# Optical Forums > General Optics and Eyecare Discussion Forum >  Poly for the win?

## shankay

Recently had some information given to us that Polycarbonate is now at the "top of the chain" for material due to recent improvements. I have reservations due to historical patterns that seem to lean against Poly for many patients. Does anyone have new info that would support the theory that Poly is now a better option than Trivex? Let's just assume we are talking about a -2.00 and will include a Premium AR. I'd love to hear thoughts. Thank you!

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## grudyfan13

> Recently had some information given to us that Polycarbonate is now at the "top of the chain" for material due to recent improvements


What exactly were the improvements made?  Was this from one particular supplier?  And which supplier said this?

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## shankay

It was information that was given at a training to my coworker. To my knowledge, The information was given to the teacher by way of someone from the vision council. I'm super curious as to what improvements have been made to the material. I'm wondering if anyone can shed some light as the info was vague.

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## grudyfan13

Taken directly from the Vision Council website:




> *Polycarbonate*Benefits: No-distortion, shatterproof lens for kids, active adults
> Polycarbonate lenses are thinner and lighter than standard plastic varieties, and also much more durable. Polycarbonate is ideal for strong prescriptions because it corrects vision without adding thickness, which can distort the wearer's appearance. Best of all, polycarbonate lenses are virtually unbreakable, making them a great choice for children and active adults.


Not sure if I'd be so bold as to proclaim poly as "distortion-free".  Also not sure if the information that you've heard is marketing fluff from the Vision Council or legitimate improvements.  A cursory search on the Google monster yielded little in the way of new information.

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## rbaker



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## dima

:Bounce:

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## dima

I think the only improvement was "low" heat extrusion mold system

But optima resolution and other did it this more than 10 years ago

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## lensmanmd

Atoric and aspheric backside freeform processing has reduced the off axis aberrations.  STP processing using the turning tip has eliminated the lap/pad compensation and heat induced aberrations from toric surfacing, providing cleaner finished optics, but I wouldn't put Poly at the top of lens pyramid.  

Poly has improved over the past 3 decades.  Processing has improved.  COGs and profitability are awesome for the labs.  Still, there are better materials on the market.

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## shankay

Great info. I appreciate the information!

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## ePii

I think the vast majority of patients are fine with poly. Trivex, is nothing magical, and is over used by people who think it's a must to be a high end optical. Its abbe value is no where near CR and will be thicker than poly, plus it is a nightmare to work with. I say use poly unless you have very good reason to think a specific patient has an issue with it.

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## lensmanmd

> I think the vast majority of patients are fine with poly. Trivex, is nothing magical, and is over used by people who think it's a must to be a high end optical. Its abbe value is no where near CR and will be thicker than poly, plus it is a nightmare to work with. I say use poly unless you have very good reason to think a specific patient has an issue with it.


Agreed that TVX is overused, but considering its specific gravity and impact resistance, for low to mid RX, it fills the need very well.  3 piece, nylor, sports and safety, TVX beats CR39 hands down.  For those that are sensitive to CA, Poly is not a great material.  1.6 would be a better alternative for mid-high RXs.  

Fitted properly, Poly is an acceptable material.  We process over 60% of RXs in poly with less than 0.2% non-adapt, of which most are high decentration orders.  Better frame fit, better optics and cosmetics.......

There are many of us that can switch between CR39, TVX and Poly with no visual artifacts.  So, Poly is not an evil material.

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## ePii

Agreed. It is lighter, and thus does have a place, but considering how difficult it is to process it should not be a default. There are lots of offices that proudly say that they don't use CR or Poly and put everyone in Trivex. This makes zero sense.

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## vfpamp

Not all polycarbonate are made equal. You can't generalize. Trivex and CR-39 are mostly coming from the same places. Poly is being built everywhere, with all types of procedures and resin qualities. There's no one controlling minimum standards. Top-notch poly is better than Trivex. But can also more expensive than Trivex. The average poly in the retail market is just fine. Most people won't see any difference.

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## ePii

Most poly is fine. if you are buy from a reputable lab they are getting their poly from Vision Ease, Essilor, Zeiss etc. And even Somo is fine. I really think you can generalize since you have to be crazy motivated to save pennies on the lenses to find "bad" poly.

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## vfpamp

> I really think you can generalize since you have to be crazy motivated to save pennies on the lenses to find "bad" poly.


You don't need to be crazy motivated. You just need to operate an on-line retailer to get all the motivation you need to sell crap poly. Tons of crap poly.

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## pneese

> I think the vast majority of patients are fine with poly. Trivex, is nothing magical, and is over used by people who think it's a must to be a high end optical. Its abbe value is no where near CR and will be thicker than poly, plus it is a nightmare to work with. I say use poly unless you have very good reason to think a specific patient has an issue with it.


I will politely and respectfully disagree.

Trivex has a better abbe value, it does not have the CA issues that polycarbonate has, it has better tensile strength (more ideal for half-eyes and rimless frames), it has slightly better light transmittance, and like someone earlier mentioned it has a lower center of gravity.

If a customer is fitted correctly (ideally I know) where there is not a significant amount of decentration than the fact that it's 10% more thicker won't mean much. By the time we are getting into higher prescriptions CYL or SPH where the difference will matter we should be fitting people with a Hi-Index lens anyway.

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## Kwill212

> Top-notch poly is better than Trivex.


Where would one source "top-notch poly", specifically what manufacturer makes it? What makes it objectively "better" than trivex? Again specifics would be great.

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## ak47

I will less than respectfully disagree.  Whoever is selling that information is either clueless or full of sh*t.  Poly has its place, and is the best choice in a few, select situations.  Nine times out of ten it is absolutely not the BEST choice.  But, if you want your clientele to become frustrated when their lenses chip and crack, please use poly.  They will then become your former clientele.

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## vfpamp

> Where would one source "top-notch poly", specifically what manufacturer makes it? What makes it objectively "better" than trivex? Again specifics would be great.


I wouldn't know which US optical labs are working with good poly. We work more closely to the precision optics folks in China that make lenses for scientific equipment (microscopes, telescopes, etc). But, the samples I have achieve Abbe of 43-47, at indexes of refraction of 1.55–1.56 and better scratch resistance than Trivex at a slightly higher UV protection on our tests. What attracted us to this particular technology was the fact that the remaining chromatic aberration was concentrated in the 400-500nm range (violet). The material's index of refraction is 1.56+/-0.5 from 500nm to 830nm but 158 at 400nm. This is particularly good for green/red calibration of devices. To the best of my understanding, the property comes from the use of carbonyl sulfide instead of the usual thiols and phosgene polymerization method. Looks like it's also a "greener" option to the manufacturing of polycarbonate (at least, that's what they sell).

The Abbe number (more precisely, the index of refraction per wavelength of the material) is what makes it "objectively better" for me. But I expect every optician to have their own usually-contrasting notions of "better".

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## Kwill212

> I wouldn't know which US optical labs are working with good poly. We work more closely to the precision optics folks in China that make lenses for scientific equipment (microscopes, telescopes, etc). But, the samples I have achieve Abbe of 43-47, at indexes of refraction of 1.551.56 and better scratch resistance than Trivex at a slightly higher UV protection on our tests. What attracted us to this particular technology was the fact that the remaining chromatic aberration was concentrated in the 400-500nm range (violet). The material's index of refraction is 1.56+/-0.5 from 500nm to 830nm but 158 at 400nm. This is particularly good for green/red calibration of devices. To the best of my understanding, the property comes from the use of carbonyl sulfide instead of the usual thiols and phosgene polymerization method. Looks like it's also a "greener" option to the manufacturing of polycarbonate (at least, that's what they sell).
> 
> The Abbe number (more precisely, the index of refraction per wavelength of the material) is what makes it "objectively better" for me. But I expect every optician to have their own usually-contrasting notions of "better".


I appreciate the detailed response. Is anyone using this material in eyeglasses? Is it called polycarbonate by the manufacturer? Seems like you are talking about a completely different material than what opticians would call Polycarbonate. Do you have a link to the Precision Optics folk in China?

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## Uilleann

The sheer amount of fear-mongering and misunderstood facts about poly, and CA in this thread are laughable!  But keep on pushing that trivex folks.  PPG thanks you from the bottom of their pocket book.  LOL
 :Giggle:

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## ePii

Anyone who swears by Trivex should first have to work in a lab for a year then say how they feel. Trivex is fine but Poly is better when all things factors are considered and compared, i.e price, ease, thickness, weight and even abbe value. Btw CR is still optically the best organic material we have. Most people just get indoctrinated by their Hoya or Younger rep, most patients can't tell the difference.

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## Kwill212

> Anyone who swears by Trivex should first have to work in a lab for a year then say how they feel.


Why, that makes no sense. If you run the lab and think Trivex is too hard to process, or wears out the equipment too much, either don't offer it or charge accordingly for it.

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## Robert_S

We use poly for a tiny, tiny amount of jobs because our company considers other materials better in most situations. I would say we have more issues with the few jobs we sell in poly than we do with the majority of jobs we sell in trivex. It cracks and stars, something I've never seen happen with trivex. And we don't buy 'cheap' poly.

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## ePii

It's not that Trixex is too hard to work with, it's that it's notably harder to work than other materials without offering significant benefits. I'd rather have optical professionals be a bit more critical about the information that they get indoctrinated with. The fear mongering and propaganda in this industry is truly destructive, and very few people even know when they're being lied to by the oligarchs.

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## lensmanmd

We processed 49926 pairs of poly in 2019.  0.08% were returned for cracking.

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## pneese

> It's not that Trixex is too hard to work with, it's that it's notably harder to work than other materials without offering significant benefits. I'd rather have optical professionals be a bit more critical about the information that they get indoctrinated with. The fear mongering and propaganda in this industry is truly destructive, and very few people even know when they're being lied to by the oligarchs.


There is no fear mongering, polycarbonate clearly is a worse lens material. I've never heard any specs or facts that have convinced me otherwise. Do you have sources you can link for us?

Don't get me wrong, I sympathize when you say its a pain to work with but I am more worried about my customer's sight than how much more work we would have to do.

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## lensmanmd

> Why, that makes no sense. If you run the lab and think Trivex is too hard to process, or wears out the equipment too much, either don't offer it or charge accordingly for it.


I run a full service lab.  Trivex is no more difficult to work with than poly.  Surface macros are basically poly macros.  Edged settings are basically poly setting.  
Trivex is tougher on wet edger roughing wheels.  Generator diamonds and turning tips wear a little quicker, sure, but not by large numbers.  Labs do charge more for Trivex due to lens and consumables costs.  
My gripe with Trivex is not processing costs.  It lies specifically with those that do not know when to or how to properly sell it.

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## vfpamp

> We use poly for a tiny, tiny amount of jobs because our company considers other materials better in most situations. I would say we have more issues with the few jobs we sell in poly than we do with the majority of jobs we sell in trivex. It cracks and stars, something I've never seen happen with trivex. And we don't buy 'cheap' poly.


Have you study the reasons for the cracks? Most of the time is a chemical compound that's being used to clean or to lubricate the machines. Tiny amounts of ester-based additives can easily crack the lens. Ammonia (Windex or 409) will damage. And obviously you should avoid all types for solvents, propanol, etc. Here's a starting point for your research: https://www.calpaclab.com/polycarbon...ibility-chart/ :)

Your poly source should be able to give you a list that is more appropriate to the specific mixture he is using to create the lens.

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## Robert_S

What is fear mongering about stating facts? Trivex is optically better, lighter, less chemically reactive and stronger than poly and therefore preferential in almost all cases. Doesn't mean poly is going to kill anyone, but then neither is not having AR. 

Part of our role as optical professionals is to drive the standard of our industry forward.

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## Robert_S

> Have you study the reasons for the cracks? Most of the time is a chemical compound that's being used to clean or to lubricate the machines. Tiny amounts of ester-based additives can easily crack the lens. Ammonia (Windex or 409) will damage. And obviously you should avoid all types for solvents, propanol, etc. Here's a starting point for your research: https://www.calpaclab.com/polycarbon...ibility-chart/ :)
> 
> Your poly source should be able to give you a list that is more appropriate to the specific mixture he is using to create the lens.


I appreciate the advice, genuinely. Thank you for your suggestions. 

But at the same time, if a material is so sensitive that trace amounts of a substance can crack it, that's even more of a reason for me to avoid it. It's actually not fair on the end user, who is surely going to also come into contact with trace amounts of substances like Windex, to be honest.

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## lensmanmd

Poly is stronger than Trivex, especially after AR is applied, in terms of impact resistance at the same thickness.   Trivex is more chemical resistant, lighter overall and has higher tensile strength.  
In terms of thickness to weight ratio, poly wins with higher RXs.  In terms of thickness, weight and chemical resistance, 160 wins.  
If optics is your primary concern, fit the best frame first.  Then decide on lens materials that best fits the patients’ needs, not yours.  This is the opticians’ primary responsibility, otherwise, you are nothing but a frame stylist.

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## vfpamp

> Part of our role as optical professionals is to drive the standard of our industry forward.


Then we should be talking about N-BK7 Glass. :)

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## vfpamp

> But at the same time, if a material is so sensitive that trace amounts of a substance can crack it, that's even more of a reason for me to avoid it. It's actually not fair on the end user, who is surely going to also come into contact with trace amounts of substances like Windex, to be honest.


Well, it's sensitive because your are cutting, grinding and polishing. Exposing the raw compound. After you apply the protective coatings, it should not crack at all. Like what lensmanmd said: ~0.08% is normal. 

We put poly in our phoropter and I have not seen any of them crack yet. 380,000 lenses shipped.

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## Robert_S

> Poly is stronger than Trivex, especially after AR is applied, in terms of impact resistance at the same thickness.   Trivex is more chemical resistant, lighter overall and has higher tensile strength.  
> In terms of thickness to weight ratio, poly wins with higher RXs.  In terms of thickness, weight and chemical resistance, 160 wins.  
> If optics is your primary concern, fit the best frame first.  Then decide on lens materials that best fits the patients’ needs, not yours.  This is the opticians’ primary responsibility, otherwise, you are nothing but a frame stylist.


Poly is 'stronger' in a totally insignificant way. Trivex is less prone to chipping, which is what the customer is most concerned about. 

In what way does trivex fit 'my' needs? What a ridiculous comment. 

Maybe you should stop trying to defend yourself picking the cheaper and easier option by selecting polycarbonate. 

In any scenario where polycarbonate is preferential to trivex, tribrid would be better anyway.

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## Robert_S

> Well, it's sensitive because your are cutting, grinding and polishing. Exposing the raw compound. After you apply the protective coatings, it should not crack at all. Like what lensmanmd said: ~0.08% is normal. 
> 
> We put poly in our phoropter and I have not seen any of them crack yet. 380,000 lenses shipped.


Not exactly the same as them being glazed into frames being worn by actual people, though, is it?

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## vfpamp

> Not exactly the same as them being glazed into frames being worn by actual people, though, is it?


Correct. But my comparison was related to your description of cracks during the lab work. Not after the patient has received it. At the lab, where you can control everything, it should never crack.

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## Robert_S

Did I say it happened in the lab? If it did, I would be blaming myself.

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## vfpamp

> Did I say it happened in the lab? If it did, I would be blaming myself.


My bad. You mentioned jobs, so I assumed it was during my the job execution.

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## ePii

But why are offices using trivex instead of cr in low rxs. Trivex is fine. It’s just not that special and I think there is a lot of unjustified snobbery around using it.

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## Robert_S

UV protection?

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## pknsbeans

Personally, I believe Trivex became obsolete when Tribrid was released.  Consider, in order of retail price with selling points:
CR-39: base material, fine optics, no impact resistance
POLY: thinner, lighter, impact resistance, possibly worse optics for some people
Trivex: thicker than poly, impact resistance, optics similar to CR-39
1.60: thinner, better optics, no impact resistance
Tribrid: 1.60 with impact resistance

From the lab I had been using, Tribrid was the same price as Trivex.  I don't know about the uncuts. But from a consumer perspective, Trivex serves only to muddy up my options.  I can get a lens that's clear, that's impact resistance, or that's thinner.  With poly and trivex, I get to pick 2 of those.  With Tribrid, you get all three.  What's Trivex purpose when Tribrid is available at a similar price?  And at that point, it makes sense to have a poly vs tribrid discussion with the patient on price vs quality. It's not just "which two of the three lens features do you value most?"

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## pneese

> Poly is stronger than Trivex, especially after AR is applied, in terms of impact resistance at the same thickness. Trivex is more chemical resistant, lighter overall and has higher tensile strength. 
> In terms of thickness to weight ratio, poly wins with higher RXs. In terms of thickness, weight and chemical resistance, 160 wins. 
> If optics is your primary concern, fit the best frame first. Then decide on lens materials that best fits the patients’ needs, not yours. This is the opticians’ primary responsibility, otherwise, you are nothing but a frame stylist.


Polycarbonate will never be the best fit for a patient's needs. By the time the difference in thickness is an issue, and it won't be if an optician is fitting a customer with the correct sized frame, a 1.67 or higher is the way to go not polycarbonate.

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## vfpamp

> Personally, I believe Trivex became obsolete when Tribrid was released.  Consider, in order of retail price with selling points:
> CR-39: base material, fine optics, no impact resistance
> POLY: thinner, lighter, impact resistance, possibly worse optics for some people
> Trivex: thicker than poly, impact resistance, optics similar to CR-39
> 1.60: thinner, better optics, no impact resistance
> Tribrid: 1.60 with impact resistance
> 
> From the lab I had been using, Tribrid was the same price as Trivex.  I don't know about the uncuts. But from a consumer perspective, Trivex serves only to muddy up my options.  I can get a lens that's clear, that's impact resistance, or that's thinner.  With poly and trivex, I get to pick 2 of those.  With Tribrid, you get all three.  What's Trivex purpose when Tribrid is available at a similar price?  And at that point, it makes sense to have a poly vs tribrid discussion with the patient on price vs quality. It's not just "which two of the three lens features do you value most?"


Well, PPG created CR-39, Trivex, Transitions and Tribrid. So, among these options their marketing materials tell the whole story: http://www.eyemax.co.il/wp-content/u...iew-2-Copy.pdf 

Tribrid is the natural evolution of Trivex, Like Windows 10 is the evolution of Windows 7.

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## Robert_S

I agree about tribrid. It's a shame that in the UK it is significantly more expensive...

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## lensmanmd

It is in the US, as well.  More than trivex, more than 167.

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## lensmanmd

> Polycarbonate will never be the best fit for a patient's needs. By the time the difference in thickness is an issue, and it won't be if an optician is fitting a customer with the correct sized frame, a 1.67 or higher is the way to go not polycarbonate.


You do understand that 
167 has a higher specific gravity than Poly, fight me.
167 has a higher specific gravity than CR39, fight me.
167 is not much better in terms of ABBE over Poly, fight me.
167 has a higher cost to the patient than poly, fight me.
Unless the frame calls for a groove/drill/safety needs, CR39 is optically better than everything but glass, fight me.
CR39 and Poly are the most cost effective material for the consumer, fight me.
167 is not a miracle material.  174 is not a miracle material.  The only miracle?  They improve your average sale, in turn, your paycheck.  They do not improve the bottom line of any business.  They should be used only when the RX calls for it, not for every RX.
Every material has its place in our industry.  The key is to understand when and why to advise the patient based on their needs, not yours.  Fight me.

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## lensmanmd

> UV protection?


Many materials are now available with UV420+.  IMO, offices use TVX b/c they can charge more.  I know of no office that sells TVX for the same price as poly or CR, but many no longer charge extra for UV.  
TVX advantages over CR?  Weight and impact resistance

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## lensmanmd

> Poly is 'stronger' in a totally insignificant way. Trivex is less prone to chipping, which is what the customer is most concerned about. 
> 
> In what way does trivex fit 'my' needs? What a ridiculous comment. 
> 
> Maybe you should stop trying to defend yourself picking the cheaper and easier option by selecting polycarbonate. 
> 
> In any scenario where polycarbonate is preferential to trivex, tribrid would be better anyway.


Poly is more impact resistant, less prone to heat damage, and when glazed properly, chipping/cracking is minimal.  Did I mention that out of close to 50000 pairs that we produced last year, we had 47 returned for this reason?  Poly 'non-adapts'?  Less than 1 %, of which were mostly poor frame fits to begin with.  
Fit your needs?  On average, it is more about commissions and revenue.  Trivex is more expensive than CR39 and Poly, therefor raises the AVG sale.  Higher AVG sale equates to higher spiffs/commissions.  Perhaps not you specifically, but true throughout the industry.  So, no, it is not a ridiculous statement.  It is about fitting the patients' needs.
Defending cheaper and easier option?  Again, no.  I am just defending the consumers' needs.  I am not disagreeing about the merits of Trivex.  I am just saying that it is an over-hyped product.
No arguments about tribrid.  There needs to be more competition by manufacturers to drive the price down before it can become more affordable to the average consumer.

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## Barry Santini

I agree poly has improved over the decades.
But CR39 has not. In fact, its quality has decreased to the point that I will not use it unless I absolutely have to.

B

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## Uilleann

> Poly is 'stronger' in a totally insignificant way...


And by extension - physics and basic math equally shows that Trivex is optically "superior" in a totally insignificant way as well.  

 :Giggle: 

PPG must have given free packets of Kool-Aid with every pair when it first launched!  LOL

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## Golfnorth

[QUOTE=Barry Santini;557782]I agree poly has improved over the decades.
But CR39 has not. In fact, its quality has decreased to the point that I will not use it unless I absolutely have to.


Barry....curious as to what your normal go to material is?

Regards,
Golfnorth

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## Barry Santini

I stock:
Essilor AR poly (EAAR)
Essilor poly (EAA)
Hoya Phoenix EX3 (trivex)
Zeiss Duravision Blu Protect (Poly version)

I order surfaced:
Poly
Trivex
1.60
CR39
1.67
1.74
In that order.

B

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## CCGREEN

> What is fear mongering about stating facts? Trivex is optically better, lighter, less chemically reactive and stronger than poly and therefore preferential in almost all cases. Doesn't mean poly is going to kill anyone, but then neither is not having AR. 
> 
> Part of our role as optical professionals is to drive the standard of our industry forward.


I have yet to ever pick up a trivex lens of equal size, thickness and power and find it to be lighter in weight then poly.

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## pneese

> You do understand that 
> 167 has a higher specific gravity than Poly, fight me.
> 167 has a higher specific gravity than CR39, fight me.
> 167 is not much better in terms of ABBE over Poly, fight me.
> 167 has a higher cost to the patient than poly, fight me.
> Unless the frame calls for a groove/drill/safety needs, CR39 is optically better than everything but glass, fight me.
> CR39 and Poly are the most cost effective material for the consumer, fight me.
> 167 is not a miracle material.  174 is not a miracle material.  The only miracle?  They improve your average sale, in turn, your paycheck.  They do not improve the bottom line of any business.  They should be used only when the RX calls for it, not for every RX.
> Every material has its place in our industry.  The key is to understand when and why to advise the patient based on their needs, not yours.  Fight me.


The majority of what you state I agree with. I don't think anyone was calling the 1.67 a miracle material and while it may not be much better in terms of it's ABBE value, I have never gotten complaints against 1.67 with regards to visual issues like I've received with Polycarbonate. While CR-39 and Polycarbonate may be the most cost effective solution for a patient, that does not make it the right solution for every customer especially when getting into higher prescriptions. Cost does not enter my mind when helping a customer pick out frames or their lenses unless they make it known that cost is an issue.

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## lensmanmd

> The majority of what you state I agree with. I don't think anyone was calling the 1.67 a miracle material and while it may not be much better in terms of it's ABBE value, I have never gotten complaints against 1.67 with regards to visual issues like I've received with Polycarbonate. While CR-39 and Polycarbonate may be the most cost effective solution for a patient, that does not make it the right solution for every customer especially when getting into higher prescriptions. Cost does not enter my mind when helping a customer pick out frames or their lenses unless they make it known that cost is an issue.


Thank you.  
Too many “opticians” only see higher indices and expect them to be better, with zero to little knowledge of the actual properties of the material.  
High index means I can sell a bigger frame.  No. I see this everyday.  
Understanding the pros and cons of every material, every frame/lens combo is all I’m asking.

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## pneese

> Thank you.  
> Too many opticians only see higher indices and expect them to be better, with zero to little knowledge of the actual properties of the material.  
> High index means I can sell a bigger frame.  No. I see this everyday.  
> Understanding the pros and cons of every material, every frame/lens combo is all Im asking.


Absolutely, it's our job to delve deeper into the needs of the customer to ensure a proper fit, etc. I do my best to make sure a customer's frame does not have too much decentration even with a 1.67 because thick lenses are still thick.

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## jefe

> I will less than respectfully disagree.  Whoever is selling that information is either clueless or full of sh*t.  Poly has its place, and is the best choice in a few, select situations.  Nine times out of ten it is absolutely not the BEST choice.  But, if you want your clientele to become frustrated when their lenses chip and crack, please use poly.  They will then become your former clientele.


+1

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## vfpamp

> But, if you want your clientele to become frustrated when their lenses chip and crack, please use poly. They will then become your former clientele.

Classic mistake of associating a product with the business/service. If you sold the glasses and they chipped and the customer is blaming you or your business enough to not come back, you deserve to be out of business. It means you are providing no value customers. All the value is PERCEIVED to be in the product. If the product is bad, you are bad.  

IMHO That's a horrible way to run a retail establishment.

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## pneese

> > But, if you want your clientele to become frustrated when their lenses chip and crack, please use poly. They will then become your former clientele.
> 
> Classic mistake of associating a product with the business/service. If you sold the glasses and they chipped and the customer is blaming you or your business enough to not come back, you deserve to be out of business. It means you are providing no value customers. All the value is PERCEIVED to be in the product. If the product is bad, you are bad.  
> 
> IMHO That's a horrible way to run a retail establishment.


+1

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## Kwill212

> > But, if you want your clientele to become frustrated when their lenses chip and crack, please use poly. They will then become your former clientele.
> 
> Classic mistake of associating a product with the business/service. If you sold the glasses and they chipped and the customer is blaming you or your business enough to not come back, you deserve to be out of business. It means you are providing no value customers. All the value is PERCEIVED to be in the product. If the product is bad, you are bad.  
> 
> IMHO That's a horrible way to run a retail establishment.


Sounds like something someone who has never worked in retail would say. The vast majority of the general public doesn't care about the why, the how, or your "added value". Cost, product, convince, all rank higher to most people in a retail setting. This is coming from someone who owns a very small relationship, type of business. I imagine in a high volume retail setting it is even more skewed.

Further, as an optician or a as customer, I would 100% blame the optician for chipped lenses if they used a material they knew could chip or crack in my glasses when there were better options for the application available. I don't care how good my optician is as replacing chipped lenses. I do care that the optician is smart enough to make glasses with lenses that won't chip the first time.

Let's say you got new tires on your car. You get a flat 2 weeks later and the store replaces it at no charge. Great. 3 weeks later you get a flat on another tire. You go in understandably upset. You speak with the manger who informs you that they are sorry about these tires not working out for you, but they can be predisposed to blowing out on your type of vehicle. Then asks if you would like to get the type of tires that won't blowout on your type of vehicle. You would be ok with this? Are you joking? I would be justifiably irate.

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## vfpamp

> Sounds like something someone who has never worked in retail would say.


I worked 3 years in retail. Made many mistakes like these. I still do. I know exactly how hard this is. Not everyone can do. Very, very few can do it, effectively, all the time. 

Cost, product and convenience are all added values. And they are YOURS, not your product's. Pay attention to what you are saying. Added value is what they care the most. If not, you already lost. They will just buy online. They are talking to you because they think there is a chance YOU (not your products) might add value. They just need to confirm it. You can break their expectations by passing the value over to the product and suffer the consequences of that, or confirm by getting it to yourself. It's all a slight tweak on your language and how do you present yourself.

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## val

Amen to that !

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## lensmanmd

Seems we all have our go-to's and our biases, eh?  Here is a chart that I have been working on for my work group so that they can try to avoid biases, personal or professional. 
Yes, its true that there are some that are sensitive to CA.  Most are not.  It is not always the material.  It could be a combination of material, base curve, fit and/or physiology.  It could be surface aberrations or warpage.  Not just one or the other.

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## vfpamp

> Here is a chart that I have been working on for my work group so that they can try to avoid biases, personal or professional.


Biases are reinforced by the small set of suppliers opticians and labs tend to work with in a recurring basis. 

I like the simplicity of the table, but I am not sure how effective it is given the high variability of specs within multiple products of the same supplier. 

For instance, when phones are manufactured, each of them go through a sequence of tests to validate their assembly. But failing one of these tests doesn't mean that the phone is not working as designed. For instance, a few tests will indicate memory longevity. Phones that are A quality, have results that inform the memory will last at least 3 years. B, C, and D qualities will last less. One worse than the other. When you buy a phone at a promotion or a discounted price from the main manufacturer, you are getting the C and D phones. They are exactly the same brand and model, they will work as good a the A one, but will present issues sooner than the As and Bs. 

Obviously, no one tells the consumers which quality they are getting and most people don't even know there is an internal ranking system for phones. And virtually every electronic component. 

The same thing happens with lenses and frames. With in the same type, within the same supplier and the same product line, you can buy A quality or D quality. If you cry for discounts, they will give you the D (pun intended). And those variances are big enough to change the table you have. Maybe the lenses will chip sooner. Maybe the abbe values are not as good due to an extended dying process. Maybe mold was getting old and slightly warped. 

And that's yet another reason why opticians diverge so much in their statements here.

This practice is so interesting that some companies only buy Cs and Ds and fix them individually to resell as A-like or B-like.

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## Uilleann

The reality is simply this:  The VAST majority of patients can't tell ANY difference WHATSOEVER between the optics of poly or Trivex, or even CR-39, when even remotely competently fit in appropriate prescription ranges.  It's that simple.  And the amount of CA induced in each material is not mathematically or optically significant to rise to a level that approaches human perception.  The math doesn't lie.

If you prefer Trivex for other reasons, and you're able to stay in business with the margins it provides you - great!  You get a gold star.  If someone else can do exactly what you're doing in the patient's eyes with poly, or CR, or 1.56, or the lid from a take-out food container - great!  They're every bit as competent to the patient at the end of the dispense.  The tired old Coke vs Pepsi, Ford vs Chevy, America vs anyone else tropes are beyond tired.  Let's bury the endless misinformation in the past, where it belongs.

 :Rolleyes:

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## drk

I look at it this way:
1. Poly for everyone because of it's good features.  Groovy, thinner, lighter, impacty, UV.  A great base lens.
2. High index for those who are bad.  (That's really a small number.)  1.67 is not the pick, here, but it's super available so we go with it.  The optics are no better or worse than poly.
3. Low index for those who are optical snobs.  (That's really a small number.)  Trivex is here with CR39. 

Remember, all the bad stuff about poly is power dependent.  If you use poly right, the disadvantages disappear.

And don't forget, 1.5 CT poly with a FFSV is pretty dang cool.

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## vfpamp

> The reality is simply this:  The VAST majority of patients can't tell ANY difference WHATSOEVER between the optics of poly or Trivex, or even CR-39, when even remotely competently fit in appropriate prescription ranges.  It's that simple.  And the amount of CA induced in each material is not mathematically or optically significant to rise to a level that approaches human perception.  The math doesn't lie.


While I agree with you, and not only with patients, sometimes I can't tell the difference between them myself, I also understand that people will not see the difference *until the appropriate environment highlights their difference*. Chromatic aberration only truly matters in broadband high contrast situations. Until the patient sees, and gets used to the benefits on a good lens and then goes back to a poorer one, he will not know the difference. But once he goes up, he will not like going back. And sometimes it takes weeks for them to notice that they went backwards in quality. By that time, most opticians already computed that patient as one of the "happy ones".

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## Uilleann

Again, the scenario is impossible, with properly fit lenses.  If you're fitting high Rxs in poly, then sure, you get everything you deserve when the patient's wrath comes down.  But the reality is EVERY single lens material - including our old beloved glass - exhibits CA.  If a pt is *that* picky, a discussion of CLs is in order.  But to continue to beat the dead horse, as far as CA is concerned, when properly fit, in a reasonable SRx range, the amount of CA a given eye will experience in poly is literally below human perception.  It's in the math.  It's easy to show.

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## lensmanmd

> I look at it this way:
> 1. Poly for everyone because of it's good features.  Groovy, thinner, lighter, impacty, UV.  A great base lens.
> 2. High index for those who are bad.  (That's really a small number.)  1.67 is not the pick, here, but it's super available so we go with it.  The optics are no better or worse than poly.
> 3. Low index for those who are optical snobs.  (That's really a small number.)  Trivex is here with CR39. 
> 
> Remember, all the bad stuff about poly is power dependent.  If you use poly right, the disadvantages disappear.
> 
> And don't forget, 1.5 CT poly with a FFSV is pretty dang cool.


+1.  

Know your material pros and cons.  Fit the best frame for the RX.  Minimize decentration.  Add AR to deal with reflectivity.   Know your materials.

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## jefe

> Attachment 14591


   love it!

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## Barry Santini

Stronger hyperopic presbyopes are very sensitive and aware of the effects of low abbé.

B

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## Uncle Fester

Sphere's +3.00 and up = stronger hyperope Barry?

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## Uilleann

IF Abbe alone were the end all - be all of lens design, every patient would still be wearing glass.  Which of course, STILL exhibits CA as well.  Just to a slightly lesser degree.  Poly is no miracle lens, but as a material, it is unquestionably viable for a VAST number of prescription lenses.  But feel free to continue pushing Trivex as the only other option if it makes you feel better at the end of the day.  Peace!

 :Giggle:

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## Robert Martellaro

> Stronger hyperopic presbyopes are very sensitive and aware of the effects of low abbé.
> 
> B


Maybe due in part to magnification that decreases the apparent field of vision, forcing the eyes to rotate further to see objects away from the primary gaze, compared to emmetropes and myopes.




> Sphere's +3.00 and up


I switched many folks from CR39 to Poly when 28's, Execs, and 7x28's were introduced in the early 80's. The results were mixed, with more than a few non-adapts. One case in particular that I'll never forget was a +3ish 7x28 wearer who rejected poly due to blurred text when reading. When I measured the add power the mires were very blurry, but became clearer as I moved the target towards the OC. I had no clue, except to switch back to CR39. That single case drove me to research aberration in lens systems, realizing that many of these lens material failures were due to chromatic aberration, sometimes aggravated by oblique astigmatism.  

Twenty years later I advanced to a +1.75 add after spending some time as an emerging presbyope, and acquired my 1st pair of computer eyeglasses. Being a -4.00 myope, I ordered -3.00 SV. I had been using Spectralite (Sola/Abbe 47 density 1.21 grams/cm3) at the time, but the lab said they had Poly with a good AR in stock, to save a few bucks and time I took the Poly. They worked fine, except that I noticed slightly blurred text at the edge of the screen. The base curve relationship was proper, I attributed the blur to CA. Although not good enough for a radiologist, I could grin and bear it. That was the last Poly lens I wore.

So yes, about three diopters of focal power or prismatic power (assuming all the other parameters are optimal), the latter also affecting the vision in the primary gaze, where it's generally accepted that the average threshold value of Lateral or Trans Chromatic Aberration is .1∆. Use the formula TCA=P/A where P is the prismatic effect at the oblique visual point on the lens, and A is the Abbe value of the material used. Use Prentice's rule to determine the value for prism.

Best regards,

Robert Martellaro

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## Lensman11

The abbe value of Trivex is the same as the abbe value of the human eye. There is no better material for eliminating Ca  why is Prentice rule a rule and not a law.

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## vfpamp

> The abbe value of Trivex is the same as the abbe value of the human eye. There is no better material for eliminating Ca  why is Prentice rule a rule and not a law.


I am a little rusty on this one but don't Abbe's add each other in some way? If you have chromatic aberration in one lens, a space, and the same chromatic error in another, in the end, you will have double chromatic aberration attenuated by the space between them.

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## lensmanmd

> The abbe value of Trivex is the same as the abbe value of the human eye. There is no better material for eliminating Ca  why is Prentice rule a rule and not a law.


Human eyes can not detect the chromatic aberration if the Abbe number is  above 40.  With that in mind, why not 1.6 for +3 and up, or -4 and up?   Yes, it is less impact resistant and weighs about CR39, but beyond  that, it is thinner, has high tensile strength so it is good for 3 piece  and nylor, and the ABBE is 42 vs 44.

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## AngeHamm

> Human eyes can not detect the chromatic aberration if the Abbe number is  above 40.  With that in mind, why not 1.6 for +3 and up, or -4 and up?   Yes, it is less impact resistant and weighs about CR39, but beyond  that, it is thinner, has high tensile strength so it is good for 3 piece  and nylor, and the ABBE is 42 vs 44.


I love 1.60. Love love love it. But it doesn't come in very many PAL, photochromic, stock, or polarized options, so its place in my dispensary is extremely limited.

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## drk

> I am a little rusty on this one but don't Abbe's add each other in some way? If you have chromatic aberration in one lens, a space, and the same chromatic error in another, in the end, you will have double chromatic aberration attenuated by the space between them.


That sounds right to me, but I never thought about that.

I do know that there is such a thing as an "apochromatic doublet" that somehow does a reversal of one lens' chromatic aberration for a pure outcome.  So what you say makes sense.

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## Robert Martellaro

> The abbe value of Trivex is the same as the abbe value of the human eye. There is no better material for eliminating Ca  why is Prentice rule a rule and not a law.


Because our eyes suffer from a high degree of axial/longitudinal chromatic aberration, we don't notice it in ophthalmic lenses. Instead, they are affected by transverse/lateral CA.

WRT rule or law, I'd throw in postulates and principles, choose one, and call it a day.

Best regards,

Robert Martellaro

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## Kwill212

> I love 1.60. Love love love it. But it doesn't come in very many PAL, photochromic, stock, or polarized options, so its place in my dispensary is extremely limited.


Maybe is the lens styles I use, but I have never had an availability issue in 1.60.

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## Uilleann

> ...I do know that there is such a thing as an "apochromatic doublet" that somehow does a reversal of one lens' chromatic aberration for a pure outcome.  So what you say makes sense.


It works in refracting telescopes, and some camera lens types - but I don't believe the tolerances required hold up to offer any real optical advantage with spectacle lenses, and mobile human eyeballs.

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## Canche

> Atoric and aspheric backside freeform processing has reduced the off axis aberrations.  STP processing using the turning tip has eliminated the lap/pad compensation and heat induced aberrations from toric surfacing, providing cleaner finished optics, but I wouldn't put Poly at the top of lens pyramid.  
> 
> Poly has improved over the past 3 decades.  Processing has improved.  COGs and profitability are awesome for the labs.  Still, there are better materials on the market.


what is the meaning of STP? 
Thanks

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## Barry Santini

> Because our eyes suffer from a high degree of axial/longitudinal chromatic aberration, we don't notice it in ophthalmic lenses. Instead, they are affected by transverse/lateral CA.
> 
> WRT rule or law, I'd throw in postulates and principles, choose one, and call it a day.
> 
> Best regards,
> 
> Robert Martellaro


True. But what’s often forgotten in the abbe-of-the-human-eyeball discussion is that the blue induced at the retinal plane from color error is always present—even if our eye has evolved to no longer notice it. So the eye’s effective threshold for noticing the blur induced by color error has been artificially (via evolution) elevated.

I believe this is one part of the reason why improper base curve choice, less than optimal lens design choice, and low material abbe can sum up and surpass this not-noticed threshold.

This is especially true for hyperopes wearing progressives and segmented lenses for reading.

B

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## jefe

> True. But whats often forgotten in the abbe-of-the-human-eyeball discussion is that the blue induced at the retinal plane from color error is always presenteven if our eye has evolved to no longer notice it. So the eyes effective threshold for noticing the blur induced by color error has been artificially (via evolution) elevated.
> 
> I believe this is one part of the reason why improper base curve choice, less than optimal lens design choice, and low material abbe can sum up and surpass this not-noticed threshold.
> 
> This is especially true for hyperopes wearing progressives and segmented lenses for reading.
> 
> B


For example, +3.00 sph. PALs in poly on a 4 base?

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## Barry Santini

Yup

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