types of bifocal reading glasses
The glasses originally were created to assist people who had trouble seeing both far away and up close. Rather than switch between two pairs of glasses, Franklin devised a way to have both lenses fit into one frame. Today, there are many different types of bifocal glasses available. Equal division lenses, segmented bifocals and blended lenses â also called seamless or invisible bifocals â are three main types of bifocals. Equal division bifocal glasses feature lenses cut in two distinct halves, with the magnification part on the lower half and the long-distance lens on the upper half.