What Are Bifocals & Do You Need Them?
Olivia De Santos
Are you tired of squinting to read your favorite book, or finding it harder to see road signs? Or, do both of these apply to you?
If you answered yes to all of the above, bifocals could be what you’re looking for. But before that, what are bifocals, and are they the right type of glasses for you? Read on to find out.
What are bifocals?
Let’s start with the basics. Bifocals are a type of glasses or contact lens that have two prescriptions in the same lens. ‘Bi’ means two, and ‘focals’ refers to the focus of the lens.
Typically, bifocals have two zones. The bottom half is for near vision. Think reading, writing, knitting – any kind of close, focused viewing.
The top half or outer ring of your lenses is dedicated to distance vision. That means road signs, movie screens and identifying approaching blobs as actual people with faces!
Apart from differing prescriptions, each segment of the lenses are shaped differently as well.
If you need two prescriptions for your glasses, you most likely have presbyopia. Common in older adults, the condition is caused by your eyes’ natural aging process. As we grow older, our lenses inside our eyes begin to thicken and harden, making them less flexible and impairing our near vision.
Luckily, bifocals have been around for centuries. In fact, the Founding Father of the US, Benjamin Franklin himself is credited with the invention of bifocal lenses in the 1800s.
Other than that, people like athletes and medical professionals are also great candidates for bifocals. These are called occupational bifocals and specifically tailored to suit the wearer’s designated tasks.
Now, let’s dive a little deeper.
Types of bifocal lenses
In the previous section, we mentioned that the top half of your bifocals is for distance vision and the bottom half is for near vision. However, that’s kind of a half-truth. There are a few types of bifocals that are defined by how the two sections of the lenses are shaped. Confused? Let’s break it down:
The bifocals we described earlier are specifically known as executive bifocals. These have a clear line straight across the lens dividing the two prescriptions. The top half helps you to see far away and the bottom half helps you see up close.
Half moon/flat-top/D segment
For these bifocals, the near vision segment looks like a capital D with the straight side pointing upwards. This segment is located towards the bottom of the lens but doesn’t take up the entire bottom half like in executive bifocals. Instead, it floats. The distance vision part of the lens takes up the half-moon segment.
A round segment bifocal appears like a circle within the lens. The circle houses the near vision segment of the lens. Like in the half-moon bifocals, the near vision/round segment floats toward the lower center of the lens.
A ribbon segment bifocal lens has a center band straight across the lens for the near vision prescription. The distance vision segment is housed above and below the ribbon.
What’s the difference between bifocals and progressives?
If you’ve discussed bifocals with your optometrist, you may have heard of the term “progressive lenses”. Are they the same thing? Not quite.
Bifocals have a definite demarcation between the near vision and distance vision segments of the lens. You can even see the line clearly on the glasses.
Progressives or multifocal lenses have a smoother transition between multiple prescriptions. There are more degrees of vision within the glasses, enabling you to switch between different visions more seamlessly.
Progressive lenses combine distance vision, intermediate vision, and near vision, going in that order from top to bottom. Intermediate vision is necessary for computer usage, watching TV and conducting other day-to-day activities that are neither close up nor far away.
Some people prefer progressives as they are easier to adjust to, compared to bifocals where the switch is more apparent. For others, the defined lines in bifocals make it easier to know where to look through the lens for the type of vision correction you need.
Pros and cons of bifocals
To help you decide, let’s discuss the pros and cons of bifocal lenses.
Pros of bifocals
- You can tackle nearsightedness and farsightedness at the same time without changing glasses. They’re perfect when you’re on the go.
- Bifocals’ near vision segment helps you to read, thus reducing eye strain.
- Bifocals can correct your vision overall. If you have myopia (nearsightedness), the specialized lenses will reduce any stress or strain on your eye muscles that may worsen your vision.
- Depending on your preference, you may find the distinction between the near vision and distance vision segments easier to navigate than progressives. This is because your eyes can adapt to looking through a specific section subconsciously according to your needs.
Cons of bifocals
- You might not enjoy the look of the line between the two prescriptions on your glasses.
- The transition from the distance vision segment to the near vision segment and vice versa can be overly obvious and disorienting for some, especially at the beginning.
- The image you see through one part of the lens and the other are vastly different, which can cause image distortion until you get used to it. This is called image jump or image displacement.
- Unlike with progressives, there is no intermediate vision section in bifocal lenses. If you want an intermediate part in your glasses to bridge the gap between the near vision and distance vision segments, trifocals or progressives may be a better fit for you.
How do bifocals compare to reading glasses?
It’s easy to get reading glasses and bifocals mixed up. Bifocals are often described as lenses to help you read better since the near vision segment of your glasses do exactly that.
Nonetheless, there are a few key differences between reading glasses and bifocals:
- Reading glasses can only help with presbyopia as they are used to magnify text on a page or device. Their lenses are known as single vision lenses. Bifocal lenses can correct both near vision and distance vision.
- You can wear bifocals all day. Reading glasses are generally only worn during tasks in need of near vision like reading and sewing.
- Some ready-made reading glasses are available at drugstores and not just specialist eye care stores. Bifocals, on the other hand, require a prescription.
- Beyond glasses, bifocal lenses can be applied to contact lenses too.
So, are bifocals right for you?
If you find that both your near vision and distance vision are deteriorating and want to avoid the hassle of switching glasses throughout your day, bifocals could be the right fit for you.
However, if you want a more seamless transition between different corrective prescriptions on your lenses, you might prefer multifocal or progressive lenses.
To weigh your options, it’s best to book a consultation with an optometrist so you can try both on for yourself and get expert advice.
Not totally sure if you need glasses in the first place? Check out this guide to see if you have any of the nine signs that indicate yes.
Olivia De Santos