If you have been a specs wearing person, you are bound to have a different kind of problem once you reach middle age, say, the age of 45. Reading books or newspapers would become difficult for most people after this age, sometimes even earlier. Reading glasses are the obvious option, but as said, if you are wearing glasses already, for far-sightedness, then it becomes haphazard to use two sets of specs at the same time. The answer to that – BIFOCALS.
Bifocals were invented, yes, practically made up by the great American statesman, Benjamin Franklin. Franklin, as the story goes, had two sets of glasses, one for far sightedness (seeing objects at a distance) and another for reading. Busy man as he was, he got tired of using and juggling two pairs continuously. He came up with an idea that was to going to change specs wearing for ever – he cut off his lenses in two parts, after that, combined one half of his reading lens to another half of his long distance seeing lens to form ONE SINGLE LENS FOR EACH FRAME. Thus was born the bifocal.
The bifocal lens as Franklin used it, was actually divided into two parts, with a distinct border line between the two. These are still in use today, and are known by his name, as Franklin lenses, or as Executive lenses (“E” lenses). However, nowadays, ‘progressive’ lenses are available, where the line is invisible.
Bifocal lenses are made of two parts – a lower part which helps in reading, and the other part which helps to see long distance, things at a distance. This design is because people read with the book held down, and we normally look up when looking at things.
Note- These lenses can also be used only as reading lenses. In that case, the upper part of the lenses does not have any power. As far as the bifocals are concerned, there are basically four types of designs with which the reading lens part is embedded within the full lens:
o Round part at the lower side of the lens.
o Semi circle, also known as slanted D, or half moon.
o ‘Ribbon’ segment – a very small rectangular portion along the lower part of the glass.
o Finally, the Franklin lens, which we have already discussed.
No matter what type of reading lens feature you choose to incorporate, do keep in mind that ALL BIFOCALS WORK ON THE SAME PRINCIPLE. The lower half is for reading and the upper half is for looking at distant things. Bifocals are very useful things; the best part about them is that practice, it gets better. You would soon get into the habit of reading and looking from different parts of the lens, and after a few months or so it will become instinctive.
So now, you can safely get rid of those two sets of specs which have been so cumbersome. Or even better, if you already have them, why throw them away? Take them to an optician, and ask her/him to design you a pair of Benjamin Franklin lenses! If the person seems unconvinced, you can always come up with the story we told you!