New glasses - issues with lens thickness +ve prescription
Discussion
I'd be very interested to hear from dispensing opticians or others in the trade on the puzzling situation I face. I need to find someone else to reglaze my frames after my existing optician (within an unnamed warehouse-type-store) has been unable to match their previous very satisfactory results, but I would appreciate some advice before I start calling around the local independents. A picture paints a thousand words and all that, so lets get on to the problem;
Two pairs of glasses from the same shop, one made in 2013 and the other brand new this week. Identical frames, apparently identical lenses (Zeiss 1.6 index), with what feels like a very small bump in prescription, has resulted in a dramatic change in lens thickness, to the extent that the optician was as surprised as I - but was ultimately unable to get a satisfactory answer out of Zeiss.
At the bottom of the photo you will see my original 2013 glasses - lens edge thickness is in the range of 2 - 2.2mm all around, in fact centre not much different either. Lenses fit the frames very well indeed.
2018 at the top - edge thickness has more than doubled, between 4.6 - 5mm and so presents very poorly in the same frame, more than double the lens weight, etc.
Prescriptions are as follows;
2013:
2018:
I'd be grateful for any insight! As far as I can see, my 2013 left lens is actually a higher power & cylinder than the new right lens, yet we still see a uniform >2x increase in thickness!
The store claim the same blank sizes were used (70mm). Apparently Zeiss 'Optima' was ordered, though I've not personally seen any of the calculations or forecast results from this program. I believe that Zeiss supplied blanks only, the store's own lab did the glazing. I can only think (hope) that something has gone wrong (that far smaller blanks were used originally? That other thinning opportunities have been missed?) and therefore I will be able to get a satisfactory reglazing result, not too dissimilar from the 2013 pair, from another optician?
(I know higher index lenses exist, but I have suffered distortion from 1.74 in the past so am really focused on the change in this material for the moment.)
Two pairs of glasses from the same shop, one made in 2013 and the other brand new this week. Identical frames, apparently identical lenses (Zeiss 1.6 index), with what feels like a very small bump in prescription, has resulted in a dramatic change in lens thickness, to the extent that the optician was as surprised as I - but was ultimately unable to get a satisfactory answer out of Zeiss.
At the bottom of the photo you will see my original 2013 glasses - lens edge thickness is in the range of 2 - 2.2mm all around, in fact centre not much different either. Lenses fit the frames very well indeed.
2018 at the top - edge thickness has more than doubled, between 4.6 - 5mm and so presents very poorly in the same frame, more than double the lens weight, etc.
Prescriptions are as follows;
2013:
| SPH | CYL | AXIS | |
|---|---|---|---|
| Right | +4.25 | -2.00 | 96 |
| Left | +4.75 | -3.25 | 82 |
2018:
| SPH | CYL | AXIS | |
|---|---|---|---|
| Right | +4.50 | -2.25 | 95 |
| Left | +5.25 | -3.50 | 85 |
I'd be grateful for any insight! As far as I can see, my 2013 left lens is actually a higher power & cylinder than the new right lens, yet we still see a uniform >2x increase in thickness!
The store claim the same blank sizes were used (70mm). Apparently Zeiss 'Optima' was ordered, though I've not personally seen any of the calculations or forecast results from this program. I believe that Zeiss supplied blanks only, the store's own lab did the glazing. I can only think (hope) that something has gone wrong (that far smaller blanks were used originally? That other thinning opportunities have been missed?) and therefore I will be able to get a satisfactory reglazing result, not too dissimilar from the 2013 pair, from another optician?
(I know higher index lenses exist, but I have suffered distortion from 1.74 in the past so am really focused on the change in this material for the moment.)
Edited by simion_levi on Wednesday 23 May 21:37
I'm an optometrist rather than a dispensing optician and we tend to use Hoya and Nikon rather than Zeiss but
I don't think the change in the prescription is enough to change the apperance of the lenses.
Blank size is a significant factor with your prescription, with a lot of high quality lenses such as Zeiss you make a scan of the frame shape and they calculate the smallest lens diameter they can cut it out of whilst still being correctly centred infront of your eyes.Did they send your frame off to have the new lenses or order uncut lenses and then glaze them whilst you waited?
Second glazing job is poorer as edges not polished.
Most lens manufacturers will calculate edge thickness for a given prescription frame, without knowing how big your frame is (smaller frame, smaller blank size(uncut lens diameter) in a +ve prescription the thinner the lens is I would think 1.6 or 1.67 index would be enough.
Also if I would have reglazed your frame with "premium" lenses I'd have replaced the nose pads!
I don't think the change in the prescription is enough to change the apperance of the lenses.
Blank size is a significant factor with your prescription, with a lot of high quality lenses such as Zeiss you make a scan of the frame shape and they calculate the smallest lens diameter they can cut it out of whilst still being correctly centred infront of your eyes.Did they send your frame off to have the new lenses or order uncut lenses and then glaze them whilst you waited?
Second glazing job is poorer as edges not polished.
Most lens manufacturers will calculate edge thickness for a given prescription frame, without knowing how big your frame is (smaller frame, smaller blank size(uncut lens diameter) in a +ve prescription the thinner the lens is I would think 1.6 or 1.67 index would be enough.
Also if I would have reglazed your frame with "premium" lenses I'd have replaced the nose pads!
The answer above is much more qualified than mine!
However, is this not the difference between standard lenses and 'thinner' lenses, which you are usually charged a handsome premium for?
The difference in thickness looks similar to my glasses when I ordered one with expensive, ar etc. etc. thinner lenses and one pair with regular lenses, in the same frame and the lenses were considerably thicker in the regular lens option.
However, is this not the difference between standard lenses and 'thinner' lenses, which you are usually charged a handsome premium for?
The difference in thickness looks similar to my glasses when I ordered one with expensive, ar etc. etc. thinner lenses and one pair with regular lenses, in the same frame and the lenses were considerably thicker in the regular lens option.
This is all because the lenses were are red from the supplier, who in this case happens to be Zeiss,, without the supplier having sight of the frame.
The lenses should have been made with minimum edge thickness which is basically just sufficient to withstand being cut to the frame.
They have probably used stock lenses of a diameter which was larger than it needs to be. They way to produce thin +ve lenses is to surface the lens and not use standard uncuts.
It's a very simple concept but one which is hard to explain in words.
I could show you in 2 minutes if you were sitting in front of me.
However, surfacing a lens rather than picking from stock costs more.
Zeiss is a brand, that's all. It's just one everyone has heard of.
The lenses should have been made with minimum edge thickness which is basically just sufficient to withstand being cut to the frame.
They have probably used stock lenses of a diameter which was larger than it needs to be. They way to produce thin +ve lenses is to surface the lens and not use standard uncuts.
It's a very simple concept but one which is hard to explain in words.
I could show you in 2 minutes if you were sitting in front of me.
However, surfacing a lens rather than picking from stock costs more.
Zeiss is a brand, that's all. It's just one everyone has heard of.
Hard to explain in words. Yes.
Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
I had a run-in with the national brand that took over another nation brand and sounds like it might sell footwear. The new glasses inter-ocular distance was wrong such that I could get the subject in focus in one eye at a time only. I had to move my head from side to side. In any case, even individual lens vision was no better than the original prescription and for this they wanted c.£400. I politely asked them to poke them where the sun doesn't shine. Specsavers have always given good service and value for me so it's back there next time. They use Pentax lenses I believe.
FiF said:
Hard to explain in words. Yes.
Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
Christ that gets up my arse. All these smart-arse know-alls telling people on fora like this that they should get their Spex/white goods/cameras/ and so on online and bemoaning the fact that their high street is dying. Well, you can't have both.Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
Johnspex said:
FiF said:
Hard to explain in words. Yes.
Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
Christ that gets up my arse. All these smart-arse know-alls telling people on fora like this that they should get their Spex/white goods/cameras/ and so on online and bemoaning the fact that their high street is dying. Well, you can't have both.Meanwhile I'll just stick this here as a bit of light reading and a poke at the "buy specs online as all high street opticians are robbers" mob.
Understanding lens thickness
Though I used to giggle when the buyers got their arse burnt on the fine print, e.g. going for a cheaper headline price only to find that they had been comparing delivered their facilities duty paid, with a factory door price, packing extra, or FOB t'other side of the world duty unpaid. Oh how we laughed.
Some know price of everything, value of nothing. Don't miss it till it's gone.
HelenT said:
I'm an optometrist rather than a dispensing optician and we tend to use Hoya and Nikon rather than Zeiss but
I don't think the change in the prescription is enough to change the apperance of the lenses.
Blank size is a significant factor with your prescription, with a lot of high quality lenses such as Zeiss you make a scan of the frame shape and they calculate the smallest lens diameter they can cut it out of whilst still being correctly centred infront of your eyes.Did they send your frame off to have the new lenses or order uncut lenses and then glaze them whilst you waited?
Second glazing job is poorer as edges not polished.
Most lens manufacturers will calculate edge thickness for a given prescription frame, without knowing how big your frame is (smaller frame, smaller blank size(uncut lens diameter) in a +ve prescription the thinner the lens is I would think 1.6 or 1.67 index would be enough.
Also if I would have reglazed your frame with "premium" lenses I'd have replaced the nose pads!
Thanks to all for comments. I'm glad to hear that a much better result is not out of the question! I don't think the change in the prescription is enough to change the apperance of the lenses.
Blank size is a significant factor with your prescription, with a lot of high quality lenses such as Zeiss you make a scan of the frame shape and they calculate the smallest lens diameter they can cut it out of whilst still being correctly centred infront of your eyes.Did they send your frame off to have the new lenses or order uncut lenses and then glaze them whilst you waited?
Second glazing job is poorer as edges not polished.
Most lens manufacturers will calculate edge thickness for a given prescription frame, without knowing how big your frame is (smaller frame, smaller blank size(uncut lens diameter) in a +ve prescription the thinner the lens is I would think 1.6 or 1.67 index would be enough.
Also if I would have reglazed your frame with "premium" lenses I'd have replaced the nose pads!
My frame was sent away, but I believe the American-owned-warehouse-chain have their own lab (or else contract it out to another party) who actually do the cutting/fitting and Zeiss only supplied blanks to order. I am told that they ordered from Zeiss with their 'optima' program, which supposedly takes into account frame size/shape to produce the thinnest lens for a given index material, just as you say (see here for Zeiss literature). However, given the poor result, I'm inclined to believe that this has not really happened, or has somehow gone wrong!
I'll call round a few local Opticians and see what they can offer.
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