The Difference Between Bifocals and Regular Glasses

The first spectacles were made between 1268 and 1289, according to Teagle Optometry. Since that time, eyeglasses have gone through many changes. One of the biggest changes to eyeglasses was the creation of bifocals. Benjamin Franklin was the creator of this type around 1760.

Eyeglass Invention

• In 1268 Roger Bacon wrote that using a medium of glass or crystal with the convex side facing the eye, a person could see the letter better and that the letters seem larger. In 1289 di Popozo wrote that without the glasses known as spectacles he would no longer be able to read or write, and that spectacles were invented for poor old people whose sight had weakened. In 1306 a monk of Pisa said in a sermon that it had been 20 years since spectacles had been created. This evidence shows that spectacles, or eyeglasses, were first used sometime between 1268 and 1289.

Eyeglass Frames

• From the moment spectacles were created, wearers had the problem of figuring out how to keep them on. It wasn't until 1730 that a London optician, Edward Scarlett, created a rigid sidepiece that rested on top of the ears. In 1752, James Ayscough, created the double-hinged side piece.

The Bifocal

• Benjamin Franklin became frustrated with having to change eye glasses every time he was working on something different. He had a pair of glasses for reading or close up work and another pair for distance. Between 1760 and 1780 he invented and developed the bifocal lens, allowing him to see both far and near with the same pair of glasses. By simply looking through the upper section he could see far away, looking down he could clearly read.

Bifocal Changes

• When the bifocal lens was first introduced, the convex lenses for far-sightedness and concave lenses for near-sightedness were apparent. You could visually see the upper part of the lens protruding out and the lower section pushing in. Technology has progressed to the point that only a thin line is visible between the two lens types. As a matter of fact, you can get lenses that do not show a line at all; these are called progressive lenses and only the eyeglass wearer can tell that they are wearing two different prescription lens types at once.