# Optical Forums > Progressive Lens Discussion Forum >  Are we getting carried away?

## scriptfiller

Digital lenses accurate to within 1/100th of a diopter...

I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...

Free-form this free-form that, thousands of free-form flavors...

I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's.  It seems that the industry is getting a little carried away.

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## Now I See

Someone (a rep) told me to think about music and how it has gone from records, to 8-tracks, to cassette tapes, then to CD's....still the same music, just a different delivery. ;)

**sigh** I wish I knew the answer to your question, the best advise I got when posing the same type of question was to remember that a progressive is still a progressive no matter how you cut it. :)

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## Robert Martellaro

> Digital lenses accurate to within 1/100th of a diopter...


Not important.




> I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...


The Physio is already enhanced for large pupils. If I feel it's necessary to try the new version I'll do so. If I can see a difference I'll let you know.




> Free-form this free-form that, thousands of free-form flavors...


Where's the meat! 



> I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's.


In some situations, yes. The lens I'm presently wearing uses this technology, and is giving me visual performance that has been unequaled by any other PAL design that I've tried. 

That said, I would concentrate on getting the most appropriate design in front of your clients's eyes as possible, free-form/pow optimized or not. For some, that wil mean getting the distance zone as wide and as free of aberrations as possible, and still has a short enough corridor that minimzes posturing for those with Adds over +2.00. Others may do better with a very soft design and a longer corridor.

Sounds like you need a guinea pig. 




> It seems that the industry is getting a little carried away.


There's a strong push for market share. There are many advantages to eliminating semi-finished PALs from the loop. Prices will decline. The future is now.

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## rbaker

> Digital lenses accurate to within 1/100th of a diopter...
> 
> I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...
> 
> Free-form this free-form that, thousands of free-form flavors...
> 
> I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's.  It seems that the industry is getting a little carried away.


It's the same as we used to do in the third grade school yard. My Wilie is bigger than your Willy! It's ad-speak to impress the uneducated. You have to try to distinguish your produce over all others even it it entails building a huge pile of horse pucky (as Col. Sherman T. Potter would say.)

There is an engineering concept called "appropriateness of scale" whch states that it is not necessary to increase the atomicity of a measurement system beyond the scale that is requires to complete the process. In plain English this is why carpenters do not use micrometers to frame a house.

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## finefocus

> It's the same as we used to do in the third grade school yard. My Wilie is bigger than your Willy! It's ad-speak to impress the uneducated. You have to try to distinguish your produce over all others even it it entails building a huge pile of horse pucky (as Col. Sherman T. Potter would say.)
> 
> There is an engineering concept called "appropriateness of scale" whch states that it is not necessary to increase the atomicity of a measurement system beyond the scale that is requires to complete the process. In plain English this is why carpenters do not use micrometers to frame a house.


(1) Also, the doctrine of significant figures - no point in generating an answer accurate to 5 decimal points if the data was accurate to 2 decimals. An Rx written in 8th diopter steps is pushing it; 100th diopter steps are beyond the pale.

(2) I noticed a big difference with freeform PAL's, but not in what I saw; it's what I didn't see. Less of the usual side effects of PAL's, peripheral blur, small sweet spots, swimmy lower outside corners, etc.

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## AWTECH

> Digital lenses accurate to within 1/100th of a diopter...
> 
> I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...
> 
> Free-form this free-form that, thousands of free-form flavors...
> 
> I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's. It seems that the industry is getting a little carried away.


Do you recommend AR?  Did you 10 years ago?  The trend is toward more AR and the US is far behind Europe in percentage of AR sales.  Even farther behind Japan.  

Now Freeform which is newer than AR comes along and the trend is the same Japan as a percentage of jobs is way ahead, Europe is not quite as high, but much higher than the US.   (All Freeform is not the same)

Less distortion is possible, Thinner lenses are possible, better overall performance.  If the price for traditional vs. freeform was the same there would be no question.

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## k12311997

> Do you recommend AR? Did you 10 years ago? The trend is toward more AR and the US is far behind Europe in percentage of AR sales. Even farther behind Japan. 
> 
> Now Freeform which is newer than AR comes along and the trend is the same Japan as a percentage of jobs is way ahead, Europe is not quite as high, but much higher than the US. (All Freeform is not the same)
> 
> Less distortion is possible, Thinner lenses are possible, better overall performance. If the price for traditional vs. freeform was the same there would be no question.


 
In Europe and Japan glasses are fashion in America they are a medical device:hammer:.  In Europe and Japan who needs free form for thinner lenses I've seen glasses from overseas with a .5 ct.

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## AWTECH

> In Europe and Japan glasses are fashion in America they are a medical device:hammer:. In Europe and Japan who needs free form for thinner lenses I've seen glasses from overseas with a .5 ct.


Everyone is entitled to their opinion but I personally don't think in the US they are a medical device only, no more than they are in Japan and Europe.

As for Thinner lenses just by being 0.5mm CT is not always a good solution such a thin lens can be too flexible.  In many cases especially with a PAL a good design freeform will be thinner.  In most cases the optical performance will be superior due to managing power error and off axis astigmatism.

I think the Freeform Train has Left the Station

Like I said, if the same scipt could be had in conventional PAL or good design freeform why would you use traditional?

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## k12311997

that remark was public percption, not my opinion.

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## AWTECH

> that remark was public percption, not my opinion.


If I understand what you are saying is that in America vs Europe and Japan we seem to be price is everything vs the ability to balance the true value.  I often find myself looking at those low price ads on a product I know little about, then I catch myself and say what is the value of the purchase to me at the price offered.

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## OCP

> Digital lenses accurate to within 1/100th of a diopter...
> 
> I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...
> 
> Free-form this free-form that, thousands of free-form flavors...
> 
> I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's. It seems that the industry is getting a little carried away.


There IS actually a noticeable difference from conventional pals and freeforms, but as most of you know here, I agree that the industry are going way to far with all these trivial measures. "Pupil diameter". Come on. I´m sure Essilor could tell us a long prevarications of why this is important, and some will eat this history with skin and hair, but this has gone to far in my opinion.

Mike.

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## Uilleann

I'm certainly interested to learn more about what this lens claims it may do for my patients.  And I'll happily put it to the test in the real world and see if there is an appreciable difference for my practice.  Technology is advancing, and ophthalmic optics are not immune to advances as well.  Ten years ago, I was quite content with my old 24" tube TV and VHS tape movies.  Now, the 52" LED/LCD 1080P display makes my Blu-ray copy of the BBC documentary Planet Earth look frighteningly realistic and sharp.  The difference is certainly a 'wow' type experience.

Will our humble little lenses ever deliver such an easily seen difference in the future?  Who knows.  But there is one certainly - the only guaranteed way to fail, is never to try.  Give the new tech a shot.  Educate yourself as much as you can - always ask lots of good questions (like this thread).  You will be wiser for the knowledge and experience of it all...and may very well have an exceptional lens offering available at the end of the day.

Best!!  :cheers::cheers::cheers:

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## lind2020

The U.S is behind foriegn countries in anti-reflective percentage because in the U.S. you have to pay for it.

Apples -vs- Apples please...


p.s. Perhaps obama's now defunct (or soon to be) plan may give U.S. residents free a/r also....

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## AWTECH

> The U.S is behind foriegn countries in anti-reflective percentage because in the U.S. you have to pay for it.
> 
> Apples -vs- Apples please...
> 
> 
> p.s. Perhaps obama's now defunct (or soon to be) plan may give U.S. residents free a/r also....


What countries do you not have to pay for it?  There is no manufacturer producing AR for free.  I know some countries have different government insurance plans and insurance is different from country to country but usage is still much higher in European countries where the patients pay than it is here.

The bigger difference has to do with the facilities that manufacture lenses.  In Japan for example the majority probably 90% are manufactured by about 6 different lens manufactures. They don't have independent labs or in office labs like we do here and in each of these factories they invested in AR equipment and pushed the products as a complete package.

Here in the US in house quick delivery was determined to be more important than sending a lens surfaced at an in office facility out for AR.

Another factor was the first AR usage in the US was a failure due to the UV hard coating used almost exclusively in the US that was not very compatible with AR, so the AR got blamed as bad when it was the hard coating that the AR would not bond to.

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## Pete Hanlin

Someone (a rep) told me to think about music and how it has gone from records, to 8-tracks, to cassette tapes, then to CD's....still the same music, just a different delivery.
I'm glad our consultants were paying attention to my presentation at our recent National Sales Meeting!  :)

The point was this:  The _content_ of the MUSIC is a lot more important than the format used to _deliver_ it.  When I hear practitioners say they only want to dispense "digitally surfaced designs" it just doesn't make any sense to me.  Its like walking into a music store and saying _"Hey, sell me some CDs!"_ without any regard for what's ON the CD!  I'd rather listen to _Billy Joel_ on a cassette tape than _New Kids on the Block_ on a CD.  I'd rather watch _Star Wars_ on a VHS than _Cabin Boy_ on DVD.  Sure, DVDs and CDs make good music a bit clearer (though some would argue records actually sound better), but it doesn't matter what format you play it on, the _New Kids_ will never match _Billy Joel_ (IMHO)...  Point is, traditionally surfaced PALs outperform digitally surfaced PALs when the design in the traditional lens is better (and there are independently conducted clinical studies which back this statement up).  

To the original point... I agree that moving from 0.06 to 0.01D accuracy is "negligible" in terms of measurable benefit to the wearer.  Just think about it- when does an examination end?  When the patient can't tell a difference between lens 8 and 9 (or 9 and 10, etc...).  Those lenses are usually 0.25D apart, and the wearer cannot tell a difference!  How is that wearer supposed to notice a difference between a lenses that are 0.05D apart?  Increased accuracy isn't a bad thing, of course- and perhaps we will be able to refract closer to the "ideal Rx," but in the end it comes down to a measurable benefit for the wearer.  Digital surfacing- by itself- does not make a PAL "better."  A good design makes a PAL better.

Which brings us to Varilux Physio Enhanced.  We have some very encouraging clinical data which demonstrates a significant preference for Varilux Physio Enhanced (vs. Varilux Physio), so I'm pretty optimistic your patients will be impressed with the lenses (which is the end goal of us all).

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## YrahG

> (and there are independently conducted clinical studies which back this statement up).........................................................  .........................................
> Which brings us to Varilux Physio Enhanced.  We have some very encouraging clinical data which demonstrates a significant preference for Varilux Physio Enhanced (vs. Varilux Physio), so I'm pretty optimistic your patients will be impressed with the lenses (which is the end goal of us all).


You mentioned independent clinical studies in the begining and in the end you are mentioning clinical studies again, are these Physio Enhanced studies independent as well?

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## Pete Hanlin

Are these Physio Enhanced studies independent as well? 
Yes, they are. In the interest of full disclosure, I'll try to describe what I mean by independent (and leave it up to the reader to decide if the term is accurate).

When we conduct a clinical study, we contract with Schools of Optometry and/or other organizations which test ophthalmic products. Essilor funds the study, and reviews the study protocols- but the organization conducting the clinical procures the lenses and conducts the study. 

When I say _"reviews the protocols,"_ I mean we ensure the testing is being conducted in a double-blind, randomized environment, with a population which is representative of the population as a whole (for most tests, sometimes we want to test a specific population- for example on polarization, we may want to specifically test pseudophakes). We have had outside organizations review our clinical testing protocols as well, which has resulted in further independent certification of the protocols.

"Double-blind" means neither the subject nor the examiner knows the identity of each product being tested (two pair of identical eyewear- the only difference is one has a small dot in the inside of the hinge... there is an assistant that knows which lens is which for recording purposes, but s/he does not interact with the subject). "Randomized" means the order in which the products is varied (further removing the possibility of the subject/examiner knowing which product is which, and also removing "order bias" from the subject). 

Once the study is conducted, the organization provides an analysis of the results to Essilor. In the vast majority of cases, we grant permission for the organization to publish articles or posters on their findings- in many cases, I create "posters" which summarize the results. In other cases, the study may have been comparing developmental products (in which case, the results are sent back to Essilor R&D, which conducts even more tests than we do as part of the lens design process).

Conducting a clinical study is an expensive endeavor. For example, to remove as many variables as possible, we have to make sure all of the lenses a.) are made of the same material, and b.) have the same or similar AR treatment. The only material most competitors have in common is 1.67, so we usually end up ordering 80 pair of 1.67 w/AR PALs for the subjects. Usually you shoot for 40 or so subjects- knowing you need at least 30 subjects to acheive statistically significant findings (p-value of <0.05), and some subjects will "drop out" (for one reason or another, they will either not show for the visits or have a condition which excludes them from participation- such as an eye condition). Then the subjects have to be examined, fit with identical frames, and scheduled for the evaluations. 

Anyway, when clinical tests are conducted between products in this environment, we are often able to acheive statistically significant results (i.e., one product is DEFINITELY favored over another- either globally or in certain aspects). Other times, we find there is very little difference in the performance of two products. 

If I'm less than overwhelmed with some of the FBS digital products on the market, its because I've had them tested against traditional designs and have found that DESIGN has a _much_ larger impact on product performance than the PROCESS used to make the lens. There are several FBS designs which do not perform as well as traditionally processed designs. Of course, I focus mostly on Varilux products- but I would suspect traditional Zeiss & Hoya lenses would also perform better than some of the "FBS designs" on the market today.

Main point to all this is as follows- the claimed "benefits" of FBS processing (keyhole effect, greater accuracy, and supposed reduction of peripheral distortion) do _not_ appear to make an impact on the actual vision of real human subjects (which is what it all comes down to). For example, during a comparison of an FBS design to Varilux Comfort, a majority of subjects found Varilux Comfort to be wider in every zone compared to the FBS design (not to a level of statistical significance, but by a clear majority).  I'm saying this- if you take a traditional design and move it to the back surface, you will not find a difference in the performance of the design in a clinically controlled environment.  For all the hype about "full-back surface" benefits, they just don't pan out in real life (which is what I suspect practitioners will discover as they dispense more and more of these lenses).

Sorry for the length, but my involvement in the testing process over the past few years has really shed a lot of light on what makes a PAL "tick." I know digital surfacing sounds really cool- but its just another way to make a lens. That's not to say digital surfacing can't be used to create certain design elements which have significant impact (example, when Varilux 360 products are compared to non-360 products, we can measure improvements in performance with the 360 products), but digital surfacing alone just doesn't seem to make much difference in how a PAL performs.

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## YrahG

> Are these Physio Enhanced studies independent as well? 
> Yes, they are. In the interest of full disclosure, I'll try to describe what I mean by independent (and leave it up to the reader to decide if the term is accurate).
> 
> When we conduct a clinical study, we contract with Schools of Optometry and/or other organizations which test ophthalmic products. Essilor funds the study, and reviews the study protocols- but the organization conducting the clinical procures the lenses and conducts the study. 
> 
> When I say _"reviews the protocols,"_ I mean we ensure the testing is being conducted in a double-blind, randomized environment, with a population which is representative of the population as a whole (for most tests, sometimes we want to test a specific population- for example on polarization, we may want to specifically test pseudophakes). We have had outside organizations review our clinical testing protocols as well, which has resulted in further independent certification of the protocols.
> 
> "Double-blind" means neither the subject nor the examiner knows the identity of each product being tested (two pair of identical eyewear- the only difference is one has a small dot in the inside of the hinge... there is an assistant that knows which lens is which for recording purposes, but s/he does not interact with the subject). "Randomized" means the order in which the products is varied (further removing the possibility of the subject/examiner knowing which product is which, and also removing "order bias" from the subject). 
> 
> ...


Interesting points, thank you for sheding some light on your companies studies, I am a bit wiser today.  

With the FBS I think you are both right and wrong here.  I don't even necessarily think you are wrong more so than leaving key information out.  FBS PALs as you point out are not in and of themselves better because they have been moved to the back surface.  By having the design surfaced (notice I did not say back, front, or both) the software has the ability to design it on the fly rather than just make assumptions about many of the variables.  The 3rd quarter I am hearing you will be releasing the Drx line of your companies designs, rather than unlock the potential of designing the PAL on the fly your company is going to surface the design on the back unchanged and is positioning it as a inferior product to the Enhanced.  I am uspet that your company has taken a stance to position great technology as a parlor trick to bash the competition.  I think until the Varilux line incorporates custom variable in the design of the lens (front, back, or both) it will always have a disadvantage to fully customized designs.  I would like to see the Drx take advantage of the ability to customize the design.

Also on a side note the few studies of your companies that I have seen include pateints that were previous PAL wearers, since Varilux has the market share when it comes to PALs how do you ensure that the patient doesn't go from an older Varlux design to a newer improved version which would be a more natural adaption then lets say switching PALs from one manufacturer to another?

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## Pete Hanlin

YrahG,
Thanks for the thoughtful responses/objections.  

By having the design surfaced (notice I did not say back, front, or both) the software has the ability to design it on the fly rather than just make assumptions about many of the variables.
Actually, this is a frequently misunderstood aspect of "FBS" digital surfacing.  Most FBS lenses are not "designed on the fly" as you suggest.  In most of the FBS lenses currently on the market, a design _file_ is selected from which the lens is generated.  Yes, the distance power is "added in" to the design file, but it is not "designed on the fly."  Rather, there is a collection of pre-determined files from which a design is selected (which is really not _that_ different from selecting a base curve and ADD in the form of a progressive blank).  Zeiss Individual is an example of a FBS lens that is "designed on the fly" to a degree.  Position of wear is taken into account, and you can measure the impact on design from lens to lens.  This cannot be said of some of the other lenses on the market claiming position of wear customization.

Of course, the claim is asphericity/atoricity is used to "eliminate peripheral distortion."  Unfortunately, a.) not all FBS lenses truly feature atoricity to reduce marginal astigmatism & power error, and b.) even if you do incorporate this rather easily calculated feature, its not going to impact "peripheral distortion" to a great degree (reducing marginal astigmatism isn't a bad thing, but it doesn't necessarily reduce distortion).  

The 3rd quarter I am hearing you will be releasing the Drx line of your companies designs, rather than unlock the potential of designing the PAL on the fly your company is going to surface the design on the back unchanged and is positioning it as a inferior product to the Enhanced. I am uspet that your company has taken a stance to position great technology as a parlor trick to bash the competition.
Essilor's message on digital surfacing has remained rather constant- it adds nothing to the design on its own.  As such, we do not plan to follow the path of some other manufacturers when it comes to making exaggerated claims on the performance of an FBS formatted product.  The "parlor trick" is found in the claims of some FBS manufacturers who claim 20-30% (and more) gains in "width" when the design is moved the back.  The "parlor trick" is leading practitioners and consumers to believe they will have "6x increased resolution" with digitally surfaced lenses (based solely on the theoretical 0.01D accuracy of DS vs. the 0.06D accuracy of traditional generating).  The "parlor trick" is claiming that a lens is "designed on the fly" just because the surface is stored in a computer instead of on a mold.

Varilux offers several design features which are applied using digital surfacing.  We have had 360 Optimized products on the market for some time, and we are launching Varilux Physio Enhanced next week which will feature customized wavefront correction.  These products have been tested and we know they provide real benefits over the traditionally surfaced versions of the designs.  Digital surfacing is a great thing- but (to the original point of this thread) the market has certainly gotten "carried away" with the supposed "benefits" of digital surfacing in and of itself.

Also on a side note the few studies of your companies that I have seen include pateints that were previous PAL wearers, since Varilux has the market share when it comes to PALs how do you ensure that the patient doesn't go from an older Varlux design to a newer improved version which would be a more natural adaption then lets say switching PALs from one manufacturer to another? 
Excellent question- and a valid point.  Which is why part of the initial subject interview process is to ascertain what design they are currently wearing.  In many studies, we specifically ensure the subjects are not currently wearing either of the designs being tested.  In some studies, there is a "washout" pair (which is a "control" design which is neither of the lenses being evaluated) which is worn for a period of time prior to the subject's visit.

Long story short, in my experience FBS lenses do not outperform traditionally generated designs on actual humans.  I can understand why that upsets some people, but it just happens to be a statement of fact.  If you want to believe DS lenses are "designed on the fly," feel free to believe that- but it doesn't appear to improve the performance of the lens on people- which I'm guessing is the main objective in the end.

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## Now I See

Pete~

I'll give you an example of a recent exchange I had with a patient...

The pt was wearing Comfort CR39 w/o ARC.  I put him in a "digital" lens, CR39 w/ ARC (not a 360), pt had many complaints, so I switched him to a "better" design (still not a 360), pt had complaints, just not as many as the first time.  Frustrated with the whole experience, I remade them again...back to his original comfort CR39 w/ ARC. He hasn't picked these up yet, but I wonder if, I would have had so much trouble if I had put him in the Comfort 360, since he was already "used to" the Comfort design??

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## Pete Hanlin

Hello Heather,
As with all troubleshoots, there are so many factors involved it is hard to say why a patient fails to adapt to a particular lens. Most PAL designs (traditional and digitally surfaced) are pretty good. That said, there are one or two FBS PAL designs in particular where I can imagine a Varilux Comfort wearer might notice a significant difference in various areas of performance! On the other hand, perhaps the FBS design was okay, but the processing wasn't quite right (its harder to verify conformity of each lens in a DS process vs. a traditional surfacing process, but that's another discussion). I'm not trying to toss either the design or the process "under the bus," I'm just saying there's a lot of potential causes.  Then there's the patient him/herself!  Who hasn't fit a patient with the same design, same Rx, same fitting parameters... only to hear _"It just doesn't seem quite the same!"_

Regarding Varliux Comfort 360, if the patient was already in Varilux Comfort, Varilux Comfort 360 should be an easy fit- because it is an optimized version of Varilux Comfort.

The 360 Optimization calculates an irregularly atoric back surface which is applied using digital surfacing. "Irregularly atoric" means it uses atoricity to match the distance Rx to the progression on a point-by-point basis. Hypothetically speaking- on a given lens the program knows that at point _x=-3.1mm y=2.3mm_ from the PRP, the front progressive surface produces a power of +0.04 -0.18 x 002. Let's say the prescribed distance power is -1.25 -0.50 x 090. The calculation considers the power existing on the front and creates a curvature at the corresponding point on the back surface which will produce the prescribed distance power _without altering the design of the progression_ (the design of a PAL is altered by distance power in traditional and FBS PALs).

Best regards,
Pete

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## YrahG

> YrahG,
> Thanks for the thoughtful responses/objections.  
> 
> By having the design surfaced (notice I did not say back, front, or both) the software has the ability to design it on the fly rather than just make assumptions about many of the variables.
> Actually, this is a frequently misunderstood aspect of "FBS" digital surfacing.  Most FBS lenses are not "designed on the fly" as you suggest.  In most of the FBS lenses currently on the market, a design _file_ is selected from which the lens is generated.  Yes, the distance power is "added in" to the design file, but it is not "designed on the fly."  Rather, there is a collection of pre-determined files from which a design is selected (which is really not _that_ different from selecting a base curve and ADD in the form of a progressive blank).  Zeiss Individual is an example of a FBS lens that is "designed on the fly" to a degree.  Position of wear is taken into account, and you can measure the impact on design from lens to lens.  This cannot be said of some of the other lenses on the market claiming position of wear customization.
> 
> Of course, the claim is asphericity/atoricity is used to "eliminate peripheral distortion."  Unfortunately, a.) not all FBS lenses truly feature atoricity to reduce marginal astigmatism & power error, and b.) even if you do incorporate this rather easily calculated feature, its not going to impact "peripheral distortion" to a great degree (reducing marginal astigmatism isn't a bad thing, but it doesn't necessarily reduce distortion).  
> 
> The 3rd quarter I am hearing you will be releasing the Drx line of your companies designs, rather than unlock the potential of designing the PAL on the fly your company is going to surface the design on the back unchanged and is positioning it as a inferior product to the Enhanced. I am uspet that your company has taken a stance to position great technology as a parlor trick to bash the competition.
> ...


I hope this doesn't come off as rude since I enjoy your posts but your post seemed quite canned.  I did not suggest that most FBS lenses are designed "on the fly", in contrast I said:




> By having the design surfaced (notice I did not say back, front, or both) the software has the ability to design it on the fly rather than just make assumptions about many of the variables.


So the entire first two paragraphs are great information but don't address the question of why Essilor's newest offerings this year choose not to take advantage of the newest technology?

You mentioned "custom wavefront correction", The design is on the front and incorporates nothing more than the prescription, seg hgt, and PD supplied so custom wouldn't be my first choice in descriptive terms.  Second you mention wavefront, yet I have not seen any way to incorporate wavefront aberrometry into your lens design so that term again is a bit misleading.  

The information I have recieved seems to put a lot of emphasis on pupil size, stop size, or aperature depending on who you ask.  This leads me to believe that the correction emphasis is on spherical aberration.  When you mentioned above in your post:

power errormarginal astigmatismdistortionspherical aberrationcoma
Of the seidel aberrations I would rank them in the order above as to their importance.  The pupil size is small enough that spherical aberration and coma are negligable similar to your example on the benefits from the potential accuracy gain from 0.o6D rounding to 0.01D rounding (again notice I said potential).

Your above posts seems to provide just as much claims as you seems to believe your competitors claim.  Also the 30% wider field claim I heard was in reference to the physio enhanced, physio 360, and many of the other Varilux products when they were first introduced.  To this day I don't have a base line measure of what "30% wider than" really means.  Are we talking about 30% wider than a peanut or a golf ball?  I have heard it is a reference to the first generation PAL designs in which case many manufacturers can make similar claims.

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## Pete Hanlin

I hope this doesn't come off as rude since I enjoy your posts but your post seemed quite canned.
I don't think you're being rude at all.

 I did not suggest that most FBS lenses are designed "on the fly?"
Okay, so which lenses do you feel are "designed on the fly" (because there are not many)?  I can think of a few examples: Varilux Ipseo IV, Varilux 360 products, Varilux Physio Enhanced, Zeiss Individual.  Most of the other products on the market are calculated using the process I described earlier (i.e., there is a catalog of pre-determined designs, and the computer selects the best file).

So the entire first two paragraphs are great information but don't address the question of why Essilor's newest offerings this year choose not to take advantage of the newest technology?
I'm afraid I do not follow your question.  The newest offering this year is Varilux Physio Enhanced, which is digitally surfaced on the back- with a molded front surface.  I'm just not sure what "newest technology" isn't being taken advantage of...

Your above posts seems to provide just as much claims as you seems to believe your competitors claim. Also the 30% wider field claim I heard was in reference to the physio enhanced, physio 360, and many of the other Varilux products when they were first introduced.
Obviously, I disagree.  Competitors are claiming to provide a 30% gain in width due to the geometrical advantage of having the design on the back surface (and simple geometry demonstrates the actual advantage is around 6%).  The 30% claim on Varilux Physio is related to the design (specific comparison is to Varilux Panamic) and has been demonstrated on actual wearers.  Specifically, the vertical alignment of cylinder in the near intermediate periphery provides a greater width of binocularity- which results in the perception of a wider intermediate field of view.

Regarding your skepticism re: wavefront correction, all I can say is the lenses have been measured for MTF (modulation transfer function), which is objectively higher than competitive lenses.  Additionally, we have studies which show the preference for Varilux Physio Enhanced increases in lower light conditions (which is exactly what one would expect if higher order aberrations are being controlled) compared to Varilux Physio.  Finally, we are measuring contrast perception on actual humans wearing the lenses.

I completely agree with a skeptical attitude towards new products (especially given the "fuzzy" nature of most ophthalmic marketing).  On the other hand, considering one of my main duties at Essilor is product testing, you should be able to understand that I get a little frustrated at some of the unsubstantiated (and sometimes demonstrably erroneous) claims out there when we spend so much time, effort, and resources towards proving the performance of our products.  I can demonstrate the benefits of our products on real wearers- I do not believe the claims of most digitally surfaced lenses can be substantiated in the same way.

Best regards,
Pete

----------


## YrahG

> I did not suggest that most FBS lenses are designed "on the fly?"
> Okay, so which lenses do you feel are "designed on the fly" (because there are not many)? I can think of a few examples: Varilux Ipseo IV, Varilux 360 products, Varilux Physio Enhanced, Zeiss Individual. Most of the other products on the market are calculated using the process I described earlier (i.e., there is a catalog of pre-determined designs, and the computer selects the best file).


If you can honestly say that the Physio products are designed on the fly, both the 360 and the enhanced then our dialog is done there is no where else to go.  Good luck with your product launch.

----------


## Pete Hanlin

Okay, well then- it was nice talking with you!

For the record, both Varilux 360 products and Varilux Physio Enhanced are, in fact, "designed on the fly" (to use your expression).  In fact, the calculations for these lenses are done remotely (the laboratory uses a high speed connection to download the tool path for each lens- the calculation cannot be done on a desk top computer).  This set-up is not unique to Essilor (my understanding is Zeiss Individual requires a remote connection as well).  There are no pre-set files for the back surface design- each lens surface is individually calculated.

BTW, I notice you didn't answer my question (i.e., what lenses do you think are "designed on the fly").

For anyone else that has been following this thread...  Just because a lens is digitally surfaced from a blank having a progressive front surface doesn't mean it can't be "designed on the fly."  I think we all agree a single spherical blank can be used to make all sorts of different progressive designs (this is the premise behind the FBS format).   The design elements you place on the back surface change the lens into any number of different designs.

Well, you can do the same thing with a blank having a progression on the front surface.  Depending upon the design you place on the back, you can shorten the progression, change the zones, or change the entire progression.  In fact, theoretically you could place a design on the back surface which changes the lens back into a single vision lens if you made the right calculations.  

One of the great myths of digital surfacing is that somehow having a spherical front surface is the best format for a progressive lens.  This is untrue for a number of reasons.  For example, in a traditional format (progression on the front), ADD power is created by increasing the base curve.  A traditional progressive lens with +3.00 ADD will _increase_ in curvature by approximately 3 diopters on the front surface.  Conversely, a progression with +3.00 ADD placed on the back surface will have a back surface that _decreases_ in curvature by approximately 3 diopters.  Professor Mo Jalie has an interesting paper which discusses this subject towards the end at the following link: http://www.ukoptometry.co.uk/wp-cont...-07revised.pdf

Again, digital surfacing is a cool technology which opens great new possibilities in progressive design.  The best selling digitally surfaced PALs in the world are made by Essilor (over two million pairs of DEFINITY lenses have already been sold in the US alone), so I have nothing against the technology.  I'm just hoping in 2010 we can start looking at this technology realistically (I'm a little tired of reading articles devoted to _"How to sell digitally surfaced lenses"_).  

Above all, we need to stay focused on how all these PALs are being FIT.  Getting the fit wrong by 1mm or so is going to impact the performance of the design a heck of a lot more than whether the lens is digitally surfaced or not.

----------


## scriptfiller

Pete, thanks for your replies.  They have been very informative.

I had a fellow optiboarder in the office today who demonstrated some  free-form PAL's.  It was very interesting and eye-opening.

----------


## YrahG

> Okay, well then- it was nice talking with you!
> 
> For the record, both Varilux 360 products and Varilux Physio Enhanced are, in fact, "designed on the fly" (to use your expression).


That is in fact a lie the design is on the front surface molded.




> In fact, the calculations for these lenses are done remotely (the laboratory uses a high speed connection to download the tool path for each lens- the calculation cannot be done on a desk top computer).  This set-up is not unique to Essilor (my understanding is Zeiss Individual requires a remote connection as well).  There are no pre-set files for the back surface design- each lens surface is individually calculated.


This set up is discussed in the Vision councils data communications standard from years back, this does not necessarily make the technology better in any way or say it is "designed on the fly".  This way to communicate could be used to provide a round seg if one choses or an older generation design.  I think for the most part this is way to obfiscate the facts your company is trying to avoid.  Also as a side note to change the front surface desing by using the back surface optics is just fixing a mistake that should never have been molded.




> BTW, I notice you didn't answer my question (i.e., what lenses do you think are "designed on the fly").


Fair enough, Zeiss Individual so far I have had the Shamir rep tell me the Auto II is "designed on the fly" I have not confirmed that yet so don't know it as a fact.




> For anyone else that has been following this thread...  Just because a lens is digitally surfaced from a blank having a progressive front surface doesn't mean it can't be "designed on the fly."  I think we all agree a single spherical blank can be used to make all sorts of different progressive designs (this is the premise behind the FBS format).   The design elements you place on the back surface change the lens into any number of different designs.
> 
> Well, you can do the same thing with a blank having a progression on the front surface.  Depending upon the design you place on the back, you can shorten the progression, change the zones, or change the entire progression.  In fact, theoretically you could place a design on the back surface which changes the lens back into a single vision lens if you made the right calculations.


I find this statement interesting as your right theoretically you could change the design based on what is surfaced on the back surface, yet none of the patents pertaining to the Physio 360 or the enhanced mention such technology.  Matter of fact although it is theoretically possible it doesn't make it feasable.  The reality of the situation is that to use two surfaces to accompish what you suggest means you are beating around the bush.

Physio Enhanced Patents:
7207675
7207674
7413303
6909498
7427134
7210780
7229173
7223164




> One of the great myths of digital surfacing is that somehow having a spherical front surface is the best format for a progressive lens.  This is untrue for a number of reasons.  For example, in a traditional format (progression on the front), ADD power is created by increasing the base curve.  A traditional progressive lens with +3.00 ADD will _increase_ in curvature by approximately 3 diopters on the front surface.  Conversely, a progression with +3.00 ADD placed on the back surface will have a back surface that _decreases_ in curvature by approximately 3 diopters.  Professor Mo Jalie has an interesting paper which discusses this subject towards the end at the following link: http://www.ukoptometry.co.uk/wp-cont...-07revised.pdf
> 
> Again, digital surfacing is a cool technology which opens great new possibilities in progressive design.  The best selling digitally surfaced PALs in the world are made by Essilor (over two million pairs of DEFINITY lenses have already been sold in the US alone), so I have nothing against the technology.  I'm just hoping in 2010 we can start looking at this technology realistically (I'm a little tired of reading articles devoted to _"How to sell digitally surfaced lenses"_).


Great article here is a point also discussed:

_"As the eye rotates behind
the empty aperture, the extent of field
which can be seen through the aperture
represents the apparent field of view. The
apparent field is influenced by the position
and size of the lens aperture, the larger the
aperture and the closer the aperture lies to
the eye, the larger the apparent field will be."

_The keyhole effect that many manufactureres of FF lens designs talk about has a connection here if we consider the width of the design as the aperature then by bringing it to the back the apparent filed of view is widened, this means that even your companies design could benefit from a back surface design if they could come to grips with the fact that they would have to admit to the back surface being beneficial.

_"However, the
relatively small increase in field offered by
a back surface progressive hardly warrants
such claims as “----- achieves wider fields of
view by creating the progressive design on
the back surface of the lens, rather than the
front.”

_I enjoy Professor Jalies work I own all of his books and read all the aticles, I thoroughly enjoyed this one thank you for pointing it out,  agree with both him and you that bringing the design to the back doesn't provide a huge increase in field of view but he does mention that it does provide an increase as well as you did in previous posts I believe 6% is what you said.  If you can admit that two surfaces can be used to accomplish what one surface can then you should also logically be able to admit that if the field of view can be widened by applying the progression to the back even your companies design which has the progression on the front and the prescription on the back could benefit an additional 6% if you were to switch the prescription to the front and progression to the back.

As an aside you may enjoy a previous post of mine on the differences between apparent field of view and real field of view:

http://www.optiboard.com/forums/show...56&postcount=2

Although it doesn't discuss width of a progressive it does discuss the corridor length for a myope compared to a hyperope.






> Above all, we need to stay focused on how all these PALs are being FIT.  Getting the fit wrong by 1mm or so is going to impact the performance of the design a heck of a lot more than whether the lens is digitally surfaced or not.


I have said before I can fit teh crapiest design properly and get better reulst compared to an office than fits the best design crappy.  Please try and discuss ONLY facts.  Lets's not read between any lines when we discuss.

----------


## thep

Yes!!:d

----------


## YrahG

Also consider the ISO tolerance on SV and PAL surfaces (ISO 10322-1&2)

SV
plano to 2.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.04
2.00 to 10.00 = Surface Power Error +/- 0.06; Surface Astigmatism 0.04
10.00 to 15.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.04

PALs
plano to 10.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.09
10.00 to 15.00 = Surface Power Error +/- 0.12; Surface Astigmatism 0.12

It becomes evident that the SV surface is held to tighter tolerances therefore would provide a more accurate base to work from.  That means in low astigmatic powers the axis can be supplied more accurately.  I don't think that this alone is significant enough to be a benefit in and of itself but you add up all the small benefits and you start to see a gain in accuracy.

Assume the worst case scenario in both the SV and PAL lets say a power of 15.00 the difference is going to be +/-0.04 n power and 0.08 astigmatism combine that with the worst case scenario on a traditionally tooled lens 0.04D that's +/-0.08 power with a 0.08 astigmatism.  We're getting near that line in the sand where the error becomes significant.

----------


## AWTECH

> Also consider the ISO tolerance on SV and PAL surfaces (ISO 10322-1&2)
> 
> SV
> plano to 2.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.04
> 2.00 to 10.00 = Surface Power Error +/- 0.06; Surface Astigmatism 0.04
> 10.00 to 15.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.04
> 
> PALs
> plano to 10.00 = Surface Power Error +/- 0.09; Surface Astigmatism 0.09
> ...


Standards have nothing to do with actual tolerances.  A manufactures actual curves produced are controlled by their own manufacturing standards.  ANSI is a minimum standard not an absolute manufacturing fact for all manufacturers.

----------


## YrahG

> Standards have nothing to do with actual tolerances.  A manufactures actual curves produced are controlled by their own manufacturing standards.  ANSI is a minimum standard not an absolute manufacturing fact for all manufacturers.


I was referencing the ISO standards for front curvature, ANSI is a whole subject in and of itself.  Given the potential accuracy of FF lenses it may be worth revisting tolerances and maybe even creating a seperate class of tolerances for FF lenses but that's going off tangent.  My posts was just to illustarte that a SV blank has the potential to be more accurate.  In every case discussed here we are talking about the potential to realize greater accuracy.  Actually provideing that accuracy is another story.

----------


## AWTECH

> I was referencing the ISO standards for front curvature, ANSI is a whole subject in and of itself. Given the potential accuracy of FF lenses it may be worth revisting tolerances and maybe even creating a seperate class of tolerances for FF lenses but that's going off tangent. My posts was just to illustarte that a SV blank has the potential to be more accurate. In every case discussed here we are talking about the potential to realize greater accuracy. Actually provideing that accuracy is another story.


I am not sure if I got my point across.  ISO and ANSI are both minimum suggested standards.  As an example if your tires on  your car are recommended to be kept at a pressure between 28 and 32 pounds but in a fleet they are checked daily and maintained at 29 to 30 pounds by this fleet management policies, is just going to produce reduced tire wear.  Another person is still within standards if they drive at 28 pounds.

The standards are a broader range that some companies may adopt.

----------


## YrahG

> I am not sure if I got my point across.  ISO and ANSI are both minimum suggested standards.  As an example if your tires on  your car are recommended to be kept at a pressure between 28 and 32 pounds but in a fleet they are checked daily and maintained at 29 to 30 pounds by this fleet management policies, is just going to produce reduced tire wear.  Another person is still within standards if they drive at 28 pounds.
> 
> The standards are a broader range that some companies may adopt.


Understood, however any company that I have dealt with that has tighter standards than industry norms has made a point of letting me know.  Even in the molding method digital production of moulds has lead to greater accuracy so I would highly doubt that anyone is sitting on the razors edge of any standard.

The mention of ISO standards here was to illustrate the reason why I feel a SV blank could be considered a better option to start a FF design, let's not get off on a tangent.

I believe that the simplicity of the surface also lends to greater efforts put into the design rather than to counter the design like in the previously mentioned posts.  This could mean more time spent on improving the design rather than getting it to come out right.  Lot's of fun and interesting stuff with FF lenses.  Simply put our knowledge of optics has not changed with this new technology, same $hit different day as they say.  Sure FF offers the potential for greater design flexibility but the software vendor has to choose to use this flexibility for anyone to see the benefits.  So far I have heard alot about the technology and little about the design goals, this was similar to moulded progressives.

----------


## Pete Hanlin

That is in fact a lie the design is on the front surface molded.
Ah, so I'm glad to see our discussion is not over! :)
Yes, the front surfaces of all the Varilux 360 PALs are molded. So are the front surfaces of FBS PALs! The difference is the front surface of an FBS PAL is spherical, and the front surface of a 360 PAL has progression on the front.

Either way (whether you start with a spherical front surface or a progressive front surface), you can create any design you want using the back surface. I've tried to explain this repeatedly in this thread.

The reality of the situation is that to use two surfaces to accompish what you suggest means you are beating around the bush.
On this point you are entirely mistaken. I'm not trying to be rude, but you seem resolute in stating Essilor does not use the back surface to modify a progressive front surface. In fact, I can cite several specific examples where Essilor uses two surfaces to acheive the final progressive design (generally speaking, we call this DDV- Dual Digital Vision... the front surface has a progression which has been molded and the back surface is used to modify that design and in some cases change it altogether).
I'll try to give a few examples, but the main point is what I've repeatedly said- just because you have progression on the front of a lens doesn't mean you can't modify the design "on the fly" to any parameter of your choosing. Actually, this is mentioned in a Zeiss white paper on Zeiss Individual (Zeiss indicates they prefer a FBS format because it is difficult to align the two surfaces precisely... Essilor has spent considerable resources on equipment dedicated to aligning the sides).

*DEFINITY*- First, DEFINITY is- by definition- a progressive design which is created by molding part of the progressive effect on the front and part on the back. Furthermore, both DEFINITY and DEFINITY SHORT are made from the _same exact molded blank_ (yet they are definitely different progressive designs). The design can be made shorter or longer by digitally surfacing design elements onto the back surface (changing progression length is one of the "customized" features touted by FBS designs, as I recall). Additionally, the inset of the progression is changed in DEFINITY by changing the back surface design (the inset on the front surface is locked- because it is molded- it is modified by the back surface).
*Accolade Freedom*- Also has a progression molded on the front- but the progression length changes based on fitting height (through digitally surfaced customization of the back surface) AND we change the distribution of zones based on frame shape (again through the back surface).
*Varilux Ipseo IV-* The previous generation of Varilux Ipseo (which is personalized to the Head/Eye Movement Ratio) was actually FBS. However, we found we could do MORE customization of the design by placing part of the progression on the front of the lens and digitally surfacing progression on the back as well. How does that work? Depending on the H/E Ratio, a person with a +2.00 ADD can have as much as +4.00 ADD on the front or as little as +0.75 ADD on the front. The back surface will have anywhere from +1.25 - -2.00 of ADD power/digression. Additionally, the progression length changes based on fitting height (which is all accomplished on the back surface), and the zones are redistributed based on the frame shape (by modifying the back surface). Coincidentally, the progressive blank used to create Varilux Ipseo can also be turned into any of the Varilux designs (with the right back surface).
*Varilux 360-* The patent which covers the 360 calculation (which was discussed at the launch of Varilux Physio in 2006) describes a unique calculation which is applied to the back surface of the lens and which is based upon the design characteristics of the front surface.

Fair enough, Zeiss Individual so far I have had the Shamir rep tell me the Auto II is "designed on the fly" I have not confirmed that yet so don't know it as a fact.
I've repeatedly indicated that Zeiss Individual is designed on the fly- so no problem there. Regarding Autograph, I encourage you to carefully read their description of "Direct Lens Technology" at their website (link: http://www.shamirlens.com/ecp/patented-technology.aspx).

I truly hope we can continue to keep the tone of the conversation friendly, as I've received several PMs from people who are following our posts and find them informative. I know its hard to change a position once it is stated, but I think the main point of contention is the belief that having a molded frontside progression means you cannot truly customize the lens. In reality you can, and Essilor has numerous products on the market which do just this.

Best regards,
Pete

----------


## Mr. Finney

Pete, if you can take any of these molded blanks and create any pal design via backside digital surfacing, why have so many branded options?  Just to create more market share?  It sounds like you really only have two "freeform" blanks: Definity and the others, since they could all become each other with surfacing tweaks. :Confused:  :Confused:

----------


## Fezz

> That is in fact a lie the design is on the front surface molded.
> Ah, so I'm glad to see our discussion is not over! :)
> Yes, the front surfaces of all the Varilux 360 PALs are molded.  So are the front surfaces of FBS PALs!  The difference is the front surface of an FBS PAL is spherical, and the front surface of a 360 PAL has progression on the front.
> 
> Either way (whether you start with a spherical front surface or a progressive front surface), you can create any design you want using the back surface.  I've tried to explain this repeatedly in this thread.
> 
> Pete



Pete,

I was checking cylinder power availability for the Comfort and the Comfort 360 in the Frames Lens Guide. I see that the Comfort list cyl. power up to 4.00. The Comfort 360 lists cyl. power up to 6.00. I forget what material (1.67?). I don't have the guide at home to double check.

What I am having a hard time grasping is:

If the blank being used is the same, how can the 360 offer an extra 2.00 in cylinder power?

Thanks!

:cheers::cheers::cheers::cheers:

----------


## Uilleann

What a great thread!  I feel like I'm bathing in knowledge....it feels kinda squidgee.....I likey!   :Cool: :cheers::cheers::cheers:

----------


## Mr. Finney

> What a great thread!  I feel like I'm bathing in knowledge....it feels kinda squidgee.....I likey!  :cheers::cheers::cheers:


Okay, no I'm getting a little concerned  :Rolleyes:

----------


## OCP

> Pete,
> 
> I was checking cylinder power availability for the Comfort and the Comfort 360 in the Frames Lens Guide. I see that the Comfort list cyl. power up to 4.00. The Comfort 360 lists cyl. power up to 6.00. I forget what material (1.67?). I don't have the guide at home to double check.
> 
> What I am having a hard time grasping is:
> 
> If the blank being used is the same, how can the 360 offer an extra 2.00 in cylinder power?
> 
> Thanks!
> ...


Comfort is a conventional product made with a progressive blank.
Comfort 360 is made in a Freeform generator, and use plano blank.
Software accept up to 6 cylinder.

Mike

----------


## Mr. Finney

> Comfort is a conventional product made with a blank.
> Comfort 360 is made in a Freeform generator, and use no blank.
> Software accept up to 6 cylinder.
> 
> Mike


WHOA!!  How do they do that?  Like, they produce a lens from black matter or something, just plug in the Rx info and "SHAZAM!", there it is?

 :Rolleyes:  :Rolleyes:  :Rolleyes:  :Confused:  :Confused:  :Confused: :bbg::bbg::bbg::cheers:

----------


## Fezz

> Comfort 360 is made in a Freeform generator, and use no blank.
> 
> Mike


WOW!

They really are "Invisible bifocals"!!!!

----------


## Pete Hanlin

Pete, if you can take any of these molded blanks and create any pal design via backside digital surfacing, why have so many branded options? Just to create more market share? 
Each PAL design has its own technologies and purposes, and yes- market niches to fill.  
On the Varilux side, the portfolio has two platforms- Varliux Comfort (which provides natural vision) and Varilux Physio (which adds WAVE Technology).  Of course, you need short versions of each design (plus versions that feature customization to Rx, frame shape, and/or the position of wear).  Varilux Ipseo IV is an exclusive-offering product, and Varilux Sport is a specialty niche (the Sport format is FBS, btw). 
DEFINITY has its own design technology and market position as well (simpler portfolio- regular and short), and Accolade and the rest of the Essilor PALs are designed for the retail market- or for private practitioners.  Generally, although there are a lot of products, there are specific customers who want each of those products (or we wouldn't make them).  In fact, discontinuing a product is difficult, because inevitably there are practitioners who "love" that particular product and don't want to see it go away.

It sounds like you really only have two "freeform" blanks: Definity and the others, since they could all become each other with surfacing tweaks.
Regarding the number of blanks used to create DS lenses at Essilor, off the top of my head there are at least six different progressive blanks (Varilux Physio, Varilux Comfort, Varilux Ellipse, DEFINITY, Accolade, DEFINITY, and the blank used to create Varilux Ipseo IV).  We also use spherical blanks to create Essilor Ideal products.

Although numerous designs _can_ be made from a single progressive blank, the objective is to do only what is necessary to customize the design on the back surface.  After all, there's no point in "recreating the wheel."  If a molded surface can be used to create certain design components, its actually good to go ahead and use the molded surface.  

Molds are great for their reproducability/consistency, which is why they are used to create the components of a design which remain consistent from lens to lens (even the most customized of designs have SOME components which remain consistent- e.g., most progressives increase in plus power in the lower portion of the lens).  Digital surfacing is great for customizing/modifying the design, but digital surfacing is inherently challenging from a consitency standpoint- so it makes sense to limit its use to design components that require customization.

Why is digital surfacing "challenging" from a consistency standpoint?  Well, the advantage of digital surfacing (the ability to unlock points on a surface) is also the biggest challenge of digital surfacing, because the points also have a tendancy to move around on their own if the process isn't tightly controlled!

In a traditional process, the entire progressive design is molded onto the front of the lens.  If the surfacing process gets out of control, the distance power may be off a bit, but the design itself is _usually_ not compromised (since its molded on the front of the lens, and the lab is generating the back surface).  When you place the entire design on the back of the lens via digital surfacing; however, if the process isn't under control the design _is_ compromised (because its being created by the process, instead of by a mold).  

Digital surfacing is challenging to control because a.) variables in the process have a greater impact on the final product quality, and b.) it's harder to measure the accuracy of the final product.  Several manufacturers are trying to develop equipment which can be used in the lab to measure the conformity of digitally surfaced lenses, but today most labs run test lenses in the morning and then trust the process is under control for the rest of the shift/day.  Most of the major lens manufacturers have invested tons of money to ensure process control of their digital surfacing processes (which is why you see manufacturers creating big central DS labs where they can oversee the process).  That's not to say local independent laboratories can't produce great digitally surfaced products, but it certainly helps if a manufacturer can provide process support (I know Zeiss and Essilor have certification processes for labs which digitally surface their lenses, I do not know what level of support is offered by Seiko, Kodak, and Shamir).

All this to explain why Essilor has- to date- adopted the DDV model for digitally surfaced lenses (molded progression on the front with additional customizing design components on the back surface).  With DDV, the "base design" is locked into the front (via the mold), and the customization is done with the back surface (via digital surfacing).  That way, you absolutely ensure the conformity of the base design while also having the ability to customize the design as much as you like.  In other words, we use molds for their consistency and combine them with digital surfacing which provides almost unlimited customization possibilities.  The result- hopefully- is customized products with a high consistency of quality from lens to lens.

----------


## Uilleann

> WHOA!!  How do they do that?  Like, they produce a lens from black matter or something, just plug in the Rx info and "SHAZAM!", there it is?
> 
> :bbg::bbg::bbg::cheers:


No no no.  *RED matter*.  GEEZE!  I swear did _NO_ one else watch the Star Trek movie?!  It's all spelled out there in 7.1 channel glorious Blu-ray high def now for your review.  I swear I have to do all the work around here.  *turning on TV once again*  "Honey - grab me another beer would ya?"  hehehe:D

----------


## Mr. Finney

> No no no.  *RED matter*.  GEEZE!  I swear did _NO_ one else watch the Star Trek movie?!  It's all spelled out there in 7.1 channel glorious Blu-ray high def now for your review.  I swear I have to do all the work around here.  *turning on TV once again*  "Honey - grab me another beer would ya?"  hehehe:D


Oops, my bad:o

----------


## Pete Hanlin

What a great thread! I feel like I'm bathing in knowledge....it feels kinda squidgee.....I likey!
Glad someone else is enjoying this thread! Optiboard is a great place to exchange information.

I was checking cylinder power availability for the Comfort and the Comfort 360 in the Frames Lens Guide. I see that the Comfort list cyl. power up to 4.00. The Comfort 360 lists cyl. power up to 6.00. I forget what material (1.67?). I don't have the guide at home to double check.

What I am having a hard time grasping is:
If the blank being used is the same, how can the 360 offer an extra 2.00 in cylinder power?
There's no red, black, or pink polka-dotted matter involved... just a boring story.

Our traditional surfacing charts (base curve charts) go up to 4.00 diopters- however, as long as the blank will support the curvature, your laboratory can place 6.00 or even 7.00 diopters of cylinder on the back surface if they wish.  Actually, this brings back a funny memory. When I managed US Market Quality for Essilor (a few years back), we had a lab that simply _refused_ to put over 4.00 of cylinder into a Varilux lens unless Essilor supplied them with an official document indicating it was okay to do so (guess we live in a litigious society :Rolleyes: ).  Anyway, I put together some special base curve charts that went up to 6.00 so the lab could fill an order (don't ask me where that chart is- that was a couple laptops ago). 

With DS products, its a little more involved. The nature of 360 Optimization means the biggest benefit will be noticed with patients who have cylinder, so I suppose we should have anticipated the requests that came in after launch (_"If 360 is so great for astigmats, why can't we go above 4.00 diopters?!?_"). 

Well, as previously mentioned, process control is the key to digital surfacing- so an Essilor DS lab can't just _"try"_ to create a power outside the range.  The laboratories in the Essilor laboratory network which offer DS processing have pretty strict parameters- including the Rx range. 

So, it took a special project to get the range increased.  Essilor has a group called "OTG" which tests/certifies laboratory processes, and they had to certify the DS process up to 6.00 diopters of cylinder (they run a bunch of lenses in different designs on different pieces of equipment to ensure design conformance and stuff).  I forget when the range expansion was added (end of '08 or somewhere around then), but our DS laboratories can now go up to 6.00 diopters of power (which is naturally limited by total power- going back to the thickness of the blank and all).  Naturally, marketing was quick to get the range extension onto the availability chart- even though the charts for the traditional products still read 4.00 diopters.

If your local laboratory won't provide high cylinder jobs, perhaps I can dig up the "special" base curve chart! :bbg:

----------


## YrahG

> On this point you are entirely mistaken. I'm not trying to be rude, but you seem resolute in stating Essilor does not use the back surface to modify a progressive front surface. In fact, I can cite several specific examples where Essilor uses two surfaces to acheive the final progressive design (generally speaking, we call this DDV- Dual Digital Vision... the front surface has a progression which has been molded and the back surface is used to modify that design and in some cases change it altogether).
> I'll try to give a few examples, but the main point is what I've repeatedly said- just because you have progression on the front of a lens doesn't mean you can't modify the design "on the fly" to any parameter of your choosing. Actually, this is mentioned in a Zeiss white paper on Zeiss Individual (Zeiss indicates they prefer a FBS format because it is difficult to align the two surfaces precisely... Essilor has spent considerable resources on equipment dedicated to aligning the sides).


I am glad you brought up the Zeis Individual white paper, I have said in the past if all manufacturers were to provide such great literature our profession would be in a eutopia. So far I have cited references to various data substantiating my thoughts. I have seen nothing to sugget the Physio Enhanced lens design is modified by the back surface unless we count delivering the intended design as modifying the design.

Here is a simple end all to this conversation. If the Physio Enhanced and the Phyio 360 for that matter is so customized for the pateint why is "position of wear" data not required?

Since you cited the Zeiss white paper here is a passage:

_"Therefore the position of wear can have significant impact upon the optical performance of a progressive lens, particularly the quality of vision through the central viewing_ _zones"_

I have attached an image I hope fair use applys here, it is from the Zeiss white paper. Darryl and Zeiss do a great job in simplifying the process, the imge shows the intended design and what happens to that design once a prescription is introduced. The zeiss paper shows the difference being subtracted from what is surfaced. I like to explain it to opticians as an Rx compensated for vertex you supply the lab with a prescription that is different than the prescribed prescription because when it is worn at the modified vertex it has the same optical effect as the prescribed prescritpion at the phoropters length. Now although Darryl does a great jobsimplifying this process and the image makes it looks like childs play, we are not working with lines, squares, or rectangles; we are working with curves spheres, cylinders, aspheric, atoric, and deformed conicoids. The image shows a surface being subtracted but in reality after this initial subtractin is done the design would without a doubt in my mind go through further iterations to make sure the difference between the intended design and the delivered design are within tolerance. I have seen "zero" evidence. I will repeat that "ZERO" evidence that suggests this new version of the Physio changes the intended design like you mention. 

Pete, please this is one time I would love to eat crow. Provide me with some resources that verify the design is customized to the "INDIVIDUAL" not the design. I like to fit my lenses to the patients needs, not change the patients needs to fit the designs I sell. I hope this is what seperates me from the pack.




> Digital surfacing is challenging to control because a.) variables in the process have a greater impact on the final product quality, and b.) it's harder to measure the accuracy of the final product. Several manufacturers are trying to develop equipment which can be used in the lab to measure the conformity of digitally surfaced lenses, but today most labs run test lenses in the morning and then trust the process is under control for the rest of the shift/day. Most of the major lens manufacturers have invested tons of money to ensure process control of their digital surfacing processes (which is why you see manufacturers creating big central DS labs where they can oversee the process). That's not to say local independent laboratories can't produce great digitally surfaced products, but it certainly helps if a manufacturer can provide process support (I know Zeiss and Essilor have certification processes for labs which digitally surface their lenses, I do not know what level of support is offered by Seiko, Kodak, and Shamir).


This is very good information, worth bookmarking this thread for. I have mentioned in previous threads that the any FF that incorporates the design component in the surfacing at the lab means that a manufacturer and their quality control which ensures the lab is recieving a blank that meets specs is removed. This is a check that we have grown acustomed to and the reputation of certain manufacturers have been built on the this quality assurance. 

Simply put, Poor Quality Lab = No FF Business.

This shoudl be a hard and fast rule, thsi means that all those offices looking for the best deal need to consider this process doesn't play well with cut corners so you really really really get what you pay for.




> Ah, so I'm glad to see our discussion is not over! :)
> Yes, the front surfaces of all the Varilux 360 PALs are molded. So are the front surfaces of FBS PALs! The difference is the front surface of an FBS PAL is spherical, and the front surface of a 360 PAL has progression on the front.


It's hard not to respond with you egging me on, like the sentence right after the smiley face. :finger:

Touche, a spherical moulded surface is still moulded just like a PAL surface, however see my previous posts about ISO standards, tighter tolerances require a SV mould to be more accurate. I am one of those kooks that believes that tighter tolerances are needed, especially with FF lenses. I also am optimistic that this will be a part of the next ANSI.




> Each PAL design has its own technologies and purposes, and yes- market niches to fill.


Love this statement, since ECPs (ODs, OMDs, and some Opticians) have knowledge of Seidel or secondary optics why is it information about PALs is still in our one demensional primary theory world. I would love to see a range of lenses that come from a manufacturer that vary in the aberrations they place the most merit with. For instance a lens with reduced marginal astigmatism as a primary design goal, another design from said company with reduced distortion or orthoptic design, etc. It could help fitters gain a better grasp on fitting and their patients needs.

----------


## Pete Hanlin

Here is a simple end all to this conversation. If the Physio Enhanced and the Phyio 360 for that matter is so customized for the pateint why is "position of wear" data not required?
First, I'll agree with you that Darryl does an excellent job describing Zeiss' technology.

Second, I'll also agree that better SFSV blanks would increase the accuracy of FBS designs.   I'll have to side with AWTECH regarding your discussion on tolerances, however.

Finally, you are changing your objection with each post.  Your first objection was that a blank with a progression on the front surface could not truly be "designed on the fly."  I believe I've given several examples that demonstrate that, yes- it can.  Now your objection is the nature of the customization. 

Incidentally, the graphic you posted is actually a good illustration of how 360 works- the design is altered to remove the negative impact of the distance Rx.  Of course, it is possible to take it a step further with "position of wear" customization- which is found in both Varilux Ipseo IV (available in the US) and Varilux Physio F-360 (a design available in Europe).  Both of these designs can be ordered with POW parameters.  In fact, Varilux Ipseo IV also personalizes the design to the wearer's visual habits, which is beyond anything that has been discussed here.

Position of wear is a legitimate way to customize a PAL, but for it to make a significant difference, the position of the lens has to deviate substantially from the norm (the norm being around 7 degrees of panto, 8 degrees of wrap, and 12-13mm vertex).  Its pretty rare when you can't fit a frame pretty close to these parameters (significant deviation from a normal fit only occurred in about 15% of a dataset of 50k+ orders I surveyed last year).  In another illustration from the Zeiss paper we've been citing, I think they show a lens with significant power (+3.00 or so with cyl) with quite a bit of wrap and tilt.  I'm not criticizing the illustration- merely pointing out you have to show a rather extreme example to demonstrate significant customization.  Also, the quality of the base design is going to be quite important as well- I can customize an Essilor Adaptar to POW, and it still isn't going to perform nearly as well as a Varilux Comfort.

To end the matter simply (as you put it), I know the wearer can see an improvement with the Rx customization in Varilux 360 Optimization products, because I can measure the improvement on actual subjects.   The original point of this thread concerned whether these design features result in any actual improvement.  The data indicates that- in the case of 360 Optimization at least- the answer is "yes."

My apologies if the smiley face offended you- it was meant in good humor (and I take your wagging finger in good humor as well).

I'll close my contributions to this thread with the following: Proper fitting increases the performance of a design more than any of the "extras" we've been discussing.  Seriously, it sounds as if you take great care in your fitting- and that's probably driving performance more than anything else you can do.  Of course, we all (manufacturers and practitioners alike) are trying to provide ever increasing levels of performance- and I think there's gains to be had in the approaches of Essilor, Zeiss, and other manufacturers.

Best regards,
Pete

----------


## OCP

> Digital lenses accurate to within 1/100th of a diopter...
> 
> I just had my Essilor rep in today pitching the new Physio Enhanced, supposedly it takes into consideration a given pupil diameter to optimize light transmittance...
> 
> Free-form this free-form that, thousands of free-form flavors...
> 
> I haven't matured yet to need PAL's yet but is there really, I MEAN REALLY, a noticeable difference between standard surfaced, digital surfaced and free-form produced PAL's. It seems that the industry is getting a little carried away.


Anyone proffesional and clever eye doctor and optician, knows that pupil size dosent matter when talking about glasses. Contact lenses is a different question.
I don´t know if the mention Physio Enhanced is a better lens than previous design, but if it is, it´s for sure not because of the pupil size, but many will get that feeling only because it works better (if it does so).
We are therefor buying the _story_ behind the lens.

As I have  said many times, the industry (the design teams) will keep up invention new stories to sell their new lens designs, and it´s sometimes not fair for the sale rep, because they have to defend these stories with the knowledge that the story is not true in real life. Actually the design teams very often succes to convince their sales rep these invented stories.
Bad for our general knowledge.

Pete you got a hard job and will always be in crossfire because of this. 
I fell with you.

Mike

----------


## Pete Hanlin

Pete you got a hard job and will always be in crossfire because of this.
Actually, I have a _challenging_ job- which is what makes it fun, and frustrating at times.  :)
Seriously, my grandfather (who grew up in the Great Depression- so he had a pronounced appreciation of steady employment) gave me a little sign that hung on his cubicle (he worked as a Warrant Officer in the Pentagon for a number of years) that says _"Thank God for the Troubles in Your Job."_  The main message being, if it weren't for the challenges of your particular job, ANYONE could be found to do the job at half of what they're probably paying you- so be thankful for challenges, because they pretty much account for your salary.  Let's just say that- over the 7 years I've been working for Essilor, I've had several opportunities to be thankful! 

Anyone professional and clever eye doctor and optician, knows that pupil size dosen't matter when talking about glasses. Contact lenses is a different question.
If you had said _"the higher order aberrations within the eye do not matter when talking about glasses"_ you would have been mostly correct- because while you can resolve some higher order aberrations within the eye with a contact lens, an eyeglass lens cannot be used to resolve higher order aberrations within the eye.  I say mostly because Zeiss is currently taking the impact of higher order aberrations within the eye into account when filling a lower order Rx.  Also, technically speaking, if you can tolerate them I would imagine the best form of ophthalmic correction possible is found in a rigid gas permeable lens (which resolves irregularities on the cornea with a tear lens).

Regarding pupil size, however...  From an optics perspective- pupil size has greater impact on the performance of an eyeglass lens than on a contact lens.  I am not an expert in contact lenses, but as I recall the size of the pupil plays a role in determining the proper geometry of the CL (i.e., larger pupils require contact lenses with a larger diameter- either diameter of zone or physical diameter.

There are several reasons why this is true, but the first lies in the vertex distance between the lens stop (pupil) and the lens in question.  In a contact lens, the vertex is pretty small- a CL sits about 3mm in front of the pupil iris (as I recall the anterior chamber is about 3mm deep- correct me if I'm mistaken).  An eyeglass lens sits about 15mm in front of the iris.  

The relevance of all this is seen when we ray trace light "backwards" from the retina out the front of the eye.  Since a lens focuses light on the retina, we will see the light diverging as it leaves the retina towards the lens stop.  The light making it through the aperature is still diverging, and in 3mm it will meet the cornea where we can measure its diameter.  In another 12mm or so our rays will meet the back of the eyeglass lens- where it will form a _larger_ diameter.  

As the diameter becomes larger, it becomes harder to control the optics.  To illustrate, we all know that anyone (with otherwise healthy eyes) will have 20/20 vision looking through a pinhole- regardless of refraction (because only one ray of light travels through the pinhole, and it is unrefracted).  As the hole is increased in size, a greater column of rays passes through the lens stop- and any aberrations in the system become more apparent.  Therefore, if an eyeglass lens has aberrations, those aberrations will become more apparent (at a faster rate than with contact lenses due to the relative vertices) as the pupil size increases.

In the distance portion of the lens, Varilux Physio is designed to control (eliminate or greatly reduce) higher order aberrations across a diameter on the lens that corresponds to a 6mm pupil size.  In Varilux Physio Enhanced, higher order aberrations are controlled for an 8mm pupil size.  Assuming this control actually occurs, we would expect individuals wearing the two lenses to notice sharper vision in low light conditions (and in fact wearers do significantly prefer Varilux Physio Enhanced over Varilux Physio in dim lighting conditions (p=<0.01).

----------


## YrahG

> Finally, you are changing your objection with each post. Your first objection was that a blank with a progression on the front surface could not truly be "designed on the fly." I believe I've given several examples that demonstrate that, yes- it can. Now your objection is the nature of the customization.


If you are changing the definition of design on the fly then your right it is me that is misinforming on this thread.





> Incidentally, the graphic you posted is actually a good illustration of how 360 works- the design is altered to remove the negative impact of the distance Rx. Of course, it is possible to take it a step further with "position of wear" customization- which is found in both Varilux Ipseo IV (available in the US) and Varilux Physio F-360 (a design available in Europe). Both of these designs can be ordered with POW parameters. In fact, Varilux Ipseo IV also personalizes the design to the wearer's visual habits, which is beyond anything that has been discussed here.


I have mentioned the Ipseo as a truly inovative leap in PAL technology and your right that is a whole nother discussion in and of itself.  I'll just sum p the Ipseo as the only lens that incoproates a patieents visual habts into the lens design in the form of a ratio feed into the design software known as the "gain" which is a reference to the ratio of head to eye movement when viewing off axis objects.  This means the DESIGN IS CUSTOMIZED to meet the patients needs.




> the design is altered to remove the negative impact of the distance Rx.


I am truly in awe.  Either I neew a definition to what design truly means or youd do.  Since there always exists the possibility that it might be me that is misinformed.  I will conced in this, your lens DESIGN does get cleaned up on the back surface to deliver what was intended but the intended design was chosen by Varilux and the patient needs to fit that DESIGN.  I like the Zeiss Individual sicne it will allow me to put my patient first and actually fits the DESIGN to my patients parameters.

Pete, 

I do not feel sorry for you at all, I am not trying to give you or your product a hard time just trying to cut the fat fromt he meat.  Matter of fact I envy a position such as yours, you get access to unadulterated data.  To me this access is the holy grail.

----------


## OCP

> Pete you got a hard job and will always be in crossfire because of this.
> Actually, I have a _challenging_ job- which is what makes it fun, and frustrating at times.  :)
> Seriously, my grandfather (who grew up in the Great Depression- so he had a pronounced appreciation of steady employment) gave me a little sign that hung on his cubicle (he worked as a Warrant Officer in the Pentagon for a number of years) that says _"Thank God for the Troubles in Your Job."_  The main message being, if it weren't for the challenges of your particular job, ANYONE could be found to do the job at half of what they're probably paying you- so be thankful for challenges, because they pretty much account for your salary.  Let's just say that- over the 7 years I've been working for Essilor, I've had several opportunities to be thankful! 
> 
> Anyone professional and clever eye doctor and optician, knows that pupil size dosen't matter when talking about glasses. Contact lenses is a different question.
> If you had said _"the higher order aberrations within the eye do not matter when talking about glasses"_ you would have been mostly correct- because while you can resolve some higher order aberrations within the eye with a contact lens, an eyeglass lens cannot be used to resolve higher order aberrations within the eye.  I say mostly because Zeiss is currently taking the impact of higher order aberrations within the eye into account when filling a lower order Rx.  Also, technically speaking, if you can tolerate them I would imagine the best form of ophthalmic correction possible is found in a rigid gas permeable lens (which resolves irregularities on the cornea with a tear lens).
> 
> Regarding pupil size, however...  From an optics perspective- pupil size has greater impact on the performance of an eyeglass lens than on a contact lens.  I am not an expert in contact lenses, but as I recall the size of the pupil plays a role in determining the proper geometry of the CL (i.e., larger pupils require contact lenses with a larger diameter- either diameter of zone or physical diameter.
> 
> ...


Hi Pete

I fully agree with challenges. Without challenges I would personal be bored to death. 

Back to pupil size. I agree a normal persons vision will be better/sharper with smaller pupil size, thats what we call the pinhole effect. But how in the whole world can you use this knowledge to anything in a fixed lens design?
-unless you make the pinhole effect in your lens, as I don´t think you do.

Because the pupil size are not an fixed value you cant take this into account in a fixed lens design.

What is default pupil size? 6 mm?
Can you make an better lens design if the pupil size is 4 or 8 mm? 
If you actually could do that, why don´t you just use that specific design for all pupil sizes.?

I see other more important issues in a progressive lens design, such as handling of abberations, lower astigmatic deviation and better handling of the aspherical design.

But this is so boring parameters and I think the design teams are to much focused on more hyped trivial features to get the attention from the opticians around the world.

Mike

----------


## YrahG

> Hi Pete
> 
> I fully agree with challenges. Without challenges I would personal be bored to death. 
> 
> Back to pupil size. I agree a normal persons vision will be better/sharper with smaller pupil size, thats what we call the pinhole effect. But how in the whole world can you use this knowledge to anything in a fixed lens design?
> -unless you make the pinhole effect in your lens, as I don´t think you do.
> 
> Because the pupil size are not an fixed value you cant take this into account in a fixed lens design.
> 
> ...


The pupil size has an effect on the spherical aberration and coma present, however to reduce these two aberrations the cost is less emphasis on other aberrations such as marginal astigmatism and distortion.  Every manufacturer has their own so called recipe as to which aberrations are more important then others.  You like Coke, but that doesn't make it better than Pepsi, if we can come to an understanding that people are as individual in their viewing tasks and preferences as they are in their taste for soft drinks then it becomes evident that their really cannot be a one great PAL lens but a portfolio of offereings that all complement each other.  This can help an office offer an eyewear experience that is unparalleled.

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## scriptfiller

Pete,

Are the optics in the Physio enhanced optimized (better corrected) for larger pupil diameters.  I know from the photographic industry that lenses with f ratios less than 3 the optics in the lense have to be made to higher standards due to the fact that a larger more corrected lenses are needed to transmit the added light to the photosite without vignetting, coma and CA.  An F/2.8 lense will allow more light than an F/3.5 lense.

----------


## Pete Hanlin

Unfortunately, I won't have as much time this week to respond to this thread.  However, I've tried to put together two images in an attempt to quickly explain the role of pupil size...

In an optical system, the size of the lens stop is connected to the perception of aberrations.  In fact, this is why coma is usually not a significant issue (because the size of the pupil minimizes the impact of coma).  However, many PALs have significantly more coma around the PRP/FRP due to the changing curvature of the lens surface.  

Again, if the pupil is small the issue is minimized.  However, in distance viewing (and in dim lighting) the pupil dilates- which increases the area of the lens being used (and therefore the impact of any aberrations present in the system).  

The first graphic attached illustrates the perception of the wavefront at different pupil sizes.  When the pupil is small, the impact will be minimal (if the pupil constricted to a pinhole, the impact of any aberrations in the system would be completely removed).  As the pupil dilates (either due to dim light or by looking in the distance), aberrations in the lens have a larger impact on the wavefront perceived by the eye.

When this happens, the MTF value of the lens is reduced (the image produced by the lens has less contrast than the object being viewed).  The result is a reduction in contrast perception (and perceived image sharpness).  

The second graphic illustrates some concepts we haven't even touched on- namely the alignment of astigmatism in the immediate intermediate periphery and the control of power in the near.  The alignment of astigmatism in the intermediate periphery will impact the perception of width (assuming you do not require cylinder, try putting 0.50D of cyl in each eye of the phoropter...  place both axes at 90, and I bet the results aren't very disturbing to your vision- now try placing the axes at opposing diagonals... a bit more disturbing).

There are two concepts that differentiate Varilux Physio Enhanced from the original Varilux Physio.  First, in the distance the wavefront is controlled out to a diameter of 8mm vs. 6mm.  Second, the "pattern" of wavefront correction (the mapping of the pupil sizes controlled) is changed from lens to lens to best suit the patient's Rx, approximate age, visual distance, and the worst anticipated lighting condition in each zone.

_"Why not just control to 8mm everywhere?"_ is a legitimate question.  Higher order aberrations are somewhat similar to lower order aberrations (astigmatism), in that you can't totally eliminate them- at best you can control them more in specific areas than others.  In short, Varilux Physio Enhanced has a "multi-design" approach to how higher order aberrations are controlled.  BTW, control of higher and lower order aberrations are not mutually exclusive (you can do both at the same time).  However, both have to exist- you can't just totally eliminate both.

Not much time to go back and edit this post- lots to do today.  Hopefully, however, this answers some of the questions regarding the impact of pupil size on vision in a PAL.

----------


## Pete Hanlin

Oh, and by the way- as YrahG suggested, I have an _awesome_ (if sometimes challenging) job.  If you've ever watched _Working Girl_, the conclusion of the movie sums up quite well how I feel about my job (cue the _"Let the River Flow"_ music- although my hair isn't quite as "big" as Melanie Griffith's :)).  Each day I get to think about what concepts/products we'd like to test (I would have KILLED to have this ability when I was still dispensing).

In fact, that's what I have to go do now- work on summarizing some data from a study...

----------


## OCP

> Unfortunately, I won't have as much time this week to respond to this thread.  However, I've tried to put together two images in an attempt to quickly explain the role of pupil size...
> 
> In an optical system, the size of the lens stop is connected to the perception of aberrations.  In fact, this is why coma is usually not a significant issue (because the size of the pupil minimizes the impact of coma).  However, many PALs have significantly more coma around the PRP/FRP due to the changing curvature of the lens surface.  
> 
> Again, if the pupil is small the issue is minimized.  However, in distance viewing (and in dim lighting) the pupil dilates- which increases the area of the lens being used (and therefore the impact of any aberrations present in the system).  
> 
> The first graphic attached illustrates the perception of the wavefront at different pupil sizes.  When the pupil is small, the impact will be minimal (if the pupil constricted to a pinhole, the impact of any aberrations in the system would be completely removed).  As the pupil dilates (either due to dim light or by looking in the distance), aberrations in the lens have a larger impact on the wavefront perceived by the eye.
> 
> When this happens, the MTF value of the lens is reduced (the image produced by the lens has less contrast than the object being viewed).  The result is a reduction in contrast perception (and perceived image sharpness).  
> ...


Hi Pete

Thanks for details concerning Pupil size.
I need to ask you. How and under which lighting conditions do you measure the pupil size?
Does this lens work only for people with chronic reduced pupil effect?

Normal pupil size goes from 3-6,5 mm in size in a day. Will this lens be delivered with an automatically battery function to change the design?

-I´m not kidding.


Mike

----------


## YrahG

> Hi Pete
> 
> Thanks for details concerning Pupil size.
> I need to ask you. How and under which lighting conditions do you measure the pupil size?
> Does this lens work only for people with chronic reduced pupil effect?
> 
> Normal pupil size goes from 3-6,5 mm in size in a day. Will this lens be delivered with an automatically battery function to change the design?
> 
> -I´m not kidding.
> ...


The distance is designed for the worst case scenario with an 8mm pupil size, howver due to the constriction of the pupil during up close viewing task, the constriction and reduction in range of pupil size due to age, and otehr factors that effect the pupil size the intermediate and the near zones are optimized to smaller pupil diameters which allows Varilux to move some of that aberration control to other more important aberrations in those particular zones.  I think the idea is interesting, I have been successful with the Physio products and see it as a significant step above the Comfort and Panamic.  I just can't help but to feel that it could be better on the back side, luckily that will be available in the 3rd quarter this year.




> Oh, and by the way- as YrahG suggested, I have an _awesome_ (if sometimes challenging) job.  If you've ever watched _Working Girl_, the conclusion of the movie sums up quite well how I feel about my job


I have never seen "Working Girl", but it made me laugh thinking that you feel like the conclusion to a movie called "Working Girl".  Please don't post any pictures.:D  Ok now I'm giving you a hard time.....j/k

----------


## Pete Hanlin

I need to ask you. How and under which lighting conditions do you measure the pupil size?  Does this lens work only for people with chronic reduced pupil effect?  Normal pupil size goes from 3-6,5 mm in size in a day. Will this lens be delivered with an automatically battery function to change the design?
No measurement of the individual's pupil size is required.  Each Varilux Physio Enhanced lens controls the wavefront to various pupil diameters (ranging from around 8mm to 4mm) in a pattern that is determined by several factors:
*Age-* As the eye ages, the pupil size decreases slightly.  The approximate age is taken from the ADD power (since ADD and age roughly correlate).
*Rx-* Due to refractive effects, the "effective pupil size" of a hyperope is larger than that of a myope.  Even though a myope and hyperope may have the same size pupil, the area of the lens being viewed is larger for a hyperope-  I think this was discussed earlier in the thread.
*Viewing Distance-* The pupil constricts when viewing near objects.  Based on the power at each point in the lens, the focal length can be converted into the viewing distance, which can be used to determine the largest pupil size likely to exist when using a specific location on the lens.
*Lighting Condition-* Of course the lens doesn't know what lighting condition it is in at any given moment- but there are some assumptions that can be made regarding the _worst_ likely lighting conditions the wearer will encounter at each viewing distance.  In distance vision, the worst condition is likely to be quite dark (thus the worst case assumption of 8mm in the distance).  In near vision, the worst condition is likely to be dim light (people can't/don't read in darkness- thus the 4mm at near).

Pupil sizes vary from one person to another- however, by knowing the person's age and Rx the "map" of the pupil sizes the patient is _likely_ to have at different points in the lens can be moved around to a pattern most _likely_ to correspond to the patient.  The differences between Varilux Physio and Varilux Physio Enhanced are a.) there is "better" correction of the wavefront in Enhanced (larger diameters are controlled), and b.) greater attention is placed to the likely pupil size of each wearer at each location in the lens.

Keep in mind a.) if the controlled area is larger than the patient's actual pupil size- that's fine (being over isn't a problem), and b.) even if you have a patient with abnormally large pupils, Varilux Physio Enhanced still has better wavefront control than any other lens available (so there aren't any other lenses out there that are going to provide a "cleaner" wavefront to the patient).  The goal of all this wavefront stuff is to provide sharper vision in all lighting conditions and all distances.  I've posted another pic to explain the difference in approach between Varilux Physio and Varilux Physio Enhanced.  The contours of the pupil size on the Varilux Physio Enhanced will change somewhat depending on the factors listed above.

Yesterday, I was summarizing the results of a study that was completed a week or so ago.  In the study, the overall performance of Varilux Physio Enhanced lenses was compared to Varilux Physio lenses.  Although a poster on the results will be available shortly, the study had three interesting findings: 
1.) In "standard lighting" (100 cd/m2), 71% of the subjects who had a preference preferred Varilux Physio Enhanced.  
2.) In "dim lighting" (25 cd/m2), the preference for Varilux Physio Enhanced was significant (p=0.006).
3.) In the subject comments, the most frequent comment was _"these are sharper/clearer/more focused"_ (the wearer doesn't know which lens is which- but that's how they described the Varilux Physio Enhanced lenses). 

_THAT'S_ why I'm confident WAVE Technology 2 works...  Given the main feature of the design is wavefront control, the fact that the preference increases in dim light (when the pupil is larger and the eye is more likely to notice wavefront aberrations) correlates with the MTF measurements that have been made on the lenses, and confirms that a practitioner should have good success with Varilux Physio Enhanced in real life.  In particular, for people who complain about their vision in dim light (which is, I recall, a significant % of patients) Varilux Physio Enhanced lenses should be a good solution.

----------


## OCP

> I need to ask you. How and under which lighting conditions do you measure the pupil size?  Does this lens work only for people with chronic reduced pupil effect?  Normal pupil size goes from 3-6,5 mm in size in a day. Will this lens be delivered with an automatically battery function to change the design?
> No measurement of the individual's pupil size is required.  Each Varilux Physio Enhanced lens controls the wavefront to various pupil diameters (ranging from around 8mm to 4mm) in a pattern that is determined by several factors:
> *Age-* As the eye ages, the pupil size decreases slightly.  The approximate age is taken from the ADD power (since ADD and age roughly correlate).
> *Rx-* Due to refractive effects, the "effective pupil size" of a hyperope is larger than that of a myope.  Even though a myope and hyperope may have the same size pupil, the area of the lens being viewed is larger for a hyperope-  I think this was discussed earlier in the thread.
> *Viewing Distance-* The pupil constricts when viewing near objects.  Based on the power at each point in the lens, the focal length can be converted into the viewing distance, which can be used to determine the largest pupil size likely to exist when using a specific location on the lens.
> *Lighting Condition-* Of course the lens doesn't know what lighting condition it is in at any given moment- but there are some assumptions that can be made regarding the _worst_ likely lighting conditions the wearer will encounter at each viewing distance.  In distance vision, the worst condition is likely to be quite dark (thus the worst case assumption of 8mm in the distance).  In near vision, the worst condition is likely to be dim light (people can't/don't read in darkness- thus the 4mm at near).
> 
> Pupil sizes vary from one person to another- however, by knowing the person's age and Rx the "map" of the pupil sizes the patient is _likely_ to have at different points in the lens can be moved around to a pattern most _likely_ to correspond to the patient.  The differences between Varilux Physio and Varilux Physio Enhanced are a.) there is "better" correction of the wavefront in Enhanced (larger diameters are controlled), and b.) greater attention is placed to the likely pupil size of each wearer at each location in the lens.
> 
> ...


Pete I understand you quite well, but don´t believe the higher satisfaction level was according to the pupil size.
In my humble opinion, it´s because of an upgraded Physio design in general.
Shamir, and others, could make the same study between the Autograph Classic and the Autograph II and claim something like the lens are taking into account the depth of the eyeball and thats the reason that more clients prefer this lens. I don´t claim you personal, I just have my doubts that taking the pupil size into account in a lens, could have *anything* to do with the improved vision. That is simple not logic and realistic. In my world, it´s another fabricated story to sell a new (and maybe improved) lens.

Annoying Mike :shiner:

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## Pete Hanlin

Please don't post any pictures.:D
Okay, so you just _know_ I have to post a picture... ;)
Tess McGill- the humble secretary who became a financial analyst on Wall Street!


Welcome to the 1980s!  It was a good decade to own stock in hairspray manufacturing!

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## YrahG

> I don´t claim you personal, I just have my doubts that the pupil size could have *anything* to do with the improved vision. That is simple not logic and realistic. In my world, it´s another fabricated story to sell a new (and maybe improved) lens.
> 
> Annoying Mike :shiner:


You may need to hit the books as everything said in Pete's post you referenced is fairly accurate and very logical.

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## YrahG

> Please don't post any pictures.:D
> Okay, so you just _know_ I have to post a picture... ;)
> Tess McGill- the humble secretary who became a financial analyst on Wall Street!
> 
> 
> Welcome to the 1980s!  It was a good decade to own stock in hairspray manufacturing!


That clears up a lot, I was thinking more the "Pretty Woman" type working girl. ;):p:D

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## OCP

> You may need to hit the books as everything said in Pete's post you referenced is fairly accurate and very logical.


I did already read my books again, and still dont find anything that could justify this claim.
-and it´s not logical, it sounds good (the design teams are usual great to fabricate these stories) but it´s absolutely not logical and realistic at all.
Sorry.

I will look more and try to find any evidence that could prove your claims. -I don´t think anyone can find this hidden treasure that don´t exist.

Mike

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## HarryChiling

Thank you Pete and others for this lively discussion, helps to seperate the fluff from the stuff.

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## YrahG

> I did already read my books again, and still dont find anything that could justify this claim.
> -and it´s not logical, it sounds good (the design teams are usual great to fabricate these stories) but it´s absolutely not logical and realistic at all.
> Sorry.
> 
> I will look more and try to find any evidence that could prove your claims. -I don´t think anyone can find this hidden treasure that don´t exist.
> 
> Mike


They are not claims, those points truly were facts.

Attached you will find excerpts from books in my library that discuss these concepts.

1st image discusses the pupil range and how anything larger than 5mm may see reduced acuity due to spherical aberration.2nd image talks abotu the effects of illuminace on the constriction of the pupil.3rd image references smaller pupil diameters as a result of age.4th image defines spherical aberration and uses the term aperature which in our optical system is the pupil.5th image defines coma and uses the term aperature which in our optical system is the pupil.I only used two book that I knew had references off the top of my head, but I could pull more if necessary.  It is hard enough trying to get to the facts please verify your facts before posting them I am trying to have a serious discussion on the subject.

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## OCP

> They are not claims, those points truly were facts.
> 
> Attached you will find excerpts from books in my library that discuss these concepts.
> 
> 1st image discusses the pupil range and how anything larger than 5mm may see reduced acuity due to spherical aberration.2nd image talks abotu the effects of illuminace on the constriction of the pupil.3rd image references smaller pupil diameters as a result of age.4th image defines spherical aberration and uses the term aperature which in our optical system is the pupil.5th image defines coma and uses the term aperature which in our optical system is the pupil.
> I only used two book that I knew had references off the top of my head, but I could pull more if necessary.  It is hard enough trying to get to the facts please verify your facts before posting them I am trying to have a serious discussion on the subject.


Ohh my good. 
This is not what I am talking about, and you should know that. 
No one here can argue against these fact that most of us learned 25 years ago, and I have never tried to do so, but you still need to tell me how you can use this anatomy knowledge in a optical lens.! 
These facts is okay in a medical perspective, but you still need to convince me, and 10.000 others, how in heaven this can be used in a fixed lens design. 

Mike

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## YrahG

> These facts is okay in a medical perspective, but you still need to convince me, and 10.000 others, how in heaven this can be used in a fixed lens design. 
> 
> Mike


The only thing I need to do is die and that is also a function of age.:D




> I just have my doubts that taking the pupil size into account in a lens, could have *anything* to do with the improved vision. That is simple not logic and realistic. In my world, it´s another fabricated story to sell a new (and maybe improved) lens.


That is a direct quote of yours, I showed you more than *anything* I hope.




> Pete I understand you quite well, but don´t believe the higher satisfaction level was according to the pupil size.


If that is the only thing changed in the design, then either it is the reason or they got a particularly frisky bunch in their testing.




> This is not what I am talking about, and you should know that. 
> No one here can argue against these fact that most of us learned 25 years ago..........................................These facts is okay in a medical perspective, but you still need to convince me, and 10.000 others, how in heaven this can be used in a fixed lens design.


Before I go into explanation of how this factors in please let me know if this rudimetry explanation will insult your inteligence, because this too is in books that I could quote?

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## OCP

> The only thing I need to do is die and that is also a function of age.:D
> 
> 
> 
> That is a direct quote of yours, I showed you more than *anything* I hope.
> 
> 
> 
> If that is the only thing changed in the design, then either it is the reason or they got a particularly frisky bunch in their testing.
> ...


Okay, but ones again. How can you use a variable value as the pupil size in a fixed lens design?
Under which light conditions will you measure the pupil.?
Do you know if the client works in white clinic or in a coal mine? Do you know if the client is a night worker or a day worker? I´m sure this will make an influence of the size of the pupil in a daily basis?
If the design will be better in a given pupil size, then it will be worse in another pupil size.
etc, etc.

My point is that this is absolutely meaningless.

Mike

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## YrahG

> Okay, but ones again. How can you use a variable value as the pupil size in a fixed lens design?
> Under which light conditions will you measure the pupil.?
> Do you know if the client works in white clinic or in a coal mine? Do you know if the client is a night worker or a day worker? I´m sure this will make an influence of the size of the pupil in a daily basis?
> If the design will be better in a given pupil size, then it will be worse in another pupil size.
> etc, etc.
> 
> My point is that this is absolutely meaningless.
> 
> Mike


The pupil size is fixed for each zone but the size varies depending upon the zone. Although their is no way of predicting the amount of light that a person is going to be subjected to their are ways of guestimateing the data. 

For instance one that has already been addresses is the age. If you told me an add power I am confident that I would be able to guess the persons age 90% of the time or better within +-3 years.

I can make an assumption that the lighting in an office will be 30 to 50 footcandles. Using the Advanced Energy Design Guide http://resourcecenter.pnl.gov/cocoon.../article//1427
using this data and additional research can prove to be beneficial in estimating a pupil size optimal for the reading zone.

The Rx is supplied by the ECP so no need to guess at that, plus dependeing on base curve you can guestimate a range of Rx's in the design since the design is on the front surface.

Viewing distance doesn't need to be estimated since we know the distance should be optimized for 20ft and the near zone should be optimized for 14 to 16 inches leaving everything between as a function of the add power.

Now keep in mind this is my quick estimation of these variables and it is inresponse to a post, imagine what could be done with vast resources and scientists available to refine these variables. I don't question at all that this is the reason fro the improvement of the design. I do however question the degree of benefit from these improvements. 




> The 30% claim on Varilux Physio is related to the design (specific comparison is to Varilux Panamic) and has been demonstrated on actual wearers.


I think it was telling that the 30% claim of wider zones was in comparison to the Panamic which is being discontinued.  I don't think a reference to an irrelivant design is a good claim.

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## Mr.Powers

"If you told me an add power I am confident that I would be able to guess the persons age 90%"

i hav a Client whit Add : 2.50 ...............Guess his Age you can..... young Padawan.

Ofcoars you cant he can be from 60-100 years old but the degreasing of the pupil dont stop at 60 years so it is ones again BS from the  Lens Manufactors.


best regards

Peter

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## OCP

> The pupil size is fixed for each zone but the size varies depending upon the zone. Although their is no way of predicting the amount of light that a person is going to be subjected to their are ways of guestimateing the data. 
> 
> For instance one that has already been addresses is the age. If you told me an add power I am confident that I would be able to guess the persons age 90% of the time or better within +-3 years.
> 
> I can make an assumption that the lighting in an office will be 30 to 50 footcandles. Using the Advanced Energy Design Guide http://resourcecenter.pnl.gov/cocoon.../article//1427
> using this data and additional research can prove to be beneficial in estimating a pupil size optimal for the reading zone.
> 
> The Rx is supplied by the ECP so no need to guess at that, plus dependeing on base curve you can guestimate a range of Rx's in the design since the design is on the front surface.
> 
> ...


I agree that you can asume some data if you know the age of the client, or the addition.
But you can only *asume* these things, and we are talking about *FACTS*.
You are on very thin ice here to claim that you/Essilor can make an individual and improved lens, only by measuring the size of the pupil.

How many in this forum does actually think that measuring the pupil size will noticeable improve the vision? We are talking about peripheral abberations in the cornea in a ultra super small amount, that is only measurable with laser equipment in dark light (or other high end equipment). Please anyone ask question.

Mike

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## YrahG

> "If you told me an add power I am confident that I would be able to guess the persons age 90%"
> 
> i hav a Client whit Add : 2.50 ...............Guess his Age you can..... young Padawan.
> 
> Ofcoars you cant he can be from 60-100 years old but the degreasing of the pupil dont stop at 60 years so it is ones again BS from the Lens Manufactors.
> 
> 
> best regards
> 
> Peter


 
Your right but if I was looking for the largest pupil size as the worst case scenario it wouldn't matter if the pupil continued to decrease or not. Their literature does mention the largest size aperature as 8mm and the smallest as 2mm, so either way the smallest diamter used will be 2mm.




> I agree that you can asume some data if you know the age of the client, or the addition.
> But you can only *asume* these things, and we are talking about *FACTS*.
> You are on very thin ice here to claim that you/Essilor can make an individual and improved lens, only by measuring the size of the pupil.


I did not say individual, I did say improved. Matter of fact if you have been reading my posts I am very skeptical of the lens being called customized, apparently the definition of customized may have been changed to suit Essilors needs.




> How many in this forum does actually think that measuring the pupil size will noticeable improve the vision?





> I don't question at all that this is the reason fro the improvement of the design. I do however question the degree of benefit from these improvements.






> power errormarginal astigmatismdistortionspherical aberrationcomaOf the seidel aberrations I would rank them in the order above as to their importance. The pupil size is small enough that spherical aberration and coma are negligable similar to your example on the benefits from the potential accuracy gain from 0.06D rounding to 0.01D rounding (again notice I said potential).


I agree with you here and have from the beginning, I don't know if this will make a noticeable improvement or not. I have also ranked the aberrations in the order I see as the most beneficial. I am not interested in anyones opinions I am interested in facts. Many of the facts were laid out in this thread so it has served it's purpose, statements like the following:




> so it is ones again BS from the Lens Manufactors.


There is a lot of BS in this industry if your just now realizing it welcome to the world. Consider this your competitor and you both think you are the best, one of you is BS'ing.




> But you can only *asume* these things, and we are talking about *FACTS*.


Well then we will never get anywhere since this is optical theory we are dealing with and fromt eh start we are making assumptions that our understanding of optics is a fact.




> Shamir, and others, could make the same study between the Autograph Classic and the Autograph II and claim something like the lens are taking into account the depth of the eyeball and thats the reason that more clients prefer this lens.


You seem to have an axe to grind. I get it you like Shamir over Essilor. I agree but also think that my clients deserve the best available so it is my responsibility to learn the facts about all available designs *BEFORE* making my decision which lens will best suit the pateints needs.  

To do that I need to listen and learn, I was trying to provide some insight into how the lens might work, but it seems you are not interested so I will just quite down and lurk instead of participate until the next new lens design comes out.

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## OCP

> Your right but if I was looking for the largest pupil size as the worst case scenario it wouldn't matter if the pupil continued to decrease or not. Their literature does mention the largest size aperature as 8mm and the smallest as 2mm, so either way the smallest diamter used will be 2mm.
> 
> 
> 
> I did not say individual, I did say improved. Matter of fact if you have been reading my posts I am very skeptical of the lens being called customized, apparently the definition of customized may have been changed to suit Essilors needs.
> 
> 
> 
> 
> ...


Okay, I will try to put this down on paper.
What we are talking about here (just to make sure everyone and my self understand prober) is the distortion the Cornea create in the peripheral part of cornea (that is aprox. 2 mm from the center). In the theory it can be possible to compensate for the distortion in the lens IF THE PERSON IS ALLWAYS LOOKING STRAIHGT AHEAD, AND IF YOU KNOW HOW THE DISTORTION IS CREATED. 
But what will happens is you turn the eye a bit away from the center and look through the part of the lens where you made the compensation?
My point is that this feature is not possible and ones again an created story from the industry, (I will eschew to call it BS).
Mike

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## Fezz

*********Stretch-----------_YAWN_-----------Stretch*********

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## YrahG

> Okay, I will try to put this down on paper.
> What we are talking about here (just to make sure everyone and my self understand prober) is the distortion the Cornea create in the peripheral part of cornea (that is aprox. 2 mm from the center). In the theory it can be possible to compensate for the distortion in the lens IF THE PERSON IS ALLWAYS LOOKING STRAIHGT AHEAD, AND IF YOU KNOW HOW THE DISTORTION IS CREATED. 
> But what will happens is you turn the eye a bit away from the center and look through the part of the lens where you made the compensation?
> My point is that this feature is not possible and ones again an created story from the industry, (I will eschew to call it BS).
> Mike


You have been following the wrong thread, the spherical aberration being talked about is on the surface of the lens, the front surface to be exact.  Nothing to do with the cornea.  The pupil size is only relevent because it will determine the amount of rays that can enter at any one time, hence sph abe and coma.

At this point it really seems like you are more intent to be right than to discuss the facts and potential benefits (again I said potential).  I don't have the time to teach you optics and you don't seem to have the patience to read a book, so we are at an impasse.

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## xiaowei

> Again, if the pupil is small the issue is minimized. However, in distance viewing (and in dim lighting) the pupil dilates- which increases the area of the lens being used (and therefore the impact of any aberrations present in the system).


Hmmm, actually that the pupil generally dilates in certain distance range, especially for distant viewing, is totally new to me. I would more likely assume it depends on the "attention" the viewer pays to the object of interest, as also Wikipedia cites it here:

_The_ _Task-evoked pupillary response__ is the tendency of pupils to dilate slightly in response to loads on working memory, increased attention, sensory discrimination, or other cognitive loads[4]._

*4. ^*_ Beatty, Jackson; Brennis Lucero-Wagoner (2000). "The Pupillary System". in John T. Cacioppo, Gary Berntson, Louis G. Tassinary (eds.). Handbook of Psychophysiology (2 ed.). Cambridge University Press. pp. 142162. ISBN 052162634X._ 

which can also occur when viewing near objects!

Lighting is a totally different issue, however also here the retina does the main work, as is usually assumed, as the pupil area in older subject might only change by about 1:8^2 ~ 1:60, while the visual system can adopt to lighting conditions over say 1:100000!

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## Quantrill

So both the Physio and Physio Enhanced provide the sharpest vision.  It seems like the only reason to upgrade someone into the Enhanced is if they are consistently in low-light conditions?

From variluxusa.com - 

Varilux Physio and Varilux Physio Short lenses are ideal for:
 Patients who want the sharpest vision at every distance. 

Varilux Physio Enhanced lenses are ideal for:
Patients who want the sharpest vision at every distance and in every light condition especially low-light  

I guess my question is - is this just a marketing ploy or is there actually a reason to push the Enhanced?

Or I suppose I could sell 100% Ipseo (but then would I be depriving them of the sharpest vision at every distance?).

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## Mr.Powers

Who does the refraction in USA ? are optometrist Educated to do that or only Eye doctors ?



best regards

Peter

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## OCP

> You have been following the wrong thread, the spherical aberration being talked about is on the surface of the lens, the front surface to be exact.  Nothing to do with the cornea.  The pupil size is only relevent because it will determine the amount of rays that can enter at any one time, hence sph abe and coma.
> 
> At this point it really seems like you are more intent to be right than to discuss the facts and potential benefits (again I said potential).  I don't have the time to teach you optics and you don't seem to have the patience to read a book, so we are at an impasse.


Oh my god.

Yes we are really in impasse I can see.
This statement only make the Pupil size question even more unrealistic. Even Essilor agree on that according to the message above. I can go so far to agree, that you can make a special and better design in low light conditions only, but this has nothing to do with the pupil size. All new Freeform designs work better in low light conditions because of power and design compensating are getting better. -but again, nothing to do with the pupil size. It´s still a marketing gimmick.

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## Uilleann

I've never met Pete.  I've never had lunch with the guy.  I don't know his kids.  But he *seems* to be a pretty up and up guy.  I don't believe that he'd try to tell us that it was just some "marketing gimmick" - preferred in a blind test of actual progressive lens designs on actual presbyopic patients if there wasn't at least some truth to it.

Sure, I could be wrong, he could be the devil himself, and play a mean fiddle to boot...but in the end, I think his fiddle music would just be a cheap ploy to get me to buy better strings.  ;):shiner: :Cool: 

Thanks for the expansive info you've provided Pete - and more than that, thanks for keeping a cool and level head through all the mud here!  :cheers::cheers::cheers::cheers::cheers:

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## Mr.Powers

Who does the refraction in USA ? are optometrist Educated to do that or only Eye doctors ?



best regards

Peter

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## HarryChiling

> Oh my god.
> 
> Yes we are really in impasse I can see.
> This statement only make the Pupil size question even more unrealistic. Even Essilor agree on that according to the message above. I can go so far to agree, that you can make a special and better design in low light conditions only, but this has nothing to do with the pupil size. All new Freeform designs work better in low light conditions because of power and design compensating are getting better. -but again, nothing to do with the pupil size. It´s still a marketing gimmick.


Actually the pupil size is directly related to spherical aberration.

Jalie, M. _The principles of ophthalmic dispensing_. 2nd ed. London, ENG: The Association of British Dispensing Opticians; 1972.

----------


## YrahG

> Actually the pupil size is directly related to spherical aberration.
> 
> Jalie, M. _The principles of ophthalmic dispensing_. 2nd ed. London, ENG: The Association of British Dispensing Opticians; 1972.


Thank you but that was not necessary, this is a commonly known fact in lens design.  So to continue to respond to his statements is moot.

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## OCP

> Actually the pupil size is directly related to spherical aberration.
> 
> Jalie, M. _The principles of ophthalmic dispensing_. 2nd ed. London, ENG: The Association of British Dispensing Opticians; 1972.


This is actually what im talking about and im sure this is what essilor is talking about. I just dont Think a progressive lens Can solve this issue in All light conditions.

Mike

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## YrahG

> This is actually what im talking about and im sure this is what essilor is talking about. I just dont Think a progressive lens Can solve this issue in All light conditions.
> 
> Mike


If essilor sets the pupil size to the largest possible pupil size imaginable then yes they could correct this condition, but at what cost?  Aberrations are not independent, a change in one will cause a change in another.  I too question the effectiveness of the claims on the lens, I will give them the benefit of the doubt that they have corrected Sph. Ab. but was it necessary? And at what costs?  If the lens becomes more astigmatic as a consequence I don't think it would be worth it.  So in true fashion we are argueing over some claim that essilor makes about an aberration that has traditionally been ignored due to it's minimal effects.  So Yes yoru rightit is a marketing gimmic, but it's not a marketing gimmic because the didn't do anything it's a marketing gimmic because what they did may not be of any consequence.

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## Mr.Powers

Sure at the End of the day

Essilor makes great progressiv lenses !!! 

it just the way they sell it, that sometimes get a little flambuent :-)


best regards

Peter

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## Uilleann

...but then again...

Show me a company - *ANY* company - in optical who doesn't at times wax poetic about the virtues of their own lens/product when compared against another competitor.  Everyone does it.  But by the same token, you're hard pressed *NOT* to find a _very good_ lens/product by *ANY* of the same.  Find what you're comfortable with - what works for you!  And in the famous words of that pointy-eared feller: Live long and prosper!  :p;):cheers::cheers::cheers:

----------


## BMH

WOW! This thread has been interesting.

Thanks PeteH and YrahG!

----------


## Lee Prewitt

This has been very interesting to say the least.  Great job Pete! Congratulations on bettering your previous design too.  You guys are always tweaking.

I have a question and one that I don't have the answer or any real knowledge about.  Early in the thread you were talking about "design on the fly" and how you have a dedicated comm line.  Is this really just file transfer in "real time" vs. data file transfer in memory bank?  I don't know how many files Shamir or others provide to their FBS manufacturers. I sounds really cool to say "We have NSA supercomputers that calculate your Rx to the exact time of day, etc." vs other manufacturers that have already precalculated the known parameters for the range of Rx possibilities.  Please someone enlighten us all.

BTW, I am forwarding this thread to our sales team.  There is wonderful info here not only on FF but Essilor design philosphy too.  Others are always envious of the top dog and I am sure that I am no exception.  You do make good products.  I for one appreciate Pete's efforts to educate us all.

----------

