History & Tech Question

[dbracer]

I'm writing a bit of free lance stuff for the general public. Magazine stuff.

I'm looking for the following:

1. Some hx on how the recent detailed aberration science and analysis got started in the spectacle industry, especially PA's.

2. What companies initiated it? Was Physio the first commercially successful movement in that direction? Was there a specific individual who said, "...wait a minute. Why aren't we taking this stuff more seriously like some other industries?"

3. Why was the spectacle industry so slow in jumping to better science and production in these matters?

4. Some comparison of the production of the several of the top end free form producers of PA's...say maybe Zeiss, Verilux, Shamir, Hoya ...etc. What are the intricacies of the digital numeric design and porduction and the subtle differences therein.

Can anyone tell me where to look?

(this has also been posted under PA's)

dbracer

[Barry Santini]

I'm writing a bit of free lance stuff for the general public. Magazine stuff.

Try September issue, 2005, of Sky & Telescope magazine.

I'm looking for the following:

1. Some hx on how the recent detailed aberration science and analysis got started in the spectacle industry, especially PA's.

This technology came initially from astro-science, where they attempted deformable telescope mirrors in order to compensate for atmospheric refraction, aka, "seeing." It was then applied to refractrive surgery analysis and correction. Then, an attempt to optimize eyewear lenses with the knowledge known, but the limitations as applied to eyewear kept firmly in mind.

2. What companies initiated it? Was Physio the first commercially successful movement in that direction? Was there a specific individual who said, "...wait a minute. Why aren't we taking this stuff more seriously like some other industries?"

Two reasons: 1. Eyewear does not lend itself to obtaining the full benenfits because of the dynamic-movement of the eye and head and
2. Research has shown that monochromatic eye aberrations are not stable over time, i.e., vision is fluid because of lenticular and systemic changes.

3. Why was the spectacle industry so slow in jumping to better science and production in these matters?

See above: The benefits, at least at this stage of technological implementation, are not all that significant.

4. Some comparison of the production of the several of the top end free form producers of PA's...say maybe Zeiss, Verilux, Shamir, Hoya ...etc. What are the intricacies of the digital numeric design and porduction and the subtle differences therein.

All proprietary information. Read all their marketing materials, and you'll glean the general idea of what incremental improvements can be done.

Can anyone tell me where to look?
Try the manufactuer's websites.

(this has also been posted under PA's)

dbracer

Be careful: It almost appears by your questions that you're looking for information to back your tentative conclusion, rather than the other way around.

Canon and the Rochester Institue of Technology are leaders in researching the fundamentla scienc behind human eye HOAs and the implementaion of their correction
.

Hope this helps.

Barry

[chip anderson]

Of late we seem to be attempting to name designs and techniques as science or technology. Leuwenhoc, Gallileo, Priestly, Newton are science. A little different design or grind on a lens isn't science or even technology. Just a slightly modified product.

Chip

[dbracer]

(Barry) Be careful: It almost appears by your questions that you're looking for information to back your tentative conclusion, rather than the other way around.

(dbracer) It is a fact that I am using conclusions already assumed or proven. I’m not doing an experiment. I’m doing an article based on known facts and/or conclusions about the improvements in our industry. It is proper to write about the development of concepts and the evolution of science and technology. It is my purpose to get it right. Your information is helpful as a general background of knowledge before the fact. Even this exercise is giving me a better feel for what I should write. And, I thank you.

(Barry) Canon and the Rochester Institue of Technology are leaders in researching the fundamentla scienc behind human eye HOAs and the implementaion of their correction

(dbracer) Thank you this is good information.


Hope this helps.

Barry

You have been helpful, Barry. You’ve made me think and given me some good ideas.

Respectfully,
dbracer.


Responses to your comments



Originally Posted by dbracer
I'm writing a bit of free lance stuff for the general public. Magazine stuff.

(Barry) Try September issue, 2005, of Sky & Telescope magazine.
Thank you. Are you saying that this will give me information of recent changes, however subtle you view them, within the spectacle industry that is pertinent to a lay reader? I will review it, but remember this is being written to inform the lay public of our industry’s prowess.

Being published in a scientific journal is a piece of cake. Can do it almost at will provided if you use well founded science. Being published in a general publication like Time, Good Housekeeping, Mature Living or even Pediatrics for Parents is horse of a different color. Acceptances are on a whim, feeling, or what the editor had for lunch. Acceptances are more rare than honest politicians.

I'm looking for the following:

1. Some hx on how the recent detailed aberration science and analysis got started in the spectacle industry, especially PA's.

(Barry)his technology came initially from astro-science, where they attempted deformable telescope mirrors in order to compensate for atmospheric refraction, aka, "seeing." It was then applied to refractrive surgery analysis and correction. Then, an attempt to optimize eyewear lenses with the knowledge known, but the limitations as applied to eyewear kept firmly in mind.

(dbracer) Yes. I’m well aware that they were using aberration science back in the 1800’s, although Zernike polynomials are a relatively new science (1930’s).

I know those teaching me of the outcomes of refractive surgery, which I have to deal with daily, started discussing aberration reduction by computer numeric control (a monochromatic concept) back in the late 80’s and 90’s. But if I’m going to write something about such matters I like to review literature that actually discusses the changes: not what I glean from appearances and assumptions.

2. What companies initiated it? Was Physio the first commercially successful movement in that direction? Was there a specific individual who said, "...wait a minute. Why aren't we taking this stuff more seriously like some other industries?"

(Barry)Two reasons: 1. Eyewear does not lend itself to obtaining the full benenfits because of the dynamic-movement of the eye and head and
2. Research has shown that monochromatic eye aberrations are not stable over time, i.e., vision is fluid because of lenticular and systemic changes.

(dbracer) The applications of intra-ocular aberrations are limited as far as spectacles are concerned. No argument, refractive surgery not withstanding. Much of the intra-ocular stuff the mind adapts and prefers anyway, provided no changes are made, but the incident extra-ocular aberrations can be controlled with great precision and can make a significant improvement in patient satisfaction, adaptation, and vision performance. And personally there is a pretty big difference in my Shamir Autograph II Variable and my old AO progressives.

One of my jobs is to clean up after surgeons, and it’s a helluva lot easier now than back when the monochromatic adjustments were considered unworthy. Changes in any science are not done in great leaps. They are minor adjustments over time which most consider insignificant individually. The PA’s I wear today are nothing like the Univis I was “certified” in 30 years ago all because of minor little adjustments. Most were taken from monochromatic ray tracing science. Tedious stuff like Darryl Meister does. Ultimately it makes a difference.

And concerning “monochromatic” changes, lets not forget that much has been done that is not monochromatic. AR advances and Abbe values are not monochromatic. If you knew what passed for and AR coating back in’75 you’d be pretty amazed at what’s out there now. And maybe you do, but some of it deserves considerable appreciation.

3. Why was the spectacle industry so slow in jumping to better science and production in these matters?

(Barry) See above: The benefits, at least at this stage of technological implementation, are not all that significant.

(dbracer) “Not all that significant” from what? Are you saying there is little difference from a 1940 glass Tiller -6.00 to that same lens produced top-end today? Just in my professional life time labs have gone from sloppy dirty machines that ruffed and polished lenses, taking hours, to computer numeric controlled cutters that produce precision astigmatic, aspheric and PA designs and even more complexities to numerous to mention.

Back in the 90’s the refractive surgeons new they had to quit producing perfect “ball bearing” corneas and actually solve the disturbing vision they were creating. They were concerned, and rightfully so. Until some of these changes took place the spectacle industry was satisfied with status quo. Little had changed in the physics considered for lens production for several decades with deference to AR’s and material science.

I contend that until recent years the spectacle industry was a little lazy, and I was part of it and doing little.

4. Some comparison of the production of the several of the top end free form producers of PA's...say maybe Zeiss, Verilux, Shamir, Hoya ...etc. What are the intricacies of the digital numeric design and porduction and the subtle differences therein.

(Barry) All proprietary information. Read all their marketing materials, and you'll glean the general idea of what incremental improvements can be done.

(dbracer) Good point. I have reviewed these sites at length but few are willing to actually state the little differences “that make a difference” although incrementally small. For example I don’t think a free form Physio and a Shamir Autograph II are comparable if the intricacies of science are given due consideration. Certainly I can “glean” to some extent, but if I’m going to tell the public, I don’t want someone coming back and saying, “But you didn’t consider this…”


Can anyone tell me where to look?
(Barry) Try the manufactuer's websites.

(this has also been posted under PA's)

dbracer

[dbracer]

Of late we seem to be attempting to name designs and techniques as science or technology. Leuwenhoc, Gallileo, Priestly, Newton are science. A little different design or grind on a lens isn't science or even technology. Just a slightly modified product.

Chip

You are correct that as a writer I’ve made little effort to distinguish between science, technology, and production, and it is my duty to choose words correctly. But, I think you may be hairsplitting here.

The progress and alterations in process of designing a lens that removes distortion and improves human acceptance and function I believe could easily be called a technology. The very root of technology (Gr.1615) is one meaning systematic treatment. The modern definition is the study, development, and application of devices, machines, and techniques for manufacturing and productive processes.

Knowing that alterations in curvature on the back of a spectacle lens is usually better than on the front is a subtle difference but definitely in improvement in spectacle lens technology. The only way one could discover such mathematically complex changes are beneficial is through the study of the physical and natural world and phenomena by systematic observation and experimentation, which is the very definition of science.

Science (the study of the physical world) leads to changes in technology (science applied to practical application).

Thank you Chip. You have a point, and you made me think about terminology more critically.

Respectfully,
dbracer

[RT]

A little different design or grind on a lens isn't science or even technology. Just a slightly modified product.

I get it. It's cool to dismiss other parts of the ophthalmic lens industry as being mere smoke and mirrors. But I think that dbracer has a good grip on what constitutes technology. Your sweeping generalization, while you may think it's humorous, is actually offensive.

While you may be dismissive of the technology required to develop the latest generation of lenses, it is really there. Significant advancement was required in all of the following fields to make "FreeForm" or "Individualized" progressives possible (i.e. a slightly different grind on a lens), none of which have anything to do with what the design itself looks like:

• Computing technology for generating the complex tool paths required for full customization
• Computer Networking and Information Technology, for the simultaneous ability to disseminate the calculations while protecting the intellectual property of the developers of the designs
• Grinding/lathe technology to reproduce the designs
• Polishing technology
• Laser engraving technology, to mark the lenses
• Mesurement/verification technology to verify the accuracy of the lens produced

Since 1988, when Gerber introduced the first digital generator capable of surfacing custom toolpaths to .01 diopter resolution, it's taken about 20 years for all the other pieces of the puzzle to fit into place to get to where we're at now. And a big part of that is to do it at a price that the market can bear. Sure, we could have gotten a multi-million dollar Cray supercomputer in the late 80's to handle the necessary calculations. But clearly the price tag would have put that part of the process out of reach. Technology sometimes isn't just about the "Gee whiz" part of the science, but also in making it more affordable, more reproducable, more secure, or more reliable.

So yeah, there is plenty of technology involved in modern lens design and production. Perhaps more so than in other areas of the ophthalmic lens supply chain (refraction, fitting, dispensing, etc.).

As an aside, HOYA Corporation (my employer) also has been named to BusinessWeek's Tech Top 100 companies in the world. That would certainly qualify at least portions of the company as being related to science or technology, wouldn't you think?

[dbracer]

RT,

Thanks for addressing the great accomplishments of lens production. You’ve made just my point. But you've brought up a point I hadn't considered. I have not considered the "cost factor."

Can you help me with understanding production differences? Hoya is a good company. I’m uncertain as to the production comparisons.

I know that Shamir (they are very free with providing production information.), for example, uses front side base curves putting all SRx changes on the back of the lens through CNC.

The front BC is molded from glass molds which are also CNC fabricated. The molds are used until they become a reproduction liability, then replaced. Such constant front base curves and all back CNC designs are not necessarily the norm.

I know that ceramic molds are more common, and usually aren’t computer generated. Replacements are less frequent by some companies.

How does that compare to the way Hoya does it, addressing mainly PA’s.

Respectfully,
dbracer

[RT]

HOYA's traditional core competency involves using glass in many different industrial applications. For casting organic (plastic) PAL's, HOYA uses glass molds that are created off original ceramic masters. Each glass mold typically can cast fewer than 100 lenses before replacement (exact life depends upon lens material, wear, etc.). I'm not privvy to the details of the ceramic mold creation process, other than they are treated well--they are the expensive embodiment of a the intellectual property that makes up a lens design.

HOYA makes 3 types of PAL:

• Conventional front surface molded PAL, toric back surface (GP Wide, Summit ECP/Pro, Summit CD)
• HOYALUX ID, where both front and rear surface are surfaced in the Rx lab with complex curves to achieve a dual-surface customizable design.
• ID Lifestyle, which employs a front surface molded blank, combined with complex rear surfaces, to achieve a result similar to HOYALUX ID design. The front surface molded blank, however, differs significantly from conventional front-molded PAL's in that only the vertical elements of the progression are present. Thus, for example, the left and right lens fronts are identical--the horizontal elements that include inset are part of the complex rear surface.

Although using molds to cast front surfaces lacks the "sex factor" of freeform production, it is an inexpensive and highly reproducible way of getting the precise surface that the designer intended.

Note that the steel masters for injection-molding of polycarbonate PAL's, and masters for creating mineral (glass) PAL's use very different technology from those used for casting organic (plastic). I am less familiar with those methods.

Best regards,

[dbracer]

RT,
That is exactly the kind of information I've been looking for.

Thanks a bunch. Finally someone is willing to just state the facts. I appreciate your forthright sincere honesty.

So when a company uses the precision front molds, do they all use Hoya's theory of addressing magnification and distance issues on the front, and the power issues on the back? Or is that specific to Hoya?

Also, I can kind of understand the "magnification" concept being on the front, but I'm a little confused as to what the "distance" issues are??

Respectfully,
dbracer

[xiaowei]

Hi bracer

You are correct that as a writer I’ve made little effort to distinguish between science, technology, and production, and it is my duty to choose words correctly. But, I think you may be hairsplitting here.

IMHO, you also made too little effort to distinguish between science, technology, and MARKETING HYPE! Dont believe everything (or better believe only little) what official marketing and "white papers" tell you, especially in the spectacle industry it´s only backed up marginally by true science.

The progress and alterations in process of designing a lens that removes distortion and improves human acceptance and function I believe could easily be called a technology. The very root of technology (Gr.1615) is one meaning systematic treatment. The modern definition is the study, development, and application of devices, machines, and techniques for manufacturing and productive processes.

YOU CANNOT remove distortion from most spectacles, especially from PALs without really hampering the basic function. You can somehow move the distortion around that many people will not notice it.

To be more specific, the Minkwitz theorem still applies today and cannot be circumvented and all the "wavefront stuff" was already the basis for the works of Tscherning, the lenses like the "Punktal" glasses and so on. With today computers you can make the underlying calculations more accurately and WAY faster but the major aberrations like off-axis astigmatism power error and maybe coma were already known long ago, because they only require tracing very few "rays" through the lens.

With modern aspheric lens designs, you have quite a number of new "degrees of freedom", but if you read through a good book on theoretical spectacle optics as the one by Diepes and Blendowske (unfortunatelly only in german, as it seems) you learn that there is "no free lunch", almost all of the newer aspheric designs have some drawback that you need to pay for e.g. going to "thinner" lenses, either you minimize the cylinder error or the power error, but not both.

Knowing that alterations in curvature on the back of a spectacle lens is usually better than on the front is a subtle difference but definitely in improvement in spectacle lens technology. The only way one could discover such mathematically complex changes are beneficial is through the study of the physical and natural world and phenomena by systematic observation and experimentation, which is the very definition of science.

The difference between front and back surface treatment is another of those hypes and mostly stressed due to patent issues and the like. It´s a subtle difference AND a subtle improvement, if ever. For a spectacle lens, which is in most cases optically a "thin lens", even putting the very same surface topology on either side will make very little changes to the result (at least for reasonable prescriptions not waylarger than +/- 10 D or lense thicknesses in the order of only a few mm) With modern technology (here I agree with your point) you would also be able to calculate and to put a slightly modified design on the front instead of the back and get almost exactly the same result as for the back design. The common "keyhole" analogy is highly misleading, in a typical lock, the hole is WAY deeper (in the order of an inch) than the typical thickness of an eyeglass.

Thank you Chip. You have a point, and you made me think about terminology more critically.

Respectfully,
dbracer

I hope so, tooo!

Cheers:cheers: