Bifocals Vs Varifocals

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Bifocals V Varifocals

This is a real heavyweight head to head. These are the 2 main types of lenses that let you see both distance and near when you have started to loose your natural ability to focus up-close (presbyopia).

Why we need them

Unfortunately we naturally loose our ability to focus onto things up-close as we age, for most of us this will happen at some time in our 40s. It's called presbyopia. This is when we start to need reading glasses. 

These reading glasses are only useful for things close to us, the further away something is with reading glasses the more blurred it becomes/

It can become a real pain to have to change from your distance glasses to your reading glasses, or even no glasses to reading glasses. This is when Bifocals and Varifocals are useful, when you need a different power for distance and reading.

They both have a distance and near vision section - but which is best?  Which should you be buying?

This is going to give you the information to help you make your choice of which is best for you. (Spoiler alert - I have my favourite, you'll see at the end).

How they work

Both Bifocals and Varifocals have different powers in the lenses at different parts of the lens - Bifocals are the ones with the line across across and a small section of reading power in a "reading segment".

The Varifocal gradually changes the power down the lens, so you don't see any lines or joins, it looks just like a normal plain spectacle lens. Therefore,  the cosmetic appearance is better in Varifocals. 

One point to the Varifocals.

The Jewellers window effect  

This explains a limitation of the vision in a Bifocal. The easiest way to describe it is the Jewellers window effect. If you look into a jewellers window and want to see the price of the ring right at the back it's too close to see with the distance part of the Bifocal but you can't get close enough to use the bifocal segment because the window is in the way! 

This is because the Bifocal has only one close focal point set for normal reading. (Ok, you can have Bifocals with the near set to a different specific distance but most are set for a normal reading distance of around 35 to 45 cm).

The Varifocal wins here again because as it changes power down the lens you get vision at all the different distances from the far distance to the close reading. 

 Limitations in the vision

As you move down the Bifocal lens, you suddenly hit the full near vision power. This can have the effect of whatever you are looking at to suddenly jump up in front of you. It can be a little strange but you do get used to it.

The Varifocal on the other hand smoothly changes it's power so you don't get a sudden jump in the vision, things stay where they are.

As you move down the power in the Varifocal this change in the curvature can create a distortion. It's because physics doesn't like those changes down the lens and varifocals have to be designed to minimise these distorted or blurred areas of vision. (If you have a look at some of our other things about Varifocals you'll see that it's the design of the lens that is the most important aspect of a Varifocal). The Bifocal doesn't have this problem with distortion - the segment of near power is added into the lens so there is no changing curvature for physics to worry about. This means you don't get the peripheral distortions you can get in a Varifocal - a point to the Bifocals!

This does mean that for some people adaptation to a Bifocal may be easier than a Varifocal.

They do both have the same limitation of vision if you look down through the bottom of the lens - the reading part - the floor will be blurred. This means you have to be careful on steps and curbs until you have got used to it.

Technology and variations

Bifocals are much older technology compared to Varifocals. This means that it's getting harder to get different types of Bifocal because no manufacturers are investing in making them. Varifocals are much newer technology and are constantly evolving to get better and better, they are available in much more options such as thinner lenses, different colours in photochromic (colour changing lenses in sunlight), blue light filtering lenses and even new LED lenses for night time driving.

This range of options just aren't available in Bifocals. 

I think you can see which my winner is - yes, it's the Varifocals! I personally wear Varifocals every day and find them amazing. There are certain circumstances and times when Bifocals are a better option - you'll need to take your Optometrist or Dispensing Opticians advice.

I do hope this has been helpful!