Reading Glasses

Plus lenses that aid near vision in presbyopia

Overview

Reading glasses are convex, plus powered spectacle lenses that magnify and bring near objects into focus, compensating for the loss of accommodation in presbyopia. Ready made reading glasses, sold without a prescription in many countries, have equal power in both lenses and no correction for astigmatism, and are produced in a range of standard powers. Prescription reading glasses can incorporate different powers for each eye, cylindrical correction, and prism. Half eye frames allow the wearer to look over the lenses at distant objects, while full frame readers blur distance vision. Alternatives for people who need both distance and near correction include bifocals, invented in the eighteenth century and popularly associated with Benjamin Franklin, trifocals, and progressive addition lenses, as well as occupational lenses designed for intermediate computer distances. Spectacles to aid reading are documented in Italy from the late thirteenth century, and convex reading stones, polished lenses laid on text, were used even earlier in medieval Europe.