Varifocal specifications 11 November 2022 at 2:53PM in Health & beauty MoneySaving 6 replies 231 views

MildMellow

I have reached that age where I need reading glasses. The optician recommends varifocals, but I'm strugging to understand the differences between the different types.

Specsavers use terms like "wider field of clear vision", "a wide field of clear vision" and "our widest field of clear vision". Glasses Direct say "enhance your field of vision ... by 30%, which is at least a number but they don't say what of. Nobody gives actual specifications for what this field of vision is, and how the more expensive options compare to each other.

For example I think the lenses Specsavers have sold me have a distance vision cone of roughly 25 degrees (measured using a tape measure and some trig), which is not enough to cover a 28inch computer screen at 1m. The transition seems to start a few degrees above horizontal. I'd be willing to pay for that to be, say, 45 degrees.

I'd like to have some objective metrics to compare "Standard", "Premium", "Elite", "Supreme", "Easy2Max", Amplitude Plus" and "Progressive Plus 2" etc. other than just price!

I've looked at the previous threads and there seemed to be some knowledgable people here in 2009, so I thought it worth asking please.

Thanks.

Undervalued

MildMellow said:

I have reached that age where I need reading glasses. The optician recommends varifocals, but I'm strugging to understand the differences between the different types.

Specsavers use terms like "wider field of clear vision", "a wide field of clear vision" and "our widest field of clear vision". Glasses Direct say "enhance your field of vision ... by 30%, which is at least a number but they don't say what of. Nobody gives actual specifications for what this field of vision is, and how the more expensive options compare to each other.

For example I think the lenses Specsavers have sold me have a distance vision cone of roughly 25 degrees (measured using a tape measure and some trig), which is not enough to cover a 28inch computer screen at 1m. The transition seems to start a few degrees above horizontal. I'd be willing to pay for that to be, say, 45 degrees.

I'd like to have some objective metrics to compare "Standard", "Premium", "Elite", "Supreme", "Easy2Max", Amplitude Plus" and "Progressive Plus 2" etc. other than just price!

I've looked at the previous threads and there seemed to be some knowledgable people here in 2009, so I thought it worth asking please.

Thanks.

Before one gets too far into the technicalities, a lot depends on your prescription and how well the glasses are positioned.

Firstly, if your eyes are roughly equal and you are mildly short sighted, plus are now reaching the common middle aged problem of your arms not be long enough to read comfortably (!) it is relatively easy.

However, if you are very significantly short sighted, have lots of astigmatism and maybe have a big difference between your two eyes then it is more of a challenge.

The measurements you talk about are only partially relevant because it does also depend on how much and how easily you subconsciously adjust by moving your head.

All varifocals suffer to some extent with distortion if you glance sideway with your eyes without turning your head. The geometry of the lenses is very complex and the more expensive ones minimise this (although cannot eliminate the problem entirely). However there is a trade-off in doing this, sometimes in narrowing the mid distance part of the lens. Depending on your use (and mindset) this is not always an advantage.

As a start, have you experimented with very small adjustments in how high or low the glasses sit?

Just to add, I am not an optician but I do have a reasonably detailed understanding of optics from my work. I wear varifocals, despite having a unusual prescription. I normally have my eyes tested at the training clinic, at one of the universities that teach optometrists, so get to discuss the problem in detail with their supervisors.

kirtondm

All varifocals will compromise vision. Generally the biggest compromise will be for Computer distance at 1m. They are defintely not the best option for this. If you do a lot of computer work you are better off with either a pair focused exlusively at 1m or an 'office' type pair or Intermediate / near bifocal.

The main advantage of varifocals is flexibility you will not need to swop spectacles. They will not be as good for distance vision as distance specs , they will not be as good for VDU as VDU specs they will not be as good for reading as reading specs.

If you want 100% of you distance vision preserved then the answer would be a bifocal altough you can only pick 1 focus for the near vision with this.

I have a couple of patients still in trifocals which would give you perfect visual field at distance / intemediate and near but this are not cosmetically popular these days.

I would suggest the only way of knowing whether varifocals will work for you is to try them. If you do want the exact figures on clear visual field width these are normally available from higher end manufactures' such as nikon etc but not in my opinion a substitute for  a practical trial. most opticians will offer a non tolerance guarantee on mid level or higher varificoals which is probably the place to start.

PoGee

Before varifocals, the lens of choice was the executive bifocal. Don't know if they are still manufactured, though.

kirtondm

They are I still supply exec Bifs  to patients

hollie.weimeraner

I use a computer every day and have had Zeiss varifocal lenses and never had an issue.  They're not cheap though.

Manxman_in_exile

I suppose it depends how complicated your prescription is, but I've never got on with varifocals and always found the effect quite disconcerting when moving my head.

But I do a lot of reading and what annoyed me most was that to make full use of the "reading" part of the lens, I found myself having to look down my nose in a very unnatural and uncomfortable position for my eyes.

I actually use three pairs of glasses and (despite my optician's expressed surprise) have no difficulty swapping between them.

But I suspect my prescription is pretty straightforward.  I have a prescription pair for distance vision and two off-the-shelf supermarket pairs, one for reading (2x mag) and another for computer work (1.5x mag).