mid-distance eyeglass lenses -how to work out Add accurately?

[Mary Crewkerne]

Hi - a quick question about intermediate-distance eyeglass lenses.

My prescription for distance lenses is (R) Sph -1.75, Cyl -1.25 Axis 165, (L) Sph -2.00, Cyl -0.75 Axis 035, and my near Add is +1.25 for both eyes.

I have bought distance glasses and reading glasses. My usual distance for reading books is ~ 35-40cm (14-16"). The reading glasses are fine for reading, but things start to blur fast at greater distances than 18 inches. My usual distance for reading a computer screen is ~ 55-60cm (22-24"). So I'm thinking of getting some intermediate-distance lenses.

The 'usual' intermediate Add is half the near Add. But is it possible to be more accurate than this, given the actual distances involved?

(I also have to say - I'm not sure why the usual Intermediate correction is the arithmetic mean of the values for Distance and Near, given that the Sph and Cyl figures are in dioptres, where 1 dioptre is 1/metre - so I would have guessed the harmonic mean would be a better mean, but that's another discussion!)

Thanks for any help with this!

Mary

[Dave Plowman (News)]

Since you have astigmatism, ready made reading glasses won't be suitable. So as they'll have to be made up by an optician, get a test at the distance you're concerned with?

I wear contact lenses which correct my eyes for distance, and find +1 ready made ideal for the computer.

[dennis]

Have you tried varifocals yet? they have a zone for intermediate as well as for reading. just make sure the optician knows that the intermediate is for a screen and not for TV viewing. Of course some people can still focus over a good range but it gets less as you get older.

[Mary Crewkerne]

"Dave Plowman (News)" wrote in news: [e-mail]:

They won't be ready-made; I'm too lop-sided! :) I'm planning to get the lenses mail order from Glasses Direct, who can put new lenses into old frames for £25 - you just tell them the figures you need.

Usually apparently the Intermediate addition is half the Near addition. but that's very rough, given that some people need intermediate glasses for seeing e.g. people's faces etc. at say 3ft, whereas others need them for computer screens etc..

Any idea what % of your "near" Addition that corresponds to?

You probably already know this, but:

Distance: Sph x Near addition: y

->

Reading: Sph x+y "Standard" intermediate: Sph x + (y/2)

Mary

[Mary Crewkerne]

"dennis@home" wrote in news:j1jbc9$ubl$ [e-mail]:

No but I've tried bifocals and prefer to have the whole lens available. I don't mind switching glasses all the time. Had a test in Tesco and the optician handed me over to a salesman who made a hard sell effort to sell me varifocals, not on the basis of any specific need (other than I've got eyesight typical for my age) but just because they were "convenient". I said most people I've known who've had them haven't got on with them, at which point he said if I paid £50 extra I could get higher-range varifocals in which the often blurred areas at the sides would be smaller!

[Huge]

Selection error. The only people you know not to have got on with them are those who complained about them.

[Mary Crewkerne]

Huge wrote in news: [e-mail]:

Not so - three family members and three friends of 30 years. All apart from two hadn't told me anything about them until I asked. I also asked five other people whether they'd ever used varifocals, who said no.

I have nothing against varifocals and am sure they work very well for some people, and are what some people prefer.

But even if they worked fine for everyone, I'd still prefer separate pairs of glasses - that's just me :-)

Mary

[chris French]

Indeed.

Certainly, some people don't seem to get on with them, but I think it's something you have to try yourself really. most people wouldn't know I had varifocals, as I've no reason to mention it, they just work.

I got my first varifocals about a year ago, and I've had no problem with them at all. When I first put them on there was a bit of a 'Oooo, that a bit odd' moment, but my eyes adjusted in a couple of minutes (I get the same sort of thing if I put my single vision specs on for a bit - but it goes after about a minute) I did get the more expensive lenses, rather than the bog standard ones, but there are no 'blurred' areas etc. as such. The only time I notice that they are varifocals is in the odd occasion I look through the 'wrong' bit of the lense.

Typically working close over head through the distance bit, or watching the TV lying down through the near vision bit.

Certainly much more convenient than having to swap glasses around though

[polygonum]

Mary,

I have astigmatism combined with short sightedness. About a year or so ago I found my work was getting very much more difficult simply due to inability to focus so well on the computer monitors. My company sent me for a sight test and I got a pair of special glasses. The company paid and the glasses helped.

And then I was diagnosed hypothyroid. More importantly I starting taking thyroxine. Since then I have stopped using the special glasses and am able to wear my normal distance glasses almost all the time. Occasionally I work for a while without any glasses.

I find my focussing has very significantly improved. Although I could wear the special glasses, I never did like the fact that when wearing them, simply looking up (out of the window or at a colleague a few metres away) was unpleasant.

Having just had another test I find that the measurements have only changed a tiny bit - but my ability to see have improved considerably.

Other improvements in sight have included far better tolerance of bright lights (e.g. oncoming headlamps), better low light vision, fewer 'floaters', and greater eye comfort.

This probably will not apply to you, but thought it worth mentioning.

[<me9]

I just gave my optician the distance I wanted them for and she gave the appropriate addition (checking it with me on her machine), which happens to be +1.25, ie a focal length of 80 cm. My reading addition is +2.25.

[Harry Bloomfield]

Mary Crewkerne was thinking very hard :

You can add me to the list too, I found them useless for the purpose and down right dangerous to walk about wearing.

I can walk about fine in any of the pairs I wear for reading, TV and driving, but I struggled in the varifocals - constantly bumping into things below eye level. The close focus bit at the bottom was also useless for reading, involving head movement rather than eye movement along a line of text.

[Newshound]

I'm on my second set (standard, not "expensive") and find them excellent. I was given a set of bifocal safety glasses which I found hopeless. But I have a single prescription set for computer work: I find the "computer distance" zone in varifocals is too small and in the wrong place. I find I can work with paper and on a screen at the same time.

So, what Chris says. Not having to swap for everyday life (driving, TV, close up work) but switching to the computer glasses for computers works for me. Never tried Tescos; used to use one of the big "old" chains, but found their hard sell of "specials" a bit much on top of their prices. Went to Vision Express once (OK) and SpecSavers twice. If anything, SpecSavers are a bit too ready *not* to suggest the extras (hard coatings, etc).

[Lobster]

I've just been to get my eyes tested again (I'm very shortsighted) particularly as I'm now having difficulty reading and have been pointed in the direction of varifocals by the optician. Certainly sounds an attractive option as I can't abide the prospect of carrying round different specs all the time; however when I saw the price (many hundreds of £) I panicked and fled the opticians to go home and try for the safety of glassesdirect.com etc.

Would be good to hear more opinions on whether they are worth getting?

The other thing was that the optician's fitter presented a lot of options for different varifocal lenses at massively different prices, but didn't seem to have a particularly clear idea of what you got for your money, which were to me reinforced by the leaflets she gave me (anyone for snake oil?) eg:

(or

(or

The varifocals from selectspecs.com and glassesdirect.com are massively cheaper than the hight street - you don't get any option for different flavours of varifocals. I've used these outlets before and found them fine except for some difficulties with correct frame fitting: anyone tried them for varifocals?

David

[polygonum]

My experiences of

have been excellent - but= , =

unfortunately for you, not tried them for varifocals. But they do list =

them and have been very helpful in terms of advice and email "discussion= ".

As usual, no relationship except as a satisfied customer...

[polygonum]

My experiences of

have been excellent - but= , =

unfortunately for you, not tried them for varifocals. But they do list =

them and have been very helpful in terms of advice and email "discussion= ".

As usual, no relationship except as a satisfied customer...

[dennis]

How bad is your prescription? Asda do varifocals for about £80 with 1.7 index lenses if you have high powers..

Bloody hell, glassesdirect are more expensive than the optician I use and way more expensive than Asda where I have just been. Why would you use them rather than someone you can talk to in a shop?

[Bob Eager]

One would hope that all opticians produce good prescriptions.

[Dave Liquorice]

Got varifocals a couple of years back, like Mr French a few "ooo that's weird" moments when I first got 'em but that stopped after a hour or so. It is rather disconcerting, the world in the lower section of your field of vision "moves" differently to the rest of the world. I can well see people not liking it but at -5 my brain is well used to a world that changes shape as my head moves. Things are decidedly barrel shaped in the extremes of my vision field but straight in the middle.

The only thing that I find annoying is reading small print on shelf edge labels, get close enough for the print to be big enough and I have put my head back to look through the bottom section to bring the print to focus. Normal reading is fine as the natural position for reading material is below your eye line.

I'm not sure I would buy varifocals online, the position of the lens in relation to your eye is much more important with varifocals than with single vision lenses. I sometimes wonder if those that "don't get on" with varifocals simply have an incorrect fit/alignment.

[chris French]

I don't get any of that with mine at all. That might be because of my prescription not having to vary to much across the lenses or the type of lenses. If I put my old single vision ones back on then I do get the world at the bottom of the lenses doing weird things when I move my head

Yup, I certainly don't think I'd want to get the first pair online

[chris French]

Yup. I put up with finding it gradually more difficult reading smaller print, and in poorer light, but eventually you have to bite the bullet.

it seems you can split it into those of us who like them, and those who don't :-)

I think the only way is to try them out for yourself.

Specsavers (and presumably some other places) will replace your varifocals with bifocals or 2 pairs of single vision glasses (and refund the difference in price) within 30 days if you don't get on with them.

I'd not say it was snake oil, but as with most things, there is a law of diminishing returns.

AIUI basically, the more expensive lenses manage the transitions between the prescriptions more smoothly, have a wider area of clear vision, and less soft focus areas around the edge of the vision.

Like most things, as you go up the price range I think the extra benefits get less as you go up. But of course if you are seeling a brand like Varilux, you need to keep finding things to encourage people to pay more for yours :-)

FWIW I had the 'tailor made' lenses from Specsavers - currently £159 (eeek!) for the lenses. The optician suggested that with my prescription I would find them better, and I also wanted to give myself the chance to have the best experience with them. Have to say I'm very happy with them. I don't notice any soft focus areas, or have any weird affects from the transition

I felt much happier getting them from an opticians. The lense position etc. is important, and if I had any issues it gave me somewhere to go back too. I'm considering though getting a cheaper lenses online for a spare apir and to see how it compares to my existing lenses