An Introduction to Bifocal Lenses
What makes bifocal lenses different than other lenses is they have two distinct optical powers. In other words, these lenses are made up of two different lenses that are bonded to each other. One of the parts is called the carrier and it refers to the power for distance viewing while the other lens is called the segment and it is the lens with power to correct your reading problems.
The person credited with the introduction of bifocal lenses was Benjamin Franklin who came up with this kind of lens in the later parts of the eighteenth century. It was only in 1824, that such lenses were given the name of bifocals.
One Pair Instead of Multiple Pairs
Bifocal lenses are primarily used by those who require a single pair to correct two different vision problems. Thus, if you have trouble focusing on objects close to you as well as far from you, then you would benefit enormously by using the bifocals. Mostly, the top part of the lens has the power that corrects the distance vision problems while the bottom part has the power to correct near vision problems.
Different Shapes and Segment Sizes
Bifocal lenses are available with different shapes and segment sizes. The D28 is the most popular type and it gets its name because the segment is shaped like a D and is 28 mm wide. Before you opt for this kind of lenses, it makes sense to learn more about the pros and cons. Here is a brief look at the good and bad of bifocals.
Pros
The biggest advantage offered by bifocals is they offer a stable as well as wide view in each of the two parts of the lens. Second, they are a cheaper option compared to buying multiple glasses. They are also cheaper than varifocals.
Cons
On the downside, is the problem of the power of the lenses changing when your eyes shift their focus from the main part of the lens to the lower part. This has a disconcerting effect on the wearer as there is a rapid increase in power which causes the objects below the eye line almost disappearing from sight or looking blurry.
How to Get the Most Out of Your Bifocals?
If you normally do not move about a lot like when you sit in front of a computer, then bifocal lenses are a very good option because there is hardly any need to move your focus up and down. Even then, you may still have to adjust the position of objects like the monitor and this can cause a slight interference in your vision when you shift your focus to reading the text on the computer screen.
Another thing to note is that when you walk when wearing the bifocals, you will need to practice moving your vision below the eye-line. At first, you will need to exercise care when going up or down a staircase or when traversing curbs.
The bottom line is bifocal lenses are a good option as they allow you to use a single pair for near and distance vision problem correction. Before you choose this kind of eyewear, make sure that you provide your exact prescription and PD measurement.
