Gold Spectacles With Curved Ear Pieces, Bifocal Lenses
ca. Early 20th cen.
Bifocal lenses, initially developed by Benjamin Franklin, solve the problem of assisting people to see up close and at a distance. Because bifocals are often considered unfashionable, many current versions do not have a line that would indicate their purpose to others.
From the Abraham Pollen Archives, Massachusetts Eye and Ear Infirmary.