Did you know this secrets:

[HarryChiling]

Hi Darryl

If you measure panto with the Infral, would the result be equivalent no matter how the patient a standing with their head?

The panto that is used to compensate the design is to me better thought of as the angle the lens makes with the visual axis, not the angle it makes with the plane perpendicular to the floor. So as the head moves so to does the eye's and glasses in a stationary group of objects. The angle compared to the plane perpendicualr to the floor will change, but the glasses will remain relatively stationary in front of the eyes

You say that opticians are more than capable to measure Panto and Vertex. This is conjecture as well. Everyone reading here, try to let different opticians in your stores take these measures. I will promise, that you will all get different results, and sometimes the result will be very long away from "reasonably accurate".

I think your point here is valid, I am not sure that most opticians are more than capable but a select few are and those are the ones that tend to visit this board so we are lulled into a sense of greater opticians out there as the norm. Manufacturers have taken this varying degree of education and skill into account though, the lenses can be ordered with vertex, panto, and faceform or not, the accurate measures optimize the design to the pateints particular situation. Without these measurements "averages" are used to create the lens. Every lens from the traditional molded designs to the freeform make assumptions that the lens will have a certain degree of tilt panto and faceform and they are designed for a certain vertex distance. Even single vision designs are designed for a certain vertex distance.

I do not know your skills in US, but in Denmark, where we have 4½ years of education, it´s a problem. I´m quite sure the same issues is seen in other countries.

Same issues here the measurements can be off from a little to a significant, the reason why more equipment and measureing tools keep coming out. These lenses are the creme of the crop, this is not conjecture but a majority of PAL non adapts coem from wrong measurements PDs and seg hgts. Throw in additional measures and you have a point that issues may coem up, but again keep in ind these lenses are not your average ordinary lenses.

If Panto and Vertex was fixed, the tools to measure these values should be good enough. You claim that they are not and we will se new and better tools. Why? A fixed value is very easy to measure.!

Although the angle the lens makes with the visual axis is fixed the angle the lens makes with the plane perpendicular to the ground is not fixed and this can and does cause error. While their is room to improve the measureing device education for the measurer is far more simple IMO. However, the march for improved measureing devices moves forward.

Everyone here: Please understand that this dialog is not because I´m stubborn (Darryl could just as well be that), but Darryl has a great reputation here and many consider Darryl as the great optical guru, as he certain are in many cases. For me, I look just more and more opinionated, and I know that. I´m alone in the wrong class where everyone agree with the "teacher", and not strong enough to just ignore this thread. Lucky me we are thousandth kilometre from each other, otherwise you would all beat me up in the schoolyard.:hammer:

Mike

I think when it comes to opinionated I will have to defend my throne, but you can be prince if that suits you. Darryl has opinions and you have opinions but when it coems to facts they are just that, facts. I would say Darryl is one of the great optical minds in our country and his ability to share the most complicated subject while trying to avoid bruising ego's is a real show of class.

Personally, I wouldn't beat you up until after we had a few pints. ;):cheers:

[Darryl Meister]

If you measure panto with the Infral, would the result be equivalent no matter how the patient a standing with their head?

Because the pantoscopic tilt angle is based upon the line of sight, which should pass through the fitting cross when the eye is in "primary position," deliberately tilting your head can influence the measurement. Patients should maintain their habitual posture during the measurement cycle in order to ensure optimum results.

You say that opticians are more than capable to measure Panto and Vertex. This is conjecture as well.

Yes, it is conjecture, which is why I preceded the statement with "I believe," instead of concluding the statement with "That's a fact" as you have done after several conjectures.

Everyone reading here, try to let different opticians in your stores take these measures. I will promise, that you will all get different results, and sometimes the result will be very long away from "reasonably accurate".

Possibly, but only because supplying this measurement represents a fairly new and possibly unfamiliar concept. But with the right tools and training, I am confident that eyecare professionals could take these measurements within a level of accuracy suitable for ordering customized lenses with an improved visual outcome.

Technology continues to evolve in every industry. In my opinion, most eyecare professionals would choose to enhance their skill sets to reflect advancements in clinical care and the current state of the art, given the opportunity.

Besides, you're not really arguing against taking these measurements, you're arguing against taking these measurements using anyone else's method but your own. After all, you seem to be happy to supply pantoscopic tilt angle using Shamir's (?) method of specifying either 5, 10, or 15 deg, which I've already demonstrated is no less prone to errors.

I do not know your skills in US, but in Denmark, where we have 4½ years of education, it´s a problem.

Are you suggesting that it takes professors in Denmark more than 4½ to teach opticians in Denmark how to measure pantoscopic tilt? Although I do not live in Denmark, I suspect that teaching this measurement simply isn't part of the curriculum at the moment.

If Panto and Vertex was fixed, the tools to measure these values should be good enough. You claim that they are not

No, I'm afraid that I didn't claim that.

You read me wrong. Vertex design compensating DO influence the vision area, but not the POWER in the vision area. Pow. compensation is only when you got the refracted Vertex as well. If the Vertex is very short, lets say 7 mm, then it´s acually possible to increase the vision area by increasing the CYL/SPH abberations in the peripheral zones...

I didn't really understand the point in this section. Possibly this is due to a language barrier.

It is difficult to influence vision without influencing power; in fact, it would require either a significant level of high-order aberrations or a media defect, such as scatter from surfacing aberrations. I doubt that you are referring to either though.

In any case, unless you have actually used progressive lens optical design software at some point that is capable of optical optimization for the position of wear, and then compared the results of different lens design scenarios, you may be overstating your knowledge of these effects on lens design.

Thats a fact.

I would feel considerably more comfortable discussing these matters with you if you were to refrain from referring to everything you say as a "fact." Unfortunately, many of your comments have been rather inaccurate, not factual.

Anyway it works great in the theory, because if the Vertex is not 7 mm in real life, but lets say 10 mm or even more, the increased Cyl. Abberations could actually make a worse design than the client are used to.

You have made several statements regarding "real life" performance, although these have all been based upon conjecture and your own anecdotal experience. The so-called "theoretical" arguments that I have provided are at least deductive arguments easily proven, regardless of whether the results will be significant enough for all wearers to experience a notable visual difference. Besides, there are already clinical studies available that do indeed detail the "real life" differences among actual wearers.

Darryl has a great reputation here and many consider Darryl as the great optical guru, as he certain are in many cases.

I would attribute any positive reputation I may have in this industry to a genuine desire to learn and share as much as possible with an open, objective mind. After all, we're all in this together.

For me, I look just more and more opinionated, and I know that. I´m alone in the wrong class where everyone agree with the "teacher", and not strong enough to just ignore this thread.

Mike, if everyone agrees with me, it is only because I have provided sound deductive arguments, numerical examples, contour plots, etcetera. You, on the other hand, have unfortunately relied primarily on anecdotal evidence, claims that lack any scientific basis, and fallacious arguments, even resorting at some points to ad hominem, red herrings, etcetera.

Lucky me we are thousandth kilometre from each other, otherwise you would all beat me up in the schoolyard

I think you will find that the vast majority of OptiBoarders are very open-minded and respectful of other members. Besides, we have members in most countries, so you really aren't safe either way. ;)

[Laurie]

Hello Again,

Darryl has an excellent reputation here, and in the optical community at large...I had the pleasure of meeting him years ago when he was still a very young Meister Rama! (sorry Darryl, I couldn't resist) ; )

Back to point:

Do these measurements matter? We have debated this for several pages, I would summize:

Since the learning curve is large to get everyone on board to feel comfortable talking to patients/clients and taking accurate additional measurements, it is best to use defaults until ready.

Those who are ready, go for it! As Barry has mentioned several times, he is getting fantastic results. As Darryl mentioned, the 'target' will be closer than it would with global defaults.

We are really splitting hairs here, tiny percentages of Diopter changes, however, I still believe that there are hyper-sensitive visual people who can tell the difference. I also still believe that the 1/8th Diopter ANSI tolerance is more about previous limitations in surfacing manufacture than the actual tolerance of our visual system.

: )

Laurie

[Barry Santini]

I also still believe that the 1/8th Diopter ANSI tolerance is more about previous limitations in surfacing manufacture than the actual tolerance of our visual system.

Laurie

Here, I would respectfully disagree. The only reasons why some feel that 1/8th D is too large a tolerance is that

THE RX YOU BEGIN WITH IS NOT OPTIMIZED FOR THAT CLIENT'S VISUAL EXPECTATIONS.

This is part of my ABOM paper. It's close to my heart.

In the end, ECPS are well advised to take those POW meaurements on EACH AND EVERY CLIENT, regardless of lenses being made.

All these "measurements" are, in reality, "contact points" between the patient and the ECP. If nothing else, they will convey to the client that something new & special is being done now.

Something no "online" fulfiller could ever hope to duplicate.

The wise amongst us will see my point.

Barry

[AWTECH]

Hello Again,

Darryl has an excellent reputation here, and in the optical community at large...I had the pleasure of meeting him years ago when he was still a very young Meister Rama! (sorry Darryl, I couldn't resist) ; )

Back to point:

Do these measurements matter? We have debated this for several pages, I would summize:

Since the learning curve is large to get everyone on board to feel comfortable talking to patients/clients and taking accurate additional measurements, it is best to use defaults until ready.

Those who are ready, go for it! As Barry has mentioned several times, he is getting fantastic results. As Darryl mentioned, the 'target' will be closer than it would with global defaults.

We are really splitting hairs here, tiny percentages of Diopter changes, however, I still believe that there are hyper-sensitive visual people who can tell the difference. I also still believe that the 1/8th Diopter ANSI tolerance is more about previous limitations in surfacing manufacture than the actual tolerance of our visual system.

: )

Laurie

I agree with this as those who have a single store and a strong well trained optician can really make sure the staff is trained and up to speed. A 6 office group on the other had will probably not have the dedicated training staff to oversee this to make sure accurate measurements are actually taken by all.

The other factor in the difference between actual correct individualized patient measurements and estimates is the accuracy of the prescription.

[Barry Santini]

I agree with this as those who have a single store and a strong well trained optician can really make sure the staff is trained and up to speed. A 6 office group on the other had will probably not have the dedicated training staff to oversee this to make sure accurate measurements are actually taken by all.

This then, is my main bone with the schools and the state of opticianry skill/education today.

2 years is not enough. Certainly not enough to expose the students to what they need to know.

And definitely not enough to ensure competant mastery of the necessary skills to be a qualified and certified ophthalmic dispenser.

Barry

[AWTECH]

This then, is my main bone with the schools and the state of opticianry skill/education today.

2 years is not enough. Certainly not enough to expose the students to what they need to know.

And definitely not enough to ensure competant mastery of the necessary skills to be a qualified and certified ophthalmic dispenser.

Barry

This is a challenge for suppliers such as my company. One state has strong state requirements and others .... Well the optician my have had a job yesterday where they had to know, "would you like fries with that?"

[Uilleann]

I believe that if each of us were to take a random sampling of our state, or even our local area - to include ALL types of dispensaries and optical practices, private, and big box etc...that we would be frightened to learn of the ability or perhaps the INability of our profession as a whole to get so much as a reliable seg ht. or accurate mono pd on a patient.

It's often pointed out that most of the populous of Optiboard are not your garden variety optician/dispenser. Rather most here are in the upper most percentile of their trade. And yet even here, we can't agree on what makes good sense in regards to POW measurements and lens optimization. I think there's a good chance we'll get there, but as Barry is quick to point out, it will require much more stringent educational and practical training requirements to be put into effect industry-wide.

As things stand now, I don't see that as a realistic eventuality in the near future. If only Arthur C. Clarke had gotten it right and made 2010 about the state of opticianry and not about big Jovian monoliths...we might be some where. Time to find my monkey suit...now where's my bone to toss in the air?! ;)

[Barry Santini]

...we would be frightened to learn of the ability or perhaps the INability of our profession as a whole to get so much as a reliable seg ht. or accurate mono pd on a patient.;)

I realy think that words like accurate or reliable are inappropriate for the skills of obtaining measurements.

I prefer "appropriate". For instance, taking a pupil height for any type of ;lens should be relatively reasy tpo master.

Knowing what to do with the pupil height, i.e., compensating the height based upon posture, fit or intented use is *really* the skill.

My 2 cents

Barry

[Uilleann]

I realy think that words like accurate or reliable are inappropriate for the skills of obtaining measurements.

I prefer "appropriate". For instance, taking a pupil height for any type of ;lens should be relatively reasy tpo master.

Knowing what to do with the pupil height, i.e., compensating the height based upon posture, fit or intented use is *really* the skill.

My 2 cents

Barry

*Cleaning coffee from my screen* I thought for a second there Barry, that you'd reverted into Scooby Doo speak there. hehehe A good laugh, when my brain ain't yet firing on all cylinders yet this morning! :bbg:

I get what you're saying here, though I'd still likely use my original jargon. My point being that there are still far far too many remakes I'm aware of for things like a bad seg or pd, and that adding the complexity of POW measurements would almost certainly compound that given our current state of "training" in the industry as a whole.

Again, the simple fact that we're even here, discussing POW and it's implications, sets us apart from the vast and wide majority. Something I'd love to see change. Then again...wouldn't we all right?

Cheers my friend! :cheers::cheers::cheers:

[Barry Santini]

Typiong wilh neber ve ny forte.

B

[qsquaretoo]

I guess the design optimization can tolerate the daily wearing position change in real life. So Mike's way of using "pre-set" values works. Otherwise, wearing an individualized PAL is not a man's job :)

BTW, I read US6,089,713 and it does not teach how the parameters of wearing position are used in design optimization :), except mentioning.

-QQ

[Optoanomalicious]

Hey Mike,

Let me have a comment with regards to your little secrets. When you start using free form lenses and the lens manufacturers ask you to measure VD, PT, and BC, these datas are relevant in order to maximise the lens' comfort for the wearer. Now it comes down to the personnel's skill in taking these measurements whether they could be as accurate or not. Also it depends on the quality of the lens, that's why you need to choose your lens carefully. One is more superior than the other in terms of design. My shop dispense mostly high index rodenstock impression and believe me, they are different.. When these datas are measured correctly and your optician is highly trained to fit the specs, That's when we're talking about price differences between Essilor Physio 360 and Rodenstock Impression. In terms of comfort, only the individual could tell when they have it on for as long as they feel wearing them. When you know how to do it correctly, then it should produce the optimum result my friend. Hope this helps