Eyeglasses

Eyeglasses, also called spectacles or glasses, are lenses set into a frame with a bridge over the nose and hinged temple arms that rest on the ears, worn chiefly to correct vision and also for eye protection or fashion. The earliest vision aids were 13th century Italian reading stones, magnifying spheres of glass or crystal that had to be held directly over a page, and the first true glasses appeared in central Italy around 1290; a Dominican friar named Giordano da Pisa said in a 1306 sermon that it was not yet twenty years since the art of making glasses had been found. Venice became a center of their manufacture soon after, with guild regulations in place by 1301 and a dedicated spectacle makers guild formed in 1320, though the now familiar temple arms that hook over the ears were not invented until the 1700s. A corrective lens works by bending light entering the eye so that the image falls back into focus on the retina, correcting refractive errors such as nearsightedness, farsightedness, and astigmatism according to a prescription from an eye care professional.