Most people know Benjamin Franklin as "The First American," a noted diplomat and scientist, as well as for his important work with electricity. But did you know that this Founding Father, known for his signature glasses, is credited with the invention of bifocals?

Necessity Breeds Invention

Ben Franklin invented bifocal eyeglasses in 1784 for his own use, as he was having trouble seeing both up-close and at greater distances. Thus, rather than constantly changing glasses throughout the day, he created a method for placing differently-calibrated lenses into the same frame. His new "double spectacles" had pairs of half-lenses arranged in a top-bottom configuration. More convex lenses for nearby viewing were at the bottom and flatter lenses for distance sight were on top. Franklin commented in correspondence that now resides in the Library of Congress, that all he had to do was but move his eyes up or down, and the proper glass was always ready!

Bifocals Over Time

The technology for eyewear has come a long way in the past two-hundred years. The initial design - with the line across the width of the glass - was first called the Franklin bifocal and later the Executive bifocal. In later years, smaller rounded lens segments called "segs" were created for nearby vision, and scientists developed techniques to fuse the segs into the larger distance lens. More recently, D-shaped near segments - also known as "flat-top" or "straight-top" bifocals - became a popular alternative. There are new techniques that reduce eye strain when moving back and forth between distances throughout the day, and research is ongoing for lenses that use liquid crystal layers between glass substrates to selectively adjust the optical power as needed!

Right for You

Both bi- and trifocals exist to suit your exact vision condition. Presbyopia, or the loss of ability to focus especially on close up objects, can cause eyestrain and headache. This can often occur after age 50, when one's depth of focus can be decreased. These types of eyewear are often given to people with that diagnosis in order to restore reading vision. Trifocals can assist people who have difficulty seeing at arm's length in addition to reading and farther distances. Furthermore, progressive lenses provide multifocal correction with no apparent line to reveal any difference from single-lens glasses. There is plenty of variety in styles and frames to fit your budget and fashion concerns. With hundreds of styles and many types of transitions, you can find a pair to match your needs perfectly!

Your local eye doctor can make a proper diagnosis and prescription with a quick and painless visit. If you are having difficulty seeing at various distances, or even if it's just been a while since your last exam, call up your local eye doctor and set up an exam. Adults should have their eyes examined a minimum of once every two years, and senior citizens should be sure to have their eyes checked annually.


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