What are bifocal glasses?

What are bifocal glasses?

All these lens types.

So many names right?

What are bifocal glasses? What are progressives?

We wanted to clear things up for you and jargon-bust all the different versions of bifocal lenses.

If you’re researching different lens types, this article should make things easier to understand.


Table of contents

Types of bifocal lenses
What is the purpose of bifocal glasses? 
What is the difference between bifocal and varifocal glasses? 
Bifocals vs progressive 
Do I need bifocal glasses?
Bifocal glasses for driving


Types of bifocal lenses


D_Segment Bifocal Lens

What are bifocal glasses? D Segment Lens

Also known as a ‘straight-top’ or ‘flat-top’ section, this type of bifocal lens has a D shaped segment (“seg” for short.)

The D-seg is positioned in the lower section of the lens and blends relatively well into the lower half of the lens. Like all bifocals, this small segment is responsible for correcting close-reading within 35cm.

This type of lens is very popular and is slightly less dominant than other types of bifocals.


Round Segment Bifocal Lens

What are bifocal glasses? Round Segment Lens

The “round-seg” bifocal lens is fairly self-explanatory. The corrective segment is round in shape, intersected by the bottom periphery of the lens. Generally, this segment is never a full circle and isn’t quite as popular as other bifocal types.


The Franklin Bifocal Lens

What are bifocal glasses? Franklin Lens

These bifocal lenses are usually called “executive bifocals” but we couldn’t resist telling you the story of how these lenses came to be.

Besides the challenge of being president, Benjamin Franklin had difficulty with his near and distance viewing. Cleverly, he took two lenses, one for close reading, one for distance and proceeded to cut them both in half to fit into his spectacles.

Today, the Franklin or executive lens is made of just one lens but still bears the defining split line across the front of the lens.

This is another popular lens type and has the most dominant close-reading lens section.


Benjamin Franklin invented Bifocal Glasses

What is the purpose of bifocal glasses?

Bifocals are a multifocal lens which contains two corrective powers.

Think of these as two lenses in one. This type of lens is characterised by it’s defining ‘split’ or ‘D’ section in the bottom half of the lens.

This small window-section provides close-reading correction for the symptoms of long-sightedness (hyperopia.) Close-reading, within 35cm, can be corrected by looking through the D shaped segment within the lens.

The larger, main portion of the lens is used for correcting distance vision. Otherwise known as short-sightedness (myopia) looking at far-away objects such as road signs or the far side of a room can be corrected.

The bifocal glasses meaning is defined by the dual-purpose nature of these two lens sections.


What is the difference between bifocal and varifocal glasses

What is the difference between bifocal and varifocal glasses?

So we know that bifocals have two lens sections.

But get this; varifocals have no definitive lens sections.

Instead, these ‘super lenses’ have an entire spectrum of corrective power.

Between the close reading power at the bottom of the lens and the distance power at the top of the lens, you can visually find the right focal point to see pretty much anything at any distance.


Bifocals vs progressive

Bifocals vs progressive?

This is really about preference.

Bifocals are comparatively simpler than varifocals. You could go as far as saying they’re a bit two dimensional.

Varifocal lenses (progressives) however have a larger focal capacity. The trouble is that they can take a while to get used to.

The difference between these lenses is somewhat of a debate. A good way to decide between these lens types depends on your lifestyle and how you use your glasses the most.

Bifocals are great for daily life if you still have good intermediate sight. You can benefit from the near and far corrective power without the disorientation that some people experience from progressive lenses.

Varifocals, on the other hand, are perhaps a better option if you’d benefit from all three corrective powers. If your eyesight is deteriorating in close, intermediate and distance, progressive lenses are inevitably the best option for you.

The next time you visit your optician, you should ask them which lens they’d most recommend.

You can order either type of lens using our lens menu.


Do I need bifocal glasses

Do I need bifocal glasses?

After the age of 40, your eye muscles will have begun to weaken. These are the muscles used to contract the soft crystalline lens in your eye.

Over time, your eye-lens also simultaneously stiffens. This common condition is known as presbyopia and makes close-reading more difficult.

If you already wear glasses but are beginning to struggle with close-reading, you may well need bifocal glasses. 


Man behind the wheel of a car

Bifocal glasses for driving

Using bifocal glasses is a great way to avoid having two separate pairs of spectacle frames. Each bifocal lens has two corrective powers which give you the benefit of distance and close-reading prescriptions.

As you drive, your shifts in focus can be accommodated by your bifocal lenses. Arguably, progressive (varifocal) lenses provide a greater focal capacity but this depends on your preference when it comes to multifocal lenses.


Bifocal glasses being made in the UK

Bifocal glasses uk

At Banton Frameworks, we handmade our luxury acetate frames right here in the UK. Inside our Glasgow-based workshop, we proudly produce our collection of bifocal glasses frames using the best materials and processes.

Hopefully you found this article helpful. Please check out our other eyecare blogs. Thanks for stopping by.