Free form lens verification for labs

[DanLiv]

I have been looking into a new digital lab and had several detailed questions for them, one of which is their quality control process for verifying accurate free form lenses are being produced. The rep checked with the lab manager and the response I got was they check power on a manual lensometer from 1/8th to 1/16th diopters.

First of all, how the heck do you get a reproducable manual lensometer measurement down to 1/16th diopter? Next, this does nothing to verify the overall lens is being fabricated true to design. *I* measure power and match it up to the lab's supplied compensated Rx, and from there I simply have to trust the lab fabricated the rest of the design properly. But there are sophisticated lens mapping techniques to truly verify the entire design has been faithfully produced, aren't there? My understanding is they are a pain, but that good digital labs will frequently pull a sample job and go through the full test. If the design is accurate, keep going. If not, halt surfacing and recalibrate. Is this correct?

If this is the case, what sort of verification and quality control process ought I to demand from a digital lab? Especially when dealing with private label and house digital designs, what is reasonable to expect from their verification techniques to make me confident the lenses I'm getting really are true to design?

Thanks!

[sharpstick777]

Good questions Dan, There are recently dual lens mappers that can help verify progressives, one is made by AR in Beligium, the other by Rotlex in Isreal. Tehre are still issues because there is a subjective element on where and when you reject a lens.

The machines are new, and expensive, so most labs don't have them. Even in the ones that do, not all lenses are verified. Its fairly time intensive. Its my wish list though. Here is a link to one: http://www.ar.be/produits/DUAL_LENSMAPPER5c25p.pdf

Expect more of these in the next few years, but until then we are unfortunately trusting the software and machines. They will eventually become common, but its an emerging technology for labs right now.

I have been looking into a new digital lab and had several detailed questions for them, one of which is their quality control process for verifying accurate free form lenses are being produced. The rep checked with the lab manager and the response I got was they check power on a manual lensometer from 1/8th to 1/16th diopters.

First of all, how the heck do you get a reproducable manual lensometer measurement down to 1/16th diopter? Next, this does nothing to verify the overall lens is being fabricated true to design. *I* measure power and match it up to the lab's supplied compensated Rx, and from there I simply have to trust the lab fabricated the rest of the design properly. But there are sophisticated lens mapping techniques to truly verify the entire design has been faithfully produced, aren't there? My understanding is they are a pain, but that good digital labs will frequently pull a sample job and go through the full test. If the design is accurate, keep going. If not, halt surfacing and recalibrate. Is this correct?

If this is the case, what sort of verification and quality control process ought I to demand from a digital lab? Especially when dealing with private label and house digital designs, what is reasonable to expect from their verification techniques to make me confident the lenses I'm getting really are true to design?

Thanks!

[DanLiv]

Expect more of these in the next few years, but until then we are unfortunately trusting the software and machines. They will eventually become common, but its an emerging technology for labs right now.

Yikes. That's a lot of trust. Especially for house brands or independent digital labs. I know brand digital lenses like Essilor/Varilux, Shamir, Zeiss, etc. have stringent controls over lab production, presumably so they can better guarantee the finished product. But if it's so hard to verify the lenses, how do the independent non-brand digital labs even know *themselves* if the lenses are right, much less being able to guarantee and demonstrate to the provider.

There's always just the "try it and see" approach, but then I remember my early days in a mediocre quality retail lab when we would surface something as much as .25 diopters off and management would say "try it and see." Just because no one has problems with it doesn't mean it's right or that the optical or customer are getting the value of the product. It seems crazy with the expense of some of the top tier digital lenses that they really can't give me any proof the lenses are right.

And when a lab tells me they verify their super-dooper-higher-tech-than-everybody-else lenses with a manual lensometer, I really have trouble finding confidence.

Anyone else have qualms about trusting such quality claims from independent digital labs?

[sharpstick777]

Yikes. That's a lot of trust. Especially for house brands or independent digital labs. I know brand digital lenses like Essilor/Varilux, Shamir, Zeiss, etc. have stringent controls over lab production, presumably so they can better guarantee the finished product. But if it's so hard to verify the lenses, how do the independent non-brand digital labs even know *themselves* if the lenses are right, much less being able to guarantee and demonstrate to the provider.

Don't be too impress by the names. Most of the so called "stringent" standards are not that stringent. Right now, some manfacturers require some lens samples to be sent in for verificiation. But the sample amounts are low for cost reasons. Certification is set mainly by the generator you use, not by any advance technic or knowledge.

Remember what we are up against. The average lap or tool is off by .07 D to start with, in the correct RX. In a full lab, I need over 4000 laps or tools to cover every base curve power and material option, and if I have 1000 jobs in progress, that means a lot of tools are missing at any given time. So most labs substitute for the 2nd and 3rd (yes, even the 4th) best tool curvatures by the lab software, because when they go to the tool room the tool they need is often missing. Sure the can make a tool (thats what they will tell you) but it slows the line down, because they are often made on same generators that make the lenses. There is no money in making tools. They substitute, and your lens is off before the first pad hits the blank.

Add those together, and ANY digital lens is going to be far more accurate than a grinder.

I would trust a generic FF lens over a precision grinder any day of the week.

[optimensch]

You raise a point I have thought about. Full backside milled lenses are all basically like little intricate sculptures, unique 'one offs' , if u will. Coventional progressives are cast so the front surface is a molded finished product and normal sphere-cylindrical surfacing on the backside finishes the job. I am convinced that the quality is more consistent on conventionals and that we wind up passing off plenty of defects unwittingly. I spoke with the head of a big lab who more or less agreed with this premise. I do not believe we have fewer non adapts with these lenses and I think the hype is ridiculous over-promising. The really good conventionals are disappearing it seems and are being dismissed as inferior. What a crock.

[optimensch]

But if the rx on a 'grinder' is measurable to .12 and is accurate to within .12, what's the problem? Anyone can read the final power, if it's off it's going back. My phoropter has .25 d steps, what do I give hoot about .01 diopter steps on the lens?

[optimensch]

Nah, this is a load of hype, backed by pseudo science. Show me double blind studies that back the claims of any of this free form mania.

[HindSight2020]

You raise a point I have thought about. Full backside milled lenses are all basically like little intricate sculptures, unique 'one offs' , if u will. Coventional progressives are cast so the front surface is a molded finished product and normal sphere-cylindrical surfacing on the backside finishes the job. I am convinced that the quality is more consistent on conventionals and that we wind up passing off plenty of defects unwittingly. I spoke with the head of a big lab who more or less agreed with this premise. I do not believe we have fewer non adapts with these lenses and I think the hype is ridiculous over-promising. The really good conventionals are disappearing it seems and are being dismissed as inferior. What a crock.

I disagree, it's not a crock...although there is some blind faith involved when it comes to FF design verification, the technology is far superior when compared to conventionals. As you mentioned, conventional blanks are cast with entire design on the front surface and simply milled off with a two axis generator on the back to provide the Rx. Fined and polished and voila, that's pretty much it...the result is a hard design full of abberations and narrow corridors to view your world through. This fact alone has kept chiropractors employed and I'm rather surprised the non-adapt percentages havent been higher.

With the FF designs, the optimization design calculations for the wearer coupled with advanced processing technology results in a far superior product with wider corridors and reduced lens abberations. I continuously map the old conventional designs in the lab and compare them side by side to the FF designs and you can clearly see the improvements. As a supplier of all brands, I can tell you with confidence that FF lenses when measured and dispensed properly are not over hyped. That said, I can also tell you there are FF design levels - good, better, etc...but even at the good level, it is far superior to basic conventional.

Part of the adaptation issues dispensers are having in attempting to put patients into new technology, yet they are used to hardness and horrible abberations becuase that's what they've worn for many years and their brain is used to it. It's like that old pair of jeans or old pair of shoes, they look like crap, yet they still feel great to wear when compared to the slimmer fit pants with expandable waist and new iron free material. For the longest time, I was getting all PAL orders from some of my customers with binoclar PD's on each and every order - what a horrible mistake yet the easiest to correct! It shocks me that most offices still don't even have a pupilometer and are using a PD ruler and marker - mm's and paralax error come to mind?

In fact, my ratio of FF vs. conventional is now about 70/30 and my non-adapt ratio is less than 1%. A successful design is only as good as it's fitting - I have gone out and trained all of my customers to ensure a successful fit - the first attempt results with the patient, dispenser and supplier being happy, not to mention all the time we saved in preventing the remake.

If your supplier is carrying these new products yet doesn't believe in them, I'd say go out and find a new supplier. One that is knowledgeable, able and willing to train your entire office not only on how to sell and position it to the patient, but also how to fit and dispense it properly.

[Jubilee]

Well there are also the backside costs..

For a traditional molded progressive, not only do you have the design process, but then the costs for producing the molds, the blanks, etc. The margins are really low on the wholesale lab side, and some of those blanks cost enough that by the time all discounts are applied.. any remake is at a loss. We are a small wholesale lab, and I spent over $50k just to bring in two progressive designs in MOST base/adds for plastic/poly and the photo for each. This was not even a *premium* brand.

When I can replace hundreds of thousands of dollars tied up in stock by covering all the most requested lens designs by buying a generator that will allow me to "program" in the designs and make it more "precise" then it will reduce the cost of goods in the long run, make my business more profitable, and will drive down the cost to you.. making you more profitable.

As for the "hype" .. have you tried one?

Why get a HD tv when you can see on a traditional one just fine?

For myself, things are sharper.. clearer.. and that makes my glasses more comfortable to me.

[Judy Canty]

Nah, this is a load of hype, backed by pseudo science. Show me double blind studies that back the claims of any of this free form mania.

Then, for pity's sake, don't fit them. I've run across people in this industry who believe AR is BS; photochromics are dangerous and any material other than glass is worthless. If you don't believe in a product, don't use or recommend it.

PS. The world is not flat. Fact.

[GokhanSF]

Then, for pity's sake, don't fit them. I've run across people in this industry who believe AR is BS; photochromics are dangerous and any material other than glass is worthless. If you don't believe in a product, don't use or recommend it.

PS. The world is not flat. Fact.

+1 for Judy's comments

Optimensch, personally I am glad you are not my or any of my family members OD.

[MakeOptics]

You raise a point I have thought about. Full backside milled lenses are all basically like little intricate sculptures, unique 'one offs' , if u will. Coventional progressives are cast so the front surface is a molded finished product and normal sphere-cylindrical surfacing on the backside finishes the job. I am convinced that the quality is more consistent on conventionals and that we wind up passing off plenty of defects unwittingly. I spoke with the head of a big lab who more or less agreed with this premise. I do not believe we have fewer non adapts with these lenses and I think the hype is ridiculous over-promising. The really good conventionals are disappearing it seems and are being dismissed as inferior. What a crock.

+1, I sell and like fitting digital designs but your right the accuracy is not guarenteed and the quality delivered is impossible for the dispenser to verify. "Trust", is essential in the supply chain. If your lab didn't earn your trust before the age of digital they definately shouldn't have your trust with your digital work. You are correct with the surface quality of the traditional compared to the digital as well. Ugly truths so your not going to be popular, but thanks for sharing your opinion.

[GokhanSF]

If you don't trust your lab why do you even work with them? There are labs who invested their money to ensure they can verify the design and map the lens prior sending your way. Others mostly rely on the software and the generator will put out what they are supposed to.

80% of my lens sales are digital and haven't had a single complain from patients and most even says they can see much crisper than their previous lenses.

[GokhanSF]

I do not believe we have fewer non adapts with these lenses and I think the hype is ridiculous over-promising.

You have to remember technology is as good as the user. If you don't know how to fit a digital lens and which digital design to use for each patient's needs than you will have higher non adapt rate than conventional progressive.

[nicksims]

This isn't an answer to your question, but I feel very related regarding accuracy. I haven't pestered my lab yet, but am about to.
When I receive digital lenses, edged or uncuts, and I have the compensated rx in hand, I question the numbers. On the page is the orig. rx as well as what I am to read. What I question is the stage at which the "Rx In Lensometer" is determined.

Recent example- I received uncuts. In this particular case I needed to send them back with the frame to be edged. When it arrived edged, I compared the two documents and the "Rx In Lensometer" numbers were different for the edged versus uncuts. Shouldn't they be EXACTLY the same. I would expect that I should be reading numbers that were the original calculated numbers to which the lenses were made. It seems like they are sending me what they are reading in the lensometer, hence why I had 2 different sets of numbers from uncuts to edged. The value differences were negligible, but why should they be different? It just looks like they are sending me "result" numbers (post-fabrication) instead of the original calculated compensated rx for comparison. Or am I looking at this all wrong? Shouldn't 50 sets (or an infinite #) of lenses made with the same rx/frame details be the same- and I mean the compensated rx to which I would compare the final set, not the actual lensometer reading which I would expect to have slight variations?

[MakeOptics]

This isn't an answer to your question, but I feel very related regarding accuracy. I haven't pestered my lab yet, but am about to.
When I receive digital lenses, edged or uncuts, and I have the compensated rx in hand, I question the numbers. On the page is the orig. rx as well as what I am to read. What I question is the stage at which the "Rx In Lensometer" is determined.

Recent example- I received uncuts. In this particular case I needed to send them back with the frame to be edged. When it arrived edged, I compared the two documents and the "Rx In Lensometer" numbers were different for the edged versus uncuts. Shouldn't they be EXACTLY the same. I would expect that I should be reading numbers that were the original calculated numbers to which the lenses were made. It seems like they are sending me what they are reading in the lensometer, hence why I had 2 different sets of numbers from uncuts to edged. The value differences were negligible, but why should they be different? It just looks like they are sending me "result" numbers (post-fabrication) instead of the original calculated compensated rx for comparison. Or am I looking at this all wrong? Shouldn't 50 sets (or an infinite #) of lenses made with the same rx/frame details be the same- and I mean the compensated rx to which I would compare the final set, not the actual lensometer reading which I would expect to have slight variations?

That particular scenario may still point to a valid lens. If you supplied frame data the lab would fabricate it assuming your measurements were accurate, but once they get the frame they could trace it and find slight differences between your supplied numbers and their particular tracers. No need to be alarmed.

You have to remember technology is as good as the user. If you don't know how to fit a digital lens and which digital design to use for each patient's needs than you will have higher non adapt rate than conventional progressive.

Does that statement apply on the lab level as well? The reason I ask is there is no way to verify the design on the dispensers level which leaves the dispenser in a blind scenario when verifying lenses. This is a limitation to the technology, this limitation can be exploited by labs. It is important to practice caution when choosing a vendor of lenses, it is also important to understand the technology we work with. Selling a higher percentage of a product does not make you the authority and 80% being a nice round number with very little jagged edges implies that your number is anecdotal at best. I have had more then a few scenarios where I have had a non-adapt and I just ignore the fact that every time I call the lab to switch lens designs they always tell me they haven't had a non-adapt yet. So I have been the first non-adapt with my lab 5 to 6 times, that must be a record. I wonder how many others have been the first non-adapt to my labs FF lenses? Anyway, great technology and I feel as though it's still not being utilized to the max yet so I anxiously await the next generations designs.

[nicksims]

PhiTrace,
I hadn't considered that. The numbers were so similar- that makes sense.
Thank you.

[seymourspots1]

Friend, you are seriously overthinking this. Trust the technology. Put the glasses on your customer's face...watch their reaction and run with it. It is not realistic to expect a lab to spend half a mil on digital equipment and then have to spend another $100K on a dual lens mapper or a lensometer that can read digital powers. Until every ECP and optician has such a lensometer to check the jobs, then its not a realistic expectation. Don't drive your lab nuts with questions about powers. This is a new technology for everyone. Remember, the eye can accept tolerances. If a compensated rx looks nothing like the original dr's rx and the customer still sees splendidly out of it, what does that tell you?? The proof is in the pudding. It works.
Trust the technology and stop over thinking it.

[WFruit]

From a lab perspective: Yes, without a lens mapper, it's difficult to guarantee the perfect accuracy of the design. For powers, we use Humphry's 350 lens analyzers, set to measure in 0.01 diopter steps. For design quality, we send lenses to our current two free form software providers (Shamir and Seiko) to verify their accuracy, both power and design, four times a year, and whenever a new lens design in released or we purchase new equipment. So far none of the vendors have complained that we're making sure we're making their products correctly .

[HindSight2020]

Then, for pity's sake, don't fit them. I've run across people in this industry who believe AR is BS; photochromics are dangerous and any material other than glass is worthless. If you don't believe in a product, don't use or recommend it.

PS. The world is not flat. Fact.

+1

[optimensch]

interesting. So if your family's physician highly recommended treatments that are not tested scientifically with double blind studies, and just touts pharmaceutical company's unsubstantiated claims, that is a good doctor in your world.

[optimensch]

No one here has pointed to a study or a standard which shows these designs are actually better , or do what the manufacturers claim. No double blinds, no science. Just eat the pablum. And you question my scientific credentials?

[optimensch]

Be a sales person, and take the manufacturer's word for it. Ask no questions. The scientific method does not apply in optical. I thought there was something more here on these boards. A place to raise serious questions and get serious answers, or at least light a spark and get some feedback other than "im glad you are not my family's od" or "so dont fit them.". Not serious.

[optimensch]

"you have to have faith", if you don't "TRUST" your lab, find another. What a crock! Maybe the FDA should use those standards too when verifying pharma's claims. Are you serious?

[optimensch]

and it IS not about not "believing" in Digital lens processing. I want to know HOW any OD or Optician can VERIFY a single claim about any of these products in their offices other than "the patient told me they love it". That is ok for HOMEOPATHS and other quacks. Not for me.