What Are Bifocals and How Do They Work?

OK...you'r over 40 years old and you can't read things up close. Maybe you have to take your glasses off and you can read. Maybe you need those $3.00 cheapo glasses from the pharmacy, even putting them on over your contact lenses. But you're starting to get cranky because of all the on-and-off with the glasses stuff. What to do? It's time to talk about bifocals.

Bifocals are glasses that have both a correction for your distance vision on the top of the lens, and a correction to help you read on the bottom. The first bifocal was actually invented by Benjamin Franklin. Yup...the same guy who did the whole kite and key thing to discover electricity! Ol' Ben just glued the top half of one lens to the bottom half of another and created what we now call an "Executive" bifocal.





This very simple type of lens has evolved into into more modern bifocal lenses. The most direct descendant of the Franklin lens is the Flat-top bifocal. These lenses have a very large area devoted to your distance vision, with a smallish insert or segment that allows you to focus on objects up close. The working distance, how far away you can hold something and still be in focus, is fixed with this type of bifocal.

What about seeing things a little further away, say a computer screen? And by the way, I think those bifocals where I can see the lines make me look older. Isn't there some kind of newer lens?




Absolutely! The most modern bifocal lenses are called "No-line" or "Progressive" lenses. These lenses have a smooth change in focus from the topo of the lens (distance), through the middle (arm's length), to the bottom of the lens (reading distance). We say that there's a "column of clarity", a sweet spot for each working distance for our vision. This column is usually shaped somewhat like an hourglass.

Our favorite Progressive lenses at Skyvision are Varilux products like the Varilux Comfort or the Varilux Physio. We always try to match the strengths of a particular lens to your special visual needs. Our doctors and opticians are experts on making this match. If you are having trouble with reading come on in and learn all about bifocals!