The design of bifocal lenses depends on what is chosen by you. In this article, you will find out what bifocal lens designs are available and what to consider.
The traditional older bifocal lenses will have a visible line that separates the part for distance vision from the part with the reading support. However, there are also no-line bifocal lenses available and we will get to them after we described the traditional options.
Different Bifocal Lens Designs Explained
Bifocal lens designs are available in a variety of shapes. Those shapes are influenced by the reading segment. It can be chosen in a round or flat shape and it comes in different sizes. Depending on your daily activities you can match them to your needs.
The reading segment can also be manufactured in different ways. This means you can get your bifocal lenses with a ledge or no ledge. Having no ledge is definitely a benefit because it is easier to clean without the ledge on the lens surface.
There are three options out there and those are presented in the picture down below. All options are illustrated by a view from the side.
But now lets have a closer look at the shapes of the reading segments. In most cases they have a standard width of 25 up to 28mm. However they can be as wide as the width of your chosen frame.
The Options in Bifocal Lenses With the Different Reading Segments
Depending on your wishes and requirements there is a variety of reading segments available. For example, if you wish to see the stairs clearly while looking down on them you could do so with a B Ribbon Segment for example.
If you use the space under the reading segment you can see clearly further away. But of course, the field of view will get minimized with this solution.
We already talked about the ledge in plastic bifocal lenses before. Depending on the sitze of the reading segment you will get a bigger or smaller ledge. A bigger reading segment will also lead to a bigger ledge.
If you wish to expand your field of view while reading you can maximize the size of your reading segment with a Franklin bifocal lens or a very big round reading segment.
Can You Get Bifocals Without Lines?
Yes, bifocal lenses without visible lines are available. However the options are a little bit more limited. You can choose from bigger or smaller round lens segments. On the sides of the reading segments the field of view will be clear again for distance vision.
An exception to this rule is the Shamir Duo. It is also advertised as an Bifocal lens without a visible line but the periphery (right and left) in the lower half will be blurry. More comparable to a progressive lens design.
If you want to order a bifocal lens without lines you should use the following names:
- Free Form Bifocals
- Blended Bifocals
Do not use the term no-line bifocals if you want to buy bifocals. The reason is this term gets often mixed up with progressive lenses.
Bifocal Lenses Advantages & Disadvantages
The Advantages of Bifocal Lenses
- The field of view in the reading space is very customizable in terms of shape and its position
- There is no blur (no surface astigmatism) compared to progressive lenses
- the adaptation process is usually a bit shorter compared to progressive lenses
The Disadvantages of Bifocal Lenses
- In most progressive lenses you will have an image jump when switching from distance to near vision. You do not have this with progressive lenses
- They are not as aesthetically appealing as other lenses without the line
- If you have an Add value (like 2,50D) You might end up with a blurry mid-distance. In such a case a trifocal lens would be the solution
Bifocal Lenses Alternatives
There are a lot of alternatives when it comes to bifocal lenses. Here is a list of them.
- progressive lenses
- trifocal lenses
- multifocal contact lenses
- bifocal contact lenses
- Intraocular lenses
Do I Really Need Bifocals?
You need bifocals if you do not want to switch between single vision glasses for the distance and reading all the time. Usually people are in the mid 40s when it gets time for bifocals.
In such a case a basic eye test at your local optical can reveal if you need bifocals. The optician or optometrist will measure your prescription for the distance. Then you can read with this lens power holding the text in your hands.
If you look at the text and it gets way sharper when the optician adds more lens power to the testing frame it is the right time for you to get bifocals. Of course, you can decide in the end if there is a need for you to get both lens powers in one frame.
For most people, it is very convenient not having to grab your reading lenses to get a clear look at the text. Most wearers of bifocals want it clear immediately. That is the big benefit of bifocals. But if you are fine with switching glasses you do not need bifocals. Because the process already works for you.
Can I Wear Bifocals All the Time?
Yes, you can wear bifocals all the time if you are able to maintain your natural posture while going through your daily routines.
Bifocals are designed to give you an extremely wide field of view when it comes to distance vision when you stay upright and just look in front of you. As you perform eye movements down you will get to the part of the bifocals with the added lens power which enables you to see more clearly a distance closer to you.
However if you want to focus on a PC Screen in front of you you have no support for reading in this distance whatsoever because you are using the upper half of the lens. And there is just the lens power for the distance.
In such a situation some people will extend there necks and place there chin in an unnatural high position. In such a case you are looking through the lower part of the lens with the reading support. But in such a case problems might come up with your neck and shoulders with time.
If you need to leave your natural posture in order to see the screen clearly you would have to switch to another pair of glasses for this task. But if you are able to stay in a natural posture all the time you can wear your bifocals all the time.
I wish you a great day.