Glasses are devices made of two lenses that are held in front of a person’s eyes using a frame. They are often used to correct refractive errors, allowing people to see things clearly.
Also known as eyeglasses or spectacles, glasses are optical devices used to correct vision. They consist of lenses made of glass or plastic set into a frame that positions the lenses in front of a person’s eyes. A bridge is used to connect the two lenses across the nose. Glasses work by changing the direction of light rays to correct faulty lenses in the eye. They correct refractive errors when a person's lens doesn’t focus the light correctly on the retina. Corrective lenses bring the image back in focus at the back of the retina. They are used to reduce the effects of conditions such as nearsightedness, farsightedness, and astigmatism. Glasses have changed the world by helping people with eye conditions see things by corrective refractive errors. Glasses can also stop the wearer from headaches caused by blurry vision.
Lenses were first believed to be used as magnifying glasses, making it easier to see small things. Evidence shows that Emperor Nero used an emerald as a magnifying glass. The inventor and location of the first eyeglasses is not known with certainty. It is believed that they were invented in Italy some time in the 13th Century.
Early frames consisted of two lens held together with bars that could grip the nose. Bifocal glasses were invented by the American scientist Benjamin Franklin. Bifocal glasses have lenses with two different strengths, allowing them to correct multiple refractive errors. Glasses were essentially a medical device until the 20th century when the invention of new materials meant more fashionable glasses could be produced.
Sunglasses, which may or may not be corrective, allow users to see better by reducing the amount of light that enters the eye. Sunglasses also reduce the amount of ultraviolet light that enters the eye. Ultraviolet radiation can damage the eye permanently. Glasses can also protect eyes in some potentially dangerous situations. Safety glasses are used by people working in a range of industries, like construction and manufacturing, to protect their eyes from flying debris.