Did you know this secrets:

[Darryl Meister]

Does an optimized surface of a lens work when it is mounted 0.5mm wrong by the lab? (I know it shouldn't be, but again real world) etc., etc., etc

I've never really understood the merits of this argument, which seems akin to OCP's argument. Optically customized lenses seek to preserve the intended optical performance of the lens design, regardless of the prescription and/or position of wear.

Consider your own scenario: A frame initially fits the patient with 12 degrees of pantoscopic tilt. You measure it at 10 degrees of panto. Your patient puts the frame on the next day, higher on the bridge of the nose, so it is now at 9 degrees of panto. Does this mean that the lens suddenly stops working compared to a lens that is not optimized for the position of wear at all? Of course not. You are still 9 degrees closer to providing the intended optical performance than you would have been.

That said, I want to reiterate the fact that I completely agree that free-form lens suppliers only compensating the prescription for the position of wear, and not modifying the actual lens design, are not delivering meaningful visual improvements any many prescriptions, simply because the optical differences involved are indeed quite small.

[OCP]

delete

[Darryl Meister]

You show two plots with +3 D in two different vertex distance and with different design. BUT you did not told us the refracted vertex on the first plot.? If the refracted vertex for both designs is 7,5 mm, the plot will natural be different, because the power comp. would make the shorter vertex with stronger power.!

1. All three lenses in the comparison use the exact same lens design.

2. All three lenses were calculated to provide a +3.00 D at the specified vertex distance, so there is no difference in power between the refracted and fitted vertex distance.

3. Yes, the lenses look different anyway, as I have been saying all along. ;)

[OCP]

1. All three lenses in the comparison use the exact same lens design.

2. All three lenses were calculated to provide a +3.00 D at the specified vertex distance, so there is no difference in power between the refracted and fitted vertex distance.

3. Yes, the lenses look different anyway, as I have been saying all along. ;)

Hi Daryl.

Okay back to my statement that Vertex is more theoretical than optical noticeable improvement, and still most opticians cant measure both vertex values correct. Anyway. Does you have an power plot?

Annoying Mike

[Mr. Finney]

This is because this tilt is very difficult to measure and because it´s not an fixed measure. It depends on how the person is standing, and therefore I suggest you measure this value visuel. Of cause you cant measure 100% correct this way, but you cant measure this value 100% correct anyway, so it´s an question of ordering realistics as possible.

Just FYI, my glasses have the same panto angle whether I'm sitting, standing, lying down, watching TV, taking a shower, etc.

About the Vertex you need to announce the refracted vertex AND the fitted vertex, because it´s the difference between these two values that makes the pow. comp. BUT it only makes a difference if the power is above 5D and it will only give optical improvement if you measure both values 100% correct, and that is nearly impossible.

That's actually quite a ridiculous statement to make. So if I measure both values only 98% correct, there won't be ANY optical improvement? Wouldn't the improvement depend on how far from the mean values my measurements were, assuming my measurements were closer to perfect than the mean?

If your power is -6D and you measure 2 mm wrong, the lenses will NOT work. It´s very easy to measure 2 mm wrong in difference.

So a power of -6D will work, but a power of -5.93D or -6.07D won't work? Because that's the diference you're talking about. Which points out that both viewpoints are correct. Vertex power compensation doesn't make that big of a difference, but why shouldn't we attempt to get things as close to perfect as we can?

The Vertex distance does not change power so much. You can see the difference when you put an client from -3 glasses to contakt lenses. How much does the power change? Maximum 0,25 D in 13 mm difference!!!
The difference between the refracted Vertex and the Fitted Vertex lets say this is only 2 mm. How much would the power change then? I tell you. Aprox. 0,04 D !!! So the Vertex value is in the most cases an theoretical improvement.!!

So what you're saying, just as Darryl and others have said, is that power compensation, not design compensation, for vertex distance, is not a big factor. Right? We all get that.

[Barry Santini]

You know, I actually consulted our great DM on this whole question of panto. And I think Laurie S also chimed in before and helped to cleared it up:

You appropriately measure pantoscopic tilt by first ensuring the the client's "facial plane"., i.e. head plane (Try drawing a line across the upper and lower orbital bones, and further iterate with the dental plane of the mouth and the chin) is as straight up & down as possible.

(I think someone in Texas, in the 1970's made a series of "proscopic heads" to help train dispeners how to fit and measure eyewear).

WITH THE CLIENT'S HEAD IN THIS "ORTHOGONAL" POSITION, USE THE ZEISS PANTO PLUMB (OR SIMILAR DEVICE) AND ASCERTAIN THE TILT OF THE ALREADY PRE-FITTED EYEWEAR.

It's doesn't matter after that if they habitually tilt their head forward or backward (except with respect to pupil height position).

This then, is the pantoscopic angle the designers are looking for in order to perform their optimizations.

And I'm still open to being further corrected here.

Barry

[Darryl Meister]

Yes, as long as you have measured the pantoscopic angle of the frame with the line of sight passing through the intended fitting point on the lens, head tilt no longer matters, at least as long as you have measured the fitting height correctly.

[AWTECH]

You know, I actually consulted our great DM on this whole question of panto. And I think Laurie S also chimed in before and helped to cleared it up:

You appropriately measure pantoscopic tilt by first ensuring the the client's "facial plane"., i.e. head plane (Try drawing a line across the upper and lower orbital bones, and further iterate with the dental plane of the mouth and the chin) is as straight up & down as possible.

(I think someone in Texas, in the 1970's made a series of "proscopic heads" to help train dispeners how to fit and measure eyewear).

WITH THE CLIENT'S HEAD IN THIS "ORTHOGONAL" POSITION, USE THE ZEISS PANTO PLUMB (OR SIMILAR DEVICE) AND ASCERTAIN THE TILT OF THE ALREADY PRE-FITTED EYEWEAR.

It's doesn't matter after that if they habitually tilt their head forward or backward (except with respect to pupil height position).

This then, is the pantoscopic angle the designers are looking for in order to perform their optimizations.

And I'm still open to being further corrected here.

Barry

I agree with you this is a proper way to measure panto, but my concern is limited number of opticians that know how to do this. Some will just not get it, remember supplying lenses we are dealing with a very few knowledgable opticians and also alot of people selling lenses who the day before they were an optician there business lingo was, "would you like fries with that order". In many cases as was originally stated the method suggested may produce a more satisfied patient than a poorly trained and educated craftsman with an excellent tool.

I will even go so far as to say Barry you could probably take a known frame fitted to an unseen patient, (Thats right one you have never even met or seen a picture of), and supply a better estimated panto than a poorly trained dispenser with a fancy panto tool.

I have expressed my concerns before and suggested the best approach maybe to only offer such customized fitting by approved and trained opticians. (This idea will fair when discussed with the Sr. VP of sales)

[Mr. Finney]

I agree with you this is a proper way to measure panto, but my concern is limited number of opticians that know how to do this. Some will just not get it, remember supplying lenses we are dealing with a very few knowledgable opticians and also alot of people selling lenses who the day before they were an optician there business lingo was, "would you like fries with that order". In many cases as was originally stated the method suggested may produce a more satisfied patient than a poorly trained and educated craftsman with an excellent tool.

I will even go so far as to say Barry you could probably take a known frame fitted to an unseen patient, (Thats right one you have never even met or seen a picture of), and supply a better estimated panto than a poorly trained dispenser with a fancy panto tool.

I have expressed my concerns before and suggested the best approach maybe to only offer such customized fitting by approved and trained opticians. (This idea will fair when discussed with the Sr. VP of sales)

We could always let the so-called "opticians" poorly dispense lenses, then the customers will go to actual Opticians, who will dispense lenses that the customers can actually see well with, and the actual Opticians will thrive!:D:D

[Uilleann]

No.

They won't.

The "customers" will continue to "shop" based on price alone. And will think they're the shizzle because they "outsmarted" the "system" and got their plastic lenses and junk frames (BOTH pair mind you) along with their "free" eye exam for $60 bucks.

Way to go Joe Q. Public! :hammer::hammer::hammer:

[Pete Hanlin]

Barry,

You are correct regarding assessment of pantoscopic tilt (this seems to be one of the more challenging measurements for customizing lenses to fit- personally, I believe this measurement will have to be automated if we are to acheive an acceptable level of accuracy).

Regarding vertex, I can't help but think most of the posters on this thread are missing Darryl's point. If you are compensating for POWER, then yes- a couple mm one way or the other are of no consequence. However, you can adapt the DESIGN to vertex distance (as well as panto and face wrap).

Regarding the impact of customization to lens position, while I don't believe customization (of any kind) is going to make a bad design function well, I do believe the performance of a good design can be improved somewhat through customization to lens position.

[OCP]

I agree with you this is a proper way to measure panto, but my concern is limited number of opticians that know how to do this. Some will just not get it, remember supplying lenses we are dealing with a very few knowledgable opticians and also alot of people selling lenses who the day before they were an optician there business lingo was, "would you like fries with that order". In many cases as was originally stated the method suggested may produce a more satisfied patient than a poorly trained and educated craftsman with an excellent tool.

I will even go so far as to say Barry you could probably take a known frame fitted to an unseen patient, (Thats right one you have never even met or seen a picture of), and supply a better estimated panto than a poorly trained dispenser with a fancy panto tool.

I have expressed my concerns before and suggested the best approach maybe to only offer such customized fitting by approved and trained opticians. (This idea will fair when discussed with the Sr. VP of sales)

This is exactly what I meen. If the panto is measured perfect by all opticians everytime, it would be great, but if it´s VERY wrong it can be the reason the client cant see prober with the lenses, and then WE (the suppliers) got the problem. The same with the Vertex. If both values is measured perfect, like mono PD, FH and refracted power should be, then we would all deliver "first time" solutions every time. BUT in real life it´s another history, and with exactly Panto and Vertex we see more THEORETICAL improvements than we actually see optical noticeable improvements. The risk of doing something wrong is larger than taking the correct measures, AND therefore it could be better to make these two measures a little bit more standard in your clinics.

Vertex and Panto is NOT fixed values. So many exceptions. How do you measure the fitted Vertex? With a frame with plano lens? And how do you mount a +5D in a frame? With the groove to the front or in the middle, and does this influence the Vertex? It´s actually ridicullous to say 13½ mm vertex is better than 12 or 15.! The glasses in +5 is changing position on the nose all day as well.
Panto is NOT a fixed measure. It´s an measure that taking into account your head position when you looking forward, and in that perspective, the eyesight angle. It will never change of cause, but the lens design will be made from the Panto Tilt you measue in your clinic, and the client must put up with a bad design (if you measure wrong) for the next 2-3 years.

Front curve is the only fixed measure that dont change value, however you stay or lay down, jumping or swimming.

For Darrryl (I always read your post and highly respect these, even though they are very technical). I actually dont see much difference in your plot 1 and 3 with 7 mm difference in Vertex. Plot 3 looks actually like a plot from an inaccurate freeform lens, and could just as well be that. Three same FF lenses will all have slightly different plots because of inaccuracy from the FF generator. Lucky for us it don´t give problems in real life, because our eyes, or more our brains, are fantastic to compensate for these small errors. Thats the same reason I think these small theoretical improvements you can make by calculation the vertex and the Panto angle is more or less useless.

For Mr. Finney. Please read all the post before you call my statements ridiculous. I have just like Darryl been analyzed progressive lenses for more than 15 years, but more in a practical view than in a technical view. I can´t take your post serious.

I still hope that this dialog can open up some of the complications we have with this new technology. No doubt that all new FF individual lenses (included the Auto II) works a lot better than conventional lenses, but it would be better, in my opinion, if Shamir, Zeiss, Rodenstock and Essilor, would handle these two measure different, to make it more easy and safe to sell these products. I would guarantee it would change the succes rate to "first time succes" every time.

Still the annoying Mike

[OCP]

Barry,

You are correct regarding assessment of pantoscopic tilt (this seems to be one of the more challenging measurements for customizing lenses to fit- personally, I believe this measurement will have to be automated if we are to acheive an acceptable level of accuracy).

Exactly. :cheers:

Finally we are reaching some understanding.

[Darryl Meister]

I actually dont see much difference in your plot 1 and 3 with 7 mm difference in Vertex.

The third plot has nearly 1.00 D more unwanted peripheral astigmatism compared to the first plot as well as 0.50 D of unwanted astigmatism over the entire near zone.

Plot 3 looks actually like a plot from an inaccurate freeform lens, and could just as well be that. Three same FF lenses will all have slightly different plots because of inaccuracy from the FF generator. Lucky for us it don´t give problems in real life, because our eyes, or more our brains, are fantastic to compensate for these small errors.

I agree that a free-form surfacing process with poor process engineering and inadequate quality control can deliver poorer quality lenses compared to traditional semi-finished lenses. However, if you are seeing 1.00 D of unwanted astigmatism in your free-form lenses, that is pretty significant, even for "bad" free-form surfacing.

Yes, the human eye can tolerate small errors. Still, even small errors can degrade visual acuity and contrast sensitivity. For that matter, many individuals may or may not notice a significant difference in picture quality between DVD and Blu-Ray, but there are certainly a lot of consumers out there who want the best picture quality available.

In any event, I guess as long as you aren't charging more for free-form lenses that offer no additional forms of optical customization, however small the benefits of that customization to the wearer may be in your opinion, it really doesn't matter. However, most free-form lenses are positioned at "premium" price points, so what are these lenses offering to the wearer to command this higher price tag?

[Uilleann]

...For that matter, many individuals may or may not notice a significant difference in picture quality between DVD and Blu-Ray...

Wow. Seriously? They clearly need a current eye exam then, and some new specs. Send them MY way! ;) How can you NOT see the difference between the two?!?! It's rather huge-ish. :p:D

[Fezz]

Wow. Seriously? They clearly need a current eye exam then, and some new specs. Send them MY way! ;) How can you NOT see the difference between the two?!?! It's rather huge-ish. :p:D

He forgot to say:

"When viewed through polycarbonate lens material,............."


:cheers::cheers::cheers:;)

[Uilleann]

Oh Snap! :p:p:p:cheers::cheers::cheers:

P.S. Did you see my self-autographed PD stick? You promised me - and then fell through, so I had to....er....improvise!

http://www.optiboard.com/forums/show...402#post323402

[YrahG]

This thread brings up some very interesting points.

1. Opticians are not well equipped or knowledgble enough at this point to handle certain measurements required to fit these new individualized designs.
2. Some labs would rather keep breakages low using older techniques than educate their customers on how to utilize the newest technology.
3. Some labs have poor QC standards and little understanding of what they are making.

Again I must reiterate I find the most important aspect to provideing a quality FF design encompasses all areas of our trade, the design must be solid, the lab making the design must understand at least the basics of what they are providing, the opticians needs to supply said lab with fairly accurate data, the said lab needs to have stringent Q standards in pace.

I for one would be thoroughly ****** if my lab decided they were going to take away my ability to provide accuracy by giving me a 5, 9, 12 tilt measure instead of allowing me to accurately provide what the software vendor built in. I would drop this lab like a bad habit. Don't get me wrong I understand the reasoning behind such a procedure, but I am not the average optician and will not tolerate a lab enforcing me to be that. This may sound harsh, but let the labs stay in their place. I provide the data you create based on MY DATA.

[OCP]

This thread brings up some very interesting points.

1. Opticians are not well equipped or knowledgble enough at this point to handle certain measurements required to fit these new individualized designs.
2. Some labs would rather keep breakages low using older techniques than educate their customers on how to utilize the newest technology.
3. Some labs have poor QC standards and little understanding of what they are making.

Again I must reiterate I find the most important aspect to provideing a quality FF design encompasses all areas of our trade, the design must be solid, the lab making the design must understand at least the basics of what they are providing, the opticians needs to supply said lab with fairly accurate data, the said lab needs to have stringent Q standards in pace.

I for one would be thoroughly ****** if my lab decided they were going to take away my ability to provide accuracy by giving me a 5, 9, 12 tilt measure instead of allowing me to accurately provide what the software vendor built in. I would drop this lab like a bad habit. Don't get me wrong I understand the reasoning behind such a procedure, but I am not the average optician and will not tolerate a lab enforcing me to be that. This may sound harsh, but let the labs stay in their place. I provide the data you create based on MY DATA.

Many would prefer the same as you. No doubt. The three different tilt, call it A, B & C was only a solution to awoid wrong orders. Lets say you visuel could see that the tilt was very oblique, so you order C (12 degrees) but you was actually measuring 15 or 10 degrees. This 3 degrees difference will not spoile the lens design at all.! But if you by mistake was measuring 5 degrees (and that is easy) then you could have adaption issues. So by doing this value a little more standard you can avoid many non adapts or adaption issues.

Mike

[YrahG]

Many would prefer the same as you. No doubt. The three different tilt, call it A, B & C was only a solution to awoid wrong orders. Lets say you visuel could see that the tilt was very oblique, so you order C (12 degrees) but you was actually measuring 15 or 10 degrees. This 3 degrees difference will not spoile the lens design at all.! But if you by mistake was measuring 5 degrees (and that is easy) then you could have adaption issues. So by doing this value a little more standard you can avoid many non adapts or adaption issues.

Mike

So your saying I can visually determine 5, 9, and 12 but I don't have the capacity to verify visually whether I got a measure of 5, 9, or 12. This makes no sense, I could just as easily verify my measured results using a visual method, carpenters have a saying that would apply very well here, "measure twice cut once". As a lab if you are seeing this as an issue you need to isolate the offices that are having consistent issues and send your reps out to educate them onn proper fitting techniques and if thisdoesn't work change your remake policy or prices to ensure that it does not effect your bottom line. If I could use an analogy your suggest putting training wheels on a harley.

[OCP]

So your saying I can visually determine 5, 9, and 12 but I don't have the capacity to verify visually whether I got a measure of 5, 9, or 12. This makes no sense, I could just as easily verify my measured results using a visual method, carpenters have a saying that would apply very well here, "measure twice cut once". As a lab if you are seeing this as an issue you need to isolate the offices that are having consistent issues and send your reps out to educate them onn proper fitting techniques and if thisdoesn't work change your remake policy or prices to ensure that it does not effect your bottom line. If I could use an analogy your suggest putting training wheels on a harley.

The issue is not what YOU are able to do right. I´m sure you are doing a great job. The problem is more or less that the opticians are ordering a value that they dont have tools to do good enough, and they blindly trust the result from this tool. The problem is not here in Denmark alone, but all around the world you will see this is a problem.
You are so right about more education, but this is not so easy as it sounds.
It´s even better to make the ordering of the lenses a tad more easy, and it does not help when the manufacturer needs values like the Vertex and Panto that at the same time does not count so much anyway.

[Fezz]

The problem is more or less that the opticians are ordering a value that they dont have tools to do good enough, and they blindly trust the result from this tool.

Are such tools available?
Where?

[OCP]

Are such tools available?
Where?

Everyone has these tools. Shamir, Zeiss etc, etc.

[Fezz]

Everyone has these tools. Shamir, Zeiss etc, etc.

Maybe in your global location, but not in mine!

I am waiting for Shamir's tool to hit the states so I can get my hands on one! Maybe you could hook me up with two or three of them?

I have an Essilor one that was giving to me by a good friend who had to get them from his contacts in Europe!

I hate to say it, but these tools are NOT widely available, at least not in the USA.

[YrahG]

The issue is not what YOU are able to do right. I´m sure you are doing a great job. The problem is more or less that the opticians are ordering a value that they dont have tools to do good enough, and they blindly trust the result from this tool. The problem is not here in Denmark alone, but all around the world you will see this is a problem.
You are so right about more education, but this is not so easy as it sounds.
It´s even better to make the ordering of the lenses a tad more easy, and it does not help when the manufacturer needs values like the Vertex and Panto that at the same time does not count so much anyway.

It is not mandatory to supply those values, if you felt that your method of ABC lens design would work why not just implement it, send out a memo to all your accounts that in the future all orders will require A, B, or C values for tilt and then define what they mean. I don't think you'll see a huge change in the remakes honestly you might actually see an increase because you are adding a level of ambiguity to your ordering system. I would personally not use your lab and I know of many other offices that are just getting used to the whole tilt and compensation thing to try and throw a A, B, C into the mix.

Or if new technology is that much of a pain just throw in the towel and sell only traditionaly surfaced lenses.