In simple words, eyeglasses are a combination of frames and lenses that can be worn in front of people’s eyes for the purpose of correcting vision and protecting eyes from harms of UV rays or some other special threats in different environments.
A pair of typical contemporary eyeglasses consists of two temples, two hinges, two noses, a bridge and two pieces of lenses. Early lenses are made of quartz which was very expensive. It took hundreds of years for scientists to develop the eyeglasses lenses out of glass which made the eyeglasses lenses a lot less costly and affordable to general people. Modern eyeglasses lenses are mainly made of plastic making the lenses of the eyeglasses more breakage-resistant. The two mostly-used plastic materials are CR-39 and polycarbonate. Frames of eyeglasses are basically made of metals and/or plastic. Most of the efforts made in present days are to reduce the weight of eyeglasses and made the eyeglasses-wearing more comfortable and be a piece of art and fashion.
As for the history of eyeglasses, the concrete inventor of eyeglasses was unknown. It was around 1000AD, the first corrective vision aid called reading stone was invented, it was a quartz sphere that was put on top of the target(book) to be read and was used as a magnifier. The first wearable eyeglasses was believed to be invented by an Italian Salvino D’Armate around 1284.
Some historians believe that Chinese invented the eyeglasses 2000 years ago. But it was not for the purpose of magnifying and corrective function, it was for the protection of eyes from some evil forces.
In United States about 60-70% of the adult people are wearing all types of eyeglasses, including sunglasses.
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