What are bifocal glasses?

What are bifocal glasses?

Bifocal glasses are a type of eyeglasses with dual-focus lenses within a single frame. The eyeframes are designed for both close-up and distance vision. The top part of the bifocal lens is designed for seeing things far away, while the bottom portion helps with reading or close-up tasks.

Similar to bifocals, progressive lenses are another modern alternative to correct near and far vision. Progressive lenses are divided into three smaller parts: Top, Middle, and Bottom. The middle intermediate part is used for intermediate vision, like viewing a computer screen.

So, let's clear things up for you and jargon-bust all the different versions of bifocal lenses. If you are thinking of buying these lenses, then this article is worth your time.

 

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

D Segment Bifocal 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 slightly less dominant than other types of bifocals.

 

Round Segment Bifocal Lens

 Round Segment Bifocal 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

 The Franklin Bifocal 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 a founding father 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 that contains two corrective powers.

Think of these as two lenses in one. The lens features a D-shaped segment at the bottom for near vision, whereas the upper portion is dedicated to distance vision.

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.

This is commonly prescribed for individuals with presbyopia. This is a natural age-related condition where your eyesight gradually loses the ability to focus on nearby objects.

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 Progressive Glasses?

Bifocal and progressive (varifocal) glasses are specially designed to correct multiple vision problems in a single lens. But both are different.

Structure of the Lens

But the main difference lies in the structure of the lens. Bifocal is divided into two distinct sections, whereas varifocals have no visible lines or distinct lens segments. 

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 clearly anything at any distance.

  


Bifocals vs progressive

Adaptation Time

Bifocals are comparatively simpler than varifocals or progressives. Adapting to these glasses is generally easier than adjusting to progressive lenses.

Varifocal lenses (progressives), however, have a larger focal capacity. The trouble is that they can take a while to get used to. But once your eyes adapt to these, they provide a more comfortable and visually satisfying experience.

Visual Experience

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. 

This will provide a smooth and natural visual transition between different distances. 

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

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.

Progressive will give you a smoother and clearer vision throughout different focal length and color contrast.

 

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.

All of our glasses are made from eco-friendly materials. Each lens is designed carefully by us. Visit our online store to find the best glasses for you.

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


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