughout history, including pince-nez (supported by pinching the bridge of the nose, without earpieces), monocles (a circular lens over one eye) and lorgnettes (glasses with long handles).

By AD 1000, "reading stones," crystals or pieces of a glass sphere placed over reading material to magnify the text, were common. Glasses were used in China around 1270, during Marco Polo’s travels, and may have been used earlier in Arabia.

In 1284, the Italian Salvino D’Armate became perhaps the best-known inventor of eyeglasses in Europe. Early glasses used convex lenses to correct hyperopia (difficulty seeing nearby objects) and presbyopia (age-related difficulty with near vision). An early reference to concave lenses for nearsightedness, also called myopia, in which distant objects appear blurred and nearby objects clear, appeared in Natural Magick (scientific work-1558) by Italian scientist Giambattista della Porta. Convex lenses were used to see text close to the eye.

Glasses were once so expensive that they were listed as valuable possessions in wills. Around 1727, English optician Edward Scarlett developed the modern style of spectacles held in place by rigid arms resting on the ears. American scientist Benjamin Franklin invented bifocals (glasses with two focal lengths) in 1784 to address a combination of myopia and presbyopia.

Today, many eyeglasses are made from CR-39 plastic because of its favorable optical properties and durability. Lenses are generally used to change the focal position of light rays so that they properly intersect the retina, the light-sensitive tissue at the back of the eye.

Description of the article image: A lorgnette is a pair of glasses with a handle. It was invented in the 1700s by English optical designer George Adams. Some owners did not need glasses to see better, but carried ornate lorgnettes for style.

Historical figures mentioned in the article: Salvino D’Armate of Florence (1258–1312), Giambattista della Porta (1535–1615), Edward Scarlett (1677–1743)

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