Progressive lens: the invisible bifocal
Blog vol 3. 29. Progressive lens, the invisible bifocal
A French lens company, Essilor, started to roll out the first progessive, or no-line bifocal, into the market sixty years ago. An engineer by trade, Bernard Maitenaz, was instrumental in developing the first Varilux lens.
Before that time, all bifocal lenses had some form of line to demarcate the different areas of power in the lens. Ben Franklin, the early American scientist and statesman, developed the first bifocal by cutting in half two lenses of different powers, and putting them to together in one frame. He wanted to have the distance vision clear and then have a larger power in the bottom for reading, so in 1784 he came up with “double spectacles”, a really helpful innovation especially for people with distance prescriptions.
Now, no one needs to know, shhh!, if you are wearing bifocals or not.
No fussing around with reading glasses, or trying to find a pair - where did I put them? Or having to ask the grandkids to read the menu for you.
The no-line bifocal, or progressive lens, has improved dramatically over the years, as lens materials and lens production has changed. The first progressive was a lens that had a set power on the front surface and then the patient’s prescription would be ground on the back. Recent developments in CNC (Computerized Numerical Control) make it possible for the front and back surfaces to both be worked on. Now, custom measurements, like pantoscopic tilt, frame wrap, vertex distance, and variable insets are measured to inform the diamond cutters on the best possible customized progressive. These custom lenses widen out the usable zone for distance, computer, and near viewing.
At Burlington Eyecare, we use a lot of Nikon optical lenses for their excellent quality and state of the art technology. One lens design in particular, the SeeMax Ultimate, is a progressive lens that is completely individualized. In the past, conventional progressives were made with one design concept, whereas this new Nikon progressive is made from 428,793,740 different design possibilities! (Read more about SeeMax Ultimate here).
All of our bifocal-wearing employees at Burlington Eyecare wear the Ultimate and can attest to the wider zones for all their viewing and the general comfort of the lens. Since it is customized, the Ultimate is more expensive than the standard progressive. The standard progressive is still an excellent choice, but the Ultimate, if you can swing it, is a great way to go.
What a great development the progressive lens is! I love mine, so glad to not have to wear the old lined bifocal. It will be interesting to see where spectacle lens development goes from here.
til next week,
the good doctor
