Also called spectacles, eyeglasses are the most common device for the correction of vision problems including hyperopia (farsightedness), myopia (nearsightedness), astigmatism (corneal distortion) and presbyopia (inability of eye to focus up close due to hardening of natural lens) The most common types of eyeglass lenses are single vision, bifocals, trifocals and multi-focals (progressive lenses) Eyeglass lens materials include glass and various types of plastic, including new materials that allow thinner, lighter-weight lenses Various treatments to the lenses include antireflection coating, photochromic (which darken when exposed to sunlight), polarized and toughened (for safety) See Prescription Eyeglasses in Eye Care Encyclopedia See Free Eye Tests
Eyeglasses are two lenses in a frame that some people wear in front of their eyes in order to help them see better. Lenses set in frames to wear in front of the eyes to aid vision or correct vision defects (see ophthalmology, optometry). Their use for farsightedness and nearsightedness has been known since the late Middle Ages. In 1784 Benjamin Franklin invented bifocals, with divided lenses for distant and near vision. Eyeglasses can also correct astigmatism. Most lenses are made of glass or plastic (lighter and more shatterproof than glass but easily scratched). Sunglass lenses are tinted to reduce glare and often treated to reduce ultraviolet light exposure. See also contact lens
spectacles; lenses ground to the specifications of a prescription which, when mounted into frames and worn on the face, aid in refocusing the light entering each eye onto the retina at the back of the eye, providing clear vision
[ 'I ] (noun.) before 12th century. Middle English, from Old English Eage; akin to Old High German ouga eye, Latin oculus, Greek Ops eye, face, Sanskrit aksi eye.