Digital Lenses feed back

[shanbaum]

Shanbaum -- this grasshopper thanks you for your insight and wisdom!

Take the pebble from my hand...

[MikeAurelius]

*grin*

[Robert_S]

Just out of curiosity, have you EVER seen the results of large wearer trials in which the "presented lens" did NOT preform well? Isn't this just another marketing ploy? What SHOULD count is how do YOUR patients or clients adapt. We are extremely proud of our Integrity brand (not a "house lens"). We put out name on it and stand behind it. The main reason we can offer Integrity at a lower price is that we are not paying for corporate marketing, national advertising or dispenser kickbacks. We count on our customers to know their patients AND their product. Just sayin'...

That's because what you receive is the end result of those wearer trials. If the lens performs anything other than perfectly, they tweak the design until they get the results they want, and there's nothing wrong with that approach. No lens company is going to produce a lens with high rates on non-tolerance as they won't make any money.

[sharpstick777]

In the case of Zeiss, however, they are using infinite point files because they generate the lens "on the fly," instead of having a pre-existing lens idea. What I have liked about Zeiss (if I understand anything) is that they do what I call real free form. Other manufacturers are using a limited number of point files (10,000 vs 800 per the example), meaning that basically, where as a traditional lens had ~100 different design variations (BC * Add * corridor, etc), the digital lenses have 10,000+ designs via modifications through cnc to the original 100.

This is true of the Individual and Choice Variable, but not of the lower priced Choice series I believe. Darryl could clarify that though.

[sharpstick777]

Standard point files are in fact two-dimensional arrays of sag values. The x and y coordinates are implied by the size of the array and the number of points (that is, there are no x and y values in the files - only z's). You might think that "the more points, the better", but that's really not the case. Machines ultimately have to produce tool paths that are continuous; they do this by curve-fitting given the supplied points. At some resolution, additional points are superfluous (the same is true of edgers, by the way). At least one generator provider was initially incapable of using very high-resolution files, when the standard point file started to be used around 2007.

Some LDS suppliers use "seed files" and some don't; Zeiss is not the only one that doesn't. In fact, some LDS use seed files for some designs and not for others. A seed file is essentially a shortcut, relieving the program of having to generate a starting surface every time. The seed file may not be a "point file" itself; it could be (for example) a set of coefficients for spline functions, which are used to produce continuous curves.

Thanks Robert, great addition to the discussion.

[sharpstick777]

I'm starting to believe that we've been duped. I have tried house brands, Premium brands, and everything in between. While there are some myopic pt's that see better out of the digitals, Hyperopes and minor powers do not seem to see that much of a difference.

Now I know this opinion will cause a ruckus, but I have better success out of traditionally surfaced progressives. I still dont know for sure if this is a buyers remorse issue or if the industry as a whole is trying to make more money out of us and the pt's.

I would respectfully disagree, I am working myself on a theorem that would demonstrated that free-form lenses (true 100% free-form) where the add is digitally processed can offer substantially reduced TDP (Total Potential Distortion is my own definition, but its a combination of unwanted irregular cylinder, unwanted prism, and offers focal point away from the macula). The key is first knowing which lenses are 100% free-form (some are hybrid, and not fully free-form), and then where those lenses are focusing their improvements. For example, an Auto II will not provide as wide a reading as an old fashioned Comfort so your reading patient may be disspointed. Years ago in the 1990's we began extensive follow ups with patients who received Free-form lenses (the term wasn't even used then) and we found that they had a substantial reduction in trouble driving at night, and that was with the old free-form designs. I can document higher patient satisfaction (when dispensed correctly), less trouble driving at night, less swim or sway, through extensive post dispensing interviews we did with early Free-form. Free-form though is like having a $1000 Titanium and Moon Rock #1 golf driver, I still have to use it with skill, and I will not get good on results if I try to putt. I would be better off with the putter from a mini-golf course.

[sharpstick777]

I think that your observation regarding the number of designs is correct - it is really hard for dispensers to understand the differences amongst them. You can look at power maps ad infinitum, but they don't tell you how the lens will actually perform. That's one of the reasons my friend Rick may chime in with a message about the importance of extensive wearer trials.

I have broken down a lot of Free-form maps into groups, or styles. There is far more variety among free-form lenses than their is with Grinders, as their should be. I have sent my progressive guide to a few people on this forum, and it would better if they commented on whether my guide will reduce this issue reasonably. We can learn a lot more about Progressive lenses and then dispense them with far more precision than we realize.

[sharpstick777]

Sharpstick, are you saying that a single premium free form progressive lens can contain up to 10,000 point files or that the lens design software contains over 10,000 point files variations?

The more variables you allow, and the higher the RX range, the more materials, etc, the more point files you will need. Total variations will be way over 10,000 quickly when you consider customized POW measurements so those lenses are most often rendered individually. Ever wonder why some brands stop at a certain RX even when you know its possible to surface in power beyond that? They are limiting their point files (and to some degree, improving their yield). Its simply a cost vs. return factor in many of those cases.

[sharpstick777]

With that being said are there any generators out there that cut so clean that you dont have to polish?

DAC used to make one, at least in CR-39 it didn't require polishing. But they went out of business, although they sold the generator to Chemat, who doesn't share the same reputation. That Generator was not certified to surface many brands though.

[sharpstick777]

Mike, direct surfacing never involves fining. The process depends almost totally on the generator producing a near-specular surface. The polishing operation is performed by only-slightly-glorified sphere machines (ok, some machine vendors may dispute that, but some of them are exactly that) using conformable laps, and it is crucial that the material removal in that stage of the process be uniform and very close to zero.

Gerber used to offer a polisher where the polishing medium actually tracked the point file instructions, however, they have discontinued that model for a simpler dumb polisher. My guess it was too slow, but they wouldn't tell me exactly why.

[MasterCrafter]

I would respectfully disagree, I am working myself on a theorem that would demonstrated that free-form lenses (true 100% free-form) where the add is digitally processed can offer substantially reduced TDP (Total Potential Distortion is my own definition, but its a combination of unwanted irregular cylinder, unwanted prism, and offers focal point away from the macula). The key is first knowing which lenses are 100% free-form (some are hybrid, and not fully free-form), and then where those lenses are focusing their improvements. For example, an Auto II will not provide as wide a reading as an old fashioned Comfort so your reading patient may be disspointed. Years ago in the 1990's we began extensive follow ups with patients who received Free-form lenses (the term wasn't even used then) and we found that they had a substantial reduction in trouble driving at night, and that was with the old free-form designs. I can document higher patient satisfaction (when dispensed correctly), less trouble driving at night, less swim or sway, through extensive post dispensing interviews we did with early Free-form. Free-form though is like having a $1000 Titanium and Moon Rock #1 golf driver, I still have to use it with skill, and I will not get good on results if I try to putt. I would be better off with the putter from a mini-golf course.

Thanks Sharp, You make a lot of sense. Your analogy puts it in layman's terms.

[shanbaum]

DAC used to make one, at least in CR-39 it didn't require polishing. But they went out of business, although they sold the generator to Chemat, who doesn't share the same reputation. That Generator was not certified to surface many brands though.

I've not seen a lens off any DAC generator that didn't require further treatment. My understanding is that Chemat bought the machine in order to integrate it with a cut-to-coat system (coating was their business prior to buying the DAC ophthalmic equipment) wherein the coating obviates the need for polishing.

[MikeAurelius]

It CAN be done, however, the time required to do it exceeds the time to generate and polish. It would require a single point cutter and an absurdly long cycle - 1-3 passes to hog, then a pass to fine, and a final pass to clean up. This is how a lot of high precision glass is made these days, albeit with an external polish cycle. Some exotic glass materials can be used straight off the generator.

Require air spindles turning at 50,000 rpm for the final pass.

Got $750K?

[Tallboy]

I have been using IOT software "inhouse" designs from a certain Pittsburgh based lab for the last 6 months. I have seamlessly switched over Zeiss/Varilux traditional and high end digital (everything but Varilux S / Individual 2 - which we haven't used)

The patient response to price / function has been great. No non-adapts that seem to be based in the lens design. As of right now the only lens I feel I should add to the portfolio I use in the lab is the Seiko Surmount because it sounds so much different than anything else.

Am I just wanting this to work, or have I stumbled onto a goldmine? Have these lenses gotten WAY better in design/fabrication in the last few years?

[ThatOneGuy]

I have been using IOT software "inhouse" designs from a certain Pittsburgh based lab for the last 6 months. I have seamlessly switched over Zeiss/Varilux traditional and high end digital (everything but Varilux S / Individual 2 - which we haven't used)

The patient response to price / function has been great. No non-adapts that seem to be based in the lens design. As of right now the only lens I feel I should add to the portfolio I use in the lab is the Seiko Surmount because it sounds so much different than anything else.

Am I just wanting this to work, or have I stumbled onto a goldmine? Have these lenses gotten WAY better in design/fabrication in the last few years?

I stand by my original assertion that design is still king over process.

From a patient "capture" perspective, it is merely a matter of targeting the strengths and weaknesses of a given lens design, and addressing them. If a previous zeiss/varilux wearer walks in and their CC is "these glasses were too expensive last time," then addressing the cost issue may garner a sale.

On a side note to Shanbaum, thank you for articulating what I've never tried to explain before. I really appreciate your insight and obvious experience.

[lightbender27]

I have ,my boss wearing the new Camber lens by Younger. He loves it so far, gets a lot of intermediate. Perfecta is another fav of his.

[Bill West]

I personally don't think names matter a lot on a true free form. I will say though, as with all progressives, it is the fit that matters most.Start with a good fitting frame and do a good job on the lenses and bingo, happy customer.