Progressives?

[Jim Stone]

Pretty much, put them all in a bag, shake em up. What falls out is as good as what is left in the bag.

[Jim Stone]

Any arguments here? Come on. Why NOT??? Tell me why?

[For-Life]

Yes and no

I argue that if you match a Panamic, Gradal Top, Sola One, and Nikon i there is little difference.

But between a Super No Line and a Ipseo there is.

[Chris Ryser]

Any arguments here? Come on. Why NOT??? Tell me why?

Basically they are all the same................with some small differences which every manufacturer claims that they beat the competition..

They become pretty miserable reading instruments when used in the small narrow frames.

They are good and perfect for women and sometimes men who do not want to admit their age............who then will suffer by having a very narrow reading area.

They are all way overpriced as the manufacturing of them does not cost a penny more than to cast and make a regular bifocal. However this pays well to support the advertising hype towards the public who then wants more of them.

[Jim Stone]

Can there be verbal descriptions of the different lenses? I'd like to see people that know the differences describe them.

[For-Life]

Can there be verbal descriptions of the different lenses? I'd like to see people that know the differences describe them.

The descriptions are posted on OB on a daily basis. Do a search on Panamic, Sola Max, Sheedy report, Hoya CD, Ellipse and so forth and you will find them.

[Joann Raytar]

I agree with For Life. Hard designs and softer designs, longer and shorter drops to the add powers - brand to brand there may not always be a big difference but category to category there are.

[Chris Ryser]

Can there be verbal descriptions of the different lenses? I'd like to see people that know the differences describe them.

I just love that one.............................

And before you do hold the lenses in front of a projector lens, projecting a grid and also describe what you see on the screen.

[Jim Stone]

So I guess we'd have to have three or four bags?? Short fit, standard fit and computer or office lenses? Any more?

[hcjilson]

Don't forget dual surface technology....Definity and Physio 360!

[jameselex]

I go with pal for lots of reading, pal for lots of computer , ( of course, I assume they are all good for distance, I know some are not as good as others)that's all, I don't know I am lucky or what, didn't have many non-adapt.

free form? this and that, maybe i like to pay more for a pair of the same VIP but processed by FREE FORM TECHNOLOGY! and physio is the best, don't think so? Essilor told me.

[Darryl Meister]

They are all way overpriced as the manufacturing of them does not cost a penny more than to cast and make a regular bifocal.

Chris, while one could argue that it costs the same amount to poor resin into either a progressive mold or a bifocal mold, you've seem to have forgotten about everything else involved in the process of developing, validating, manufacturing, and distributing progressive lenses.

[Chris Ryser]

..........you've seem to have forgotten about everything else involved in the process of developing, validating, manufacturing, and distributing progressive lenses.

Darryl, I did not forget, but every other lens also needs the same qualifications you mention, which puts your argument back to ground zero.

The only other reason could be the advertising factor which is very costly but seemingly also very effectivily influencing the consumer, and the opticians love to sell expensive lenses that do not require a big selling job.

[Darryl Meister]

Darryl, I did not forget, but every other lens also needs the same qualifications you mention, which puts your argument back to ground zero.

Chris, I suspect that you have never actually designed a progressive lens series. Or even a traditional bifocal. ;)

I could go through all of the steps involved in both, but it would take awhile, so I'll have to revisit this thread later.

[Chris Ryser]

Chris, I suspect that you have never actually designed a progressive lens series. Or even a traditional bifocal.

Daryll, your suspicions are right, I never did............neither one,

However this feat is much simplified today with the presence of computers compared to calculate curves for AO Tyllier or Zeiss Punktal curves in the 1930's.

[Darryl Meister]

Tillyer and Punktal lenses used spherical curves, which didn't require any calculations (the formula for a sphere is very simple). However, Edgar Tillyer and Moritz von Rohr had to do trigonometric ray tracing to measure the amount of aberrations present across the lens for different spherical curves (actually, assistants generally did much of the numerical analysis before the advent of computers). And, if you recall, those lenses cost several times more than the standard lenses available at the time, which were also spheres.

[nickrock]

In response to Chris' and Darryl's discussion about cost of PALs vs. flat-tops, I always assumed the difference in cost was in the engineering of the actual progressive design as well as market research on how well it performs. I think we all know how a standard bifocal performs. My opinion is that we should all know that standard bifocals will always be what they are now and progressive lens technology will only get better and better over the years.

Anyway...these are some of my favorites:
*Standard PAL's for everyday use i.e. fitting height of 20 or higher: Gradal Top, tried and true (interested in newGT2), Vx Panamic, minimum fitting height of 18 published by Varilux is the biggest corporate lie to sell lenses ever. Anytime I've had a patient in a Panamic at 18, they always tell mehow the reading portion is so small or hard to find. Above 20= no problem
*Standard PAL's for Primary need of reading and/or intermediate: SolaMAX, again tried and true, never have had a non-adapt with SolaMax.
HOYA GP Wide, ok but certainly not as successful as the MAX. Skeptical PAL users coming from flat-tops do like the Liberty. Sorry to say it, but it works.
*Short Corridor PALs Catergory1 i.e. fitting height of 17-18. Not exactly a True short corridor, for for those fitting heights posted above that have been crammed in to a Panamic or some other crap that some optician was to lazy to actually think about and put on a layout chart. #1 Zeiss Brevity. I know minimum says 15 or something like that, but I found that the Brevity functions better at 17 minimum. Regular Physio fits into this catergory in my book. I have dispensed about 12 or so with a good response. We'll see over time. I'm new to using SOLAOne, but its been ok so far, I don't know much about it. Image is ok, too. Lots of material options.
*Short Corridor PALs Catergory2 i.e. fitting height of 14-17. A true short corridor/compact design for all those fashion-foward frames. I work in a high end shop and at least 50% of our patients fit into this catergory. Varilux Ellipse IS the best, and I'm not a Varilux ***** by any means. Now, in my experience with this lens it does not solve presbyopic problems for everyone. Meaning use good judgement with this lens. Not good for advanced presbyopes of +2.50 adds or higher. Don't put a patient that spends 8 hours a day on a computer in this lens. Common sense stuff people. I don't mind the Summit CD either. AO Compact would be my third choice as an inexpensive option. ---Again,these are just my picks. Let me know what you think. For the most part, these lenses are considered Premium Progressives. (TO me anyway.)

[SkiBunny]

Hi all... same old arguments here as last year LOL :D

[Chris Ryser]

And, if you recall, those lenses cost several times more than the standard lenses available at the time, which were also spheres.

During my times as a lab owner I used mainly Tyllier lenses until I found out that American Optical sold a cheaper brand lenses called "Amoptic" which turned out to be the exact same Tyllier lenses under a different name packaged in a differet envelope.

Explanation by AO was that it was cheaper doing it this way than to have to re-tool for an other line of lenses.

[Darryl Meister]

Explanation by AO was that it was cheaper doing it this way than to have to re-tool for an other line of lenses.

Then it sounds like you got a hell of a deal on those Amoptics. ;)

I was actually referring to their original 6.00 Base toric series sold under their brand name "Centex," which were different from the Tillyer lenses.

[vikramg]

Darryl now you are at it ..

Can you name for us the law which states that the amount of
astigmatism present in a progressive lens will always be equal/proportional to the addition power ...

No matter the technology of production ? (single/freeform/dual/???)

I am sure we can call it the miester's law of progressive design

[Darryl Meister]

Can you name for us the law which states that the amount of
astigmatism present in a progressive lens will always be equal/proportional to the addition power ...

It's basically a consequence of a theorem first formalized by Minkwitz, which states that the rate of change in astigmatism away from the center line of the progressive corridor is equal to twice the rate of change in mean power along the center line. Since the rate of change in mean power is proportional to the Add power, the rate of change in astigmatism (at least near the corridor) is also proportional to the Add power.

[Darryl Meister]

They are all way overpriced as the manufacturing of them does not cost a penny more than to cast and make a regular bifocal

Chris, this isn't the first time you've made this assertion, and seem you genuinely convinced of it, so I'll spend a moment to enumerate some of the additional costs associated with progressive lens manufacturing:

Research and development costs. Unless you're a lens manufacturer using an OEM design from another company, there are numerous research and development costs associated with designing a progressive lens. The major lens manufacturers will have vision science programs in place to research optimum lens design configurations, test prototype designs, validate lens designs, conduct wearer trials, and so on. And, of course, lens designers are needed to characterize, calculate, and optimize the actual designs. This is usually done in conjunction with proprietary software created by computer programmers working for the company.

And this design work must be done separately for each Base curve + Add power + lens material combination. For even a modest lens series with 12 Adds, 5 Base curves, and 4 lens materials, you are looking at a minimum of 240 individual designs, which will all need to be tweaked. This requires hundreds of hours of design work and intensive computing resources. Engineers are then needed to translate these designs into actual molds. On the other hand, there are no lens design or research and development costs associated with traditional bifocals.

Mold making and manufacturing costs. Making a glass bifocal mold is very similar in principle to making glass bifocal. The process employs relatively simple equipment designed to produce basic spherical surfaces. Progressive lens molds, on the other hand, require extremely expensive computer-controlled milling machines or lathes for cutting the molds (or mold formers, depending upon the system).

Further, because of shrinkage and related manufacturing variances, each lens design often has to be "tweaked" or iterated to achieve the target surface powers and performance after casting or injection-molding, which means that each Base and Add combination might require several mold making attempts before getting it just right. Moreover, each progressive lens mold must be individually designed, and must also be individually iterated. The measurement tools used in this process are also much more sophisticated and expensive than the simple sag gauges and lensometers used to verify bifocals.

Then, when you're finally done with each mold, you have to have an expensive etching system in place for the semi-visible engravings that appear on the final product. And you also need an inking system in place to mark each blank before packaging. These additional costs also mean that any yield loss will impact your bottom line that much more.

I'll skip the additional costs involved after the manufacturing process.

[Chris Ryser]

........................so I'll spend a moment to enumerate some of the additional costs associated with progressive lens manufacturing

Darryll, that was a pretty good description of the work involved to make them lenses. Im am sure the Optiboard m,embers will enjoy reading it as it is very educational.


Compare this to a toll road or bridge which usually becomes a free passage after the original cost is paid off after a certain time span.

The pharmaceutical business is the leader in charging off the initial developing cost as long as the patents are protecting them, which is usually 15 to 20 years depending on the country.

Even if sales and profits have been in the high range the price will not go lower as long as the protection exist's, even if the original investment has been paid off and been neutralized years ago.

The same idea seems to exist in the optical lens manufacturing with the difference that there are so called new designs coming every time the clock turns to midnight, which lets you to justify new design cost's.

[Darryl Meister]

Compare this to a toll road or bridge which usually becomes a free passage after the original cost is paid off after a certain time span.

I don't know. In San Francisco, the toll bridge just got more expensive with time...

Even if sales and profits have been in the high range the price will not go lower as long as the protection exist's, even if the original investment has been paid off and been neutralized years ago.

Actually, it's like that in any industry. And it is also why you can get a lens like VIP or AO Pro for a lot less than SOLAOne. If you really want someone to pick on, you should go ask Apple why they're still charging $300 for iPods.

The same idea seems to exist in the optical lens manufacturing with the difference that there are so called new designs coming every time the clock turns to midnight, which lets you to justify new design cost's.

The costs involved are still there for each and every new lens we design. And we certainly don't dismantle our R&D department in between product launches.