Poly vs Trivex Question

[Jamelina]

Hello! Our opticians recently had a meeting with our lab manager. One of the topics was poly vs trivex. He (the lab manager) was going over how much better trivex is - abbe, scratch resistance, and impact resistance - compared to poly. He also stated that trivex is more impact resistant than poly. One of our doctors is hesitant when it comes to using trivex for anyone under 18 until there is more tangible evidence supporting that statement. So I started poking around different lens websites to see what I could find. Vision Ease has a page dedicated to this where it states that "Trivex claims to be as strong, or stronger than polycarbonate in impact resistance. This is not the case when the product is scratch coated or AR coated. According to Colts Laboratories, an abrasion resistant coating is going to be harder and more brittle than the lens in order to be abrasion resistant. This makes the lens easier to break due to that coating. The average coating reduces the strength 45% and the average AR coating reduces the strength another 20% for a total of 65%.".

I'm hoping to get some feedback/opinions from your experience, or other resources to explore, to discuss with our doctors. Thank you in advance for your help!!

[lensmanmd]

Hello! Our opticians recently had a meeting with our lab manager. One of the topics was poly vs trivex. He (the lab manager) was going over how much better trivex is - abbe, scratch resistance, and impact resistance - compared to poly. He also stated that trivex is more impact resistant than poly. One of our doctors is hesitant when it comes to using trivex for anyone under 18 until there is more tangible evidence supporting that statement. So I started poking around different lens websites to see what I could find. Vision Ease has a page dedicated to this where it states that "Trivex claims to be as strong, or stronger than polycarbonate in impact resistance. This is not the case when the product is scratch coated or AR coated. According to Colts Laboratories, an abrasion resistant coating is going to be harder and more brittle than the lens in order to be abrasion resistant. This makes the lens easier to break due to that coating. The average coating reduces the strength 45% and the average AR coating reduces the strength another 20% for a total of 65%.".

I'm hoping to get some feedback/opinions from your experience, or other resources to explore, to discuss with our doctors. Thank you in advance for your help!!

OK. I'll bite.

Your LM is correct in regards to optical clarity (*non FF processed) and scratch resistance as compared to Poly (based on factory FS coatings). The backside is the same across the board based on the hard coating used at the lab, and is a moot point, regardless of material. For dress wear, including AR, there should be no issues, even for Peds. Trivex is still far more impact resistant than CR39. Poly is more impact resistant when AR is applied, which is why we will not provide AR coated TVX in Sports goggles or Z-87/2 safety.

My in-house drop ball tests confirms that AR coated TVX @ 2.0mm fails close to 20% of the time. The same AR coated poly @ 2.0mm passes 100%. Both materials pass @ 100% without AR applied. As long as there is no AR, we will process 2.0mm safety thickness in TVX. Otherwise, we will stick to 3.0 for safety eyewear with AR on materials other than Poly.

With the improvements in FF processing, Poly performs very well in almost every RX range. Hi myopes and hyperopes will get better optics from 1.60 or 1.67. Those that are sensitive to CA would be good in TVX if weight is an issue, otherwise, a plain old CR39 will suffice for avg RXs. Personally, I see very little difference in my eyewear between Poly, CR39 and TVX. All are FF, BTW.

[Hayde]

The only thing I'd add to Lensman's superb post is Trivex' dramatic superiority over polycarb with respect to stress endurance--it avoids stress marks and stress fractures far better than poly. For general use, it's my lens material of choice. For kids and most other patients who can only expect a year or two out of their lenses anyway--poly is fine and usually cheaper.

[Jamelina]

Thank you both very much. That's exactly what I was looking for. Facts, facts, facts!

[Pete Hanlin]

Disclaimer- Essilor employee.

You might also find this white paper interesting (conclusion- in instances where impact resistance is paramount and AR is being applied, use polycarbonate).
https://www.ncbi.nlm.nih.gov/pubmed/16494611

As for the "optical benefits" claimed by Trivex, in the only actual wearer study I know of in which the two were directly compared more wearers actually preferred polycarbonate (but there was no statistically significant difference). The reasons were probably related to the fact that Trivex tends to be yellower than polycarbonate and has more haze (due to the molecular structure of the material).

As stated, the primary benefit of Trivex is it's insane tensile strength (resistance to tearing). For drill mounts, this means a Trivex lens will almost never fail- even if the lens is mounted rather poorly.

[Jamelina]

Excellent! Thank you!

Disclaimer- Essilor employee.

You might also find this white paper interesting (conclusion- in instances where impact resistance is paramount and AR is being applied, use polycarbonate).
https://www.ncbi.nlm.nih.gov/pubmed/16494611

As for the "optical benefits" claimed by Trivex, in the only actual wearer study I know of in which the two were directly compared more wearers actually preferred polycarbonate (but there was no statistically significant difference). The reasons were probably related to the fact that Trivex tends to be yellower than polycarbonate and has more haze (due to the molecular structure of the material).

As stated, the primary benefit of Trivex is it's insane tensile strength (resistance to tearing). For drill mounts, this means a Trivex lens will almost never fail- even if the lens is mounted rather poorly.

[Tallboy]

Thanks Pete and Lensman for your impact info on Trivex w/AR!

In my experience, which is anecdotal, there are far less coating failures with Trivex over Polycarbonate, mainly the ones related to chemical exposure seeping into the sides of poly lenses that then cause the hard coat to separate from the substrate and get the "peeling from the edges" phenomenon. This of course can very much be attributed to user error, take that as you will. Unfortunately I have to dispense to human beings, not robots.

I use trivex as my go to material for lightweight lenses for hyperopes and drill mounts, you can knife edge them and they will not crack over time like poly.

I also like 1.60 and poly a bunch, and 1.67 when its thinness outshines 1.60

[Quince]

My in-house drop ball tests confirms that AR coated TVX @ 2.0mm fails close to 20% of the time. The same AR coated poly @ 2.0mm passes 100%. Both materials pass @ 100% without AR applied. As long as there is no AR, we will process 2.0mm safety thickness in TVX. Otherwise, we will stick to 3.0 for safety eyewear with AR on materials other than Poly.

I just need to ask a clarifying question. The OP stated that even hard coat diminishes integrity- are your trivex lenses coated? Thank you for the wealth of knowledge pertaining to this matter. I'm passing this information along to my co-workers.

[lensmanmd]

I just need to ask a clarifying question. The OP stated that even hard coat diminishes integrity- are your trivex lenses coated? Thank you for the wealth of knowledge pertaining to this matter. I'm passing this information along to my co-workers.

Factory HC on front, spin on back. Uncoated scratches easily.

[lensmanmd]

Disclaimer- Essilor employee.

You might also find this white paper interesting (conclusion- in instances where impact resistance is paramount and AR is being applied, use polycarbonate).
https://www.ncbi.nlm.nih.gov/pubmed/16494611

Thanks for this, Pete. Would you happen to have a link to any white papers referencing Z87-2 testing on Trivex?

Nevermind. Z87.1-2003 is the most updated impact standard. Z87.1-2010 covers other properties, but not the impact resistance. Z87.1-2015, I believe was put into place in November 2016 with a 6 month grace period, with a few more modifications. Lack of sleep, my bad.

[Tallboy]

In all fairness pete thats your conclusion. The actual conclusion of that study was:

CONCLUSIONS:
We found that the mean impact resistance of the Phoenix lenses was greater than the level required of eye protector lenses by the standards AS/NZS 1337:1992, ANSI Z87.1-2003 and CSA Z94.3-02. Similar to CR39 and polycarbonate, the application of MAR to Phoenix lenses reduces their impact resistance, however, they provide an acceptable level of impact protection in industrial settings, where there is little danger of exposure to pointed or sharp-edged high-speed missiles.

[Chris Ryser]

Polycarbonate lenses will also turn milky white when coming into contact with the acids used in AR Strippers, the lens will become unusable.

If that is of interest to anybody, stay away from AR coating that material.

[Robert_S]

So if I intend to strip the AR coating off Polycarbonate, don't apply the AR coating. Got it. Thanks for the advice Chris!

[Uilleann]

How quickly we seem to forget the silly argument over the 'vastly superior' optics of Trivex vs poly...

https://www.2020mag.com/article/dear...color-my-world

https://www.2020mag.com/article/crossing-abbe-road

[Pete Hanlin]

Excellent article by Mike DiSanto- I miss him! I remember talking with him in an airport one time about how many practitioners avoid poly like the plague because of the "horrible abbe value" but just love to fit 1.67 high index (which has pretty much the same abbe value as poly). My favorite line of his was "When I first got into optics, the most popular material was... wood!"

For abbe value to become a factor in vision, you have to be looking through a portion of the lens that has a lot of prism- which means you're never going to notice abbe value near the optical center (and very few prescriptions have enough power to generate the peripheral prism needed to create significant differences in chromatic aberration).

[lensmanmd]

How quickly we seem to forget the silly argument over the 'vastly superior' optics of Trivex vs poly...

https://www.2020mag.com/article/dear...color-my-world

https://www.2020mag.com/article/crossing-abbe-road

And you trust 20/20? 20/20 is not as independent as you think.

TVX has its benefits, but I disagree with "vastly superior optics". Personally, I see very little difference (optically) between TVX and Poly. I am a presbyope, oblique with mixed astigmatism, which should speak volumes. Of course, all of my eyewear is Freeform and AR coated. I would agree that traditional Toric surfacing does provide an advantage with TVX, but with today's cleaner polymer, FF, or STP poly should not be dismissed.

Considering impact resistance, poly will certainly out weigh TVX any day of the week. There is also COGs to account for. TVX is great for net sales, but poly is a better fit your bottom line.

Weight and tensile strength gives TVX a big advantage over other materials, but @ 1.53, thickness can be an issue.

Just my 2 pennies.

[lensmanmd]

So if I intend to strip the AR coating off Polycarbonate, don't apply the AR coating. Got it. Thanks for the advice Chris!

You need to watch your times. Poly, when immersed in stripper over 1 minute, will turn milky and render it useless. I have found that the AR will strip cleanly around 30 seconds without damage. Any longer, even if it doesn't turn milky, the hardcoat can peel.

[Tallboy]

I definitely agree that more than any other optical material poly's success depends on quality of processing, namely surfacing and finishing. Stock poly FSV lenses (especially ar coated ones) seem to be the biggest culprits for strange areas of optical imperfection in the lenses. They look like blobs of non uniform dispersion of light in a polariscope. It is rare defect but I see it now and again usually after someone comes back complaining of a strange blurry spot off to the side of their lenses.

I definitely see crisper out of my 1.60 lenses but the pair i have on now are poly FF and I see well out of these too.

I dont think its necessarily just abbe though I think the monomer just makes a cleaner optical surface.

[lensmanmd]

Excellent article by Mike DiSanto- I miss him! I remember talking with him in an airport one time about how many practitioners avoid poly like the plague because of the "horrible abbe value" but just love to fit 1.67 high index (which has pretty much the same abbe value as poly). My favorite line of his was "When I first got into optics, the most popular material was... wood!"

For abbe value to become a factor in vision, you have to be looking through a portion of the lens that has a lot of prism- which means you're never going to notice abbe value near the optical center (and very few prescriptions have enough power to generate the peripheral prism needed to create significant differences in chromatic aberration).

And hence the difference between toric processing and Freeform processing. Thanks Pete.

[Chris Ryser]

You need to watch your times. Poly, when immersed in stripper over 1 minute, will turn milky and render it useless. I have found that the AR will strip cleanly around 30 seconds without damage. Any longer, even if it doesn't turn milky, the hardcoat can peel.

Some of the good hard coats are made with polysiloxanes which also will
dissolve in HF acid which is the main ingredient of AR strippers. They dissolve anything in the glass family.

[lensmanmd]

I definitely agree that more than any other optical material poly's success depends on quality of processing, namely surfacing and finishing. Stock poly FSV lenses (especially ar coated ones) seem to be the biggest culprits for strange areas of optical imperfection in the lenses. They look like blobs of non uniform dispersion of light in a polariscope. It is rare defect but I see it now and again usually after someone comes back complaining of a strange blurry spot off to the side of their lenses.

I definitely see crisper out of my 1.60 lenses but the pair i have on now are poly FF and I see well out of these too.

I dont think its necessarily just abbe though I think the monomer just makes a cleaner optical surface.

FSVAR suffers more from birefringence than any other anomaly. Another issue is the softness of poly. It is the most flexible of all materials, and sizing/shape matters. The polariscope will show stress on poly more than any other material. It is not always a go-to for troubleshooting.

Freeform poly is an amazing moneymaker for any practice, as long as you can get over the Abbe. Most of your patients won't notice a difference. It's time for us opticians to get over abbe values and personal prejudices.

[Tallboy]

FSVAR suffers more from birefringence than any other anomaly. Another issue is the softness of poly. It is the most flexible of all materials, and sizing/shape matters. The polariscope will show stress on poly more than any other material. It is not always a go-to for troubleshooting

I always try to cut poly (and all lenses) to show little or no stress at all, save for the occasional sunglass the all but requires it. For what its worth I wasn't talking about birefringence that is normal in the poly casting process, I'm talking about strange almost cotton looking blobs that are there and correspond to the exact area of the lens a patient is complaining about. I find them most often on FSVAR, Unity, Crizal and Somo. Its only happened about 4 times in 3 years but it happens. They are absolutely 100% invisible to the naked eye when inspecting the lenses. I've never seen them in surfaced poly of any kind.

[Uilleann]

And you trust 20/20? 20/20 is not as independent as you think.

TVX has its benefits, but I disagree with "vastly superior optics". Personally, I see very little difference (optically) between TVX and Poly. I am a presbyope, oblique with mixed astigmatism, which should speak volumes. Of course, all of my eyewear is Freeform and AR coated. I would agree that traditional Toric surfacing does provide an advantage with TVX, but with today's cleaner polymer, FF, or STP poly should not be dismissed.

Considering impact resistance, poly will certainly out weigh TVX any day of the week. There is also COGs to account for. TVX is great for net sales, but poly is a better fit your bottom line.

Weight and tensile strength gives TVX a big advantage over other materials, but @ 1.53, thickness can be an issue.

Just my 2 pennies.

Did you read the articles linked here? I believe we're generally much more in agreement than we're not. There is sound science in both articles, certainly not just marketing fluff pieces.

[lensmanmd]

Did you read the articles linked here? I believe we're generally much more in agreement than we're not. There is sound science in both articles, certainly not just marketing fluff pieces.

I just got a chance to read these. It's been a hectic week for us. I'm generally not a fan of the new 20/20, but these are older articles from 2009, when 20/20 had less focus on advertising frames.......I guess they focused more on optics instead of fashion back then?

When I first started in this industry, Glass and CR were king. Then Poly started to raise its ugly head, and we hated it. We had all of the necessary products and tools to process them, but the number of inclusions, or carbon specs, drove us crazy. And agreeing with the article, we had much more aberrations than CR, even with chilling the fining and polishing lines. This also coincided with the rise of PALs.....a crazy time for us lab rats. I was the surface manager at the time. Man, am I dating myself!

We have come a long, long way, for sure. Don't get me wrong, I do like Trivex, and I do everything that I can to position it as as a superior optical product in our locations, and have even updated our edging line to better handle the wear and tear that TVX creates. My biggest pet peeve with TVX is how and when our opticians sell TVX. Seldom do we see 3 piece, t-mounts, or even nylor in TVX. Instead, they promote 1.67 in lower RXs and TVX in higher RXs because they wrap their heads around the ABBE. Then, they complain about the weight of the 1.67 or the thickness of TVX. And don't get me started on the remakes due to cracking. I even created a Good-Better-Best for our centers and placed TVX as the lightest and clearest lens for low to mid-range RXs. I even went as far as to create a cheat sheet regarding the specific gravity of TVX vs 1.67. Yeah, imagine me shaking my head.

As I like to say, I'm just a lab manager, what do I know?

Back to what you said, yes, we are more in agreement than not.

My role in my organization is to create the best value for our patients, and at the same time, keep our COGs to an absolute minimum. We are a union organization, so labor costs are what they are. Perhaps, you can understand why I tend to side with Poly. The margins with Poly is so much better than Trivex.

Our FF platform provides the best of both worlds, and I am proud to say that over 99% of what we surface is either STP or FF. I have not used my toric line in over 3 months, and I have actually sold off all of my laps. Though the cost of diamonds can be daunting, compared to paying a union person to pull and restock laps, I'll gladly pay for re-lapping diamonds.

CA/VA issues rarely raise their ugly heads with Poly, and we actually have more remakes with TVX in regards to VA and patient satisfaction. Go figure.

[JF LDO]

I just got a chance to read these. It's been a hectic week for us. I'm generally not a fan of the new 20/20, but these are older articles from 2009, when 20/20 had less focus on advertising frames.......I guess they focused more on optics instead of fashion back then?

When I first started in this industry, Glass and CR were king. Then Poly started to raise its ugly head, and we hated it. We had all of the necessary products and tools to process them, but the number of inclusions, or carbon specs, drove us crazy. And agreeing with the article, we had much more aberrations than CR, even with chilling the fining and polishing lines. This also coincided with the rise of PALs.....a crazy time for us lab rats. I was the surface manager at the time. Man, am I dating myself!

We have come a long, long way, for sure. Don't get me wrong, I do like Trivex, and I do everything that I can to position it as as a superior optical product in our locations, and have even updated our edging line to better handle the wear and tear that TVX creates. My biggest pet peeve with TVX is how and when our opticians sell TVX. Seldom do we see 3 piece, t-mounts, or even nylor in TVX. Instead, they promote 1.67 in lower RXs and TVX in higher RXs because they wrap their heads around the ABBE. Then, they complain about the weight of the 1.67 or the thickness of TVX. And don't get me started on the remakes due to cracking. I even created a Good-Better-Best for our centers and placed TVX as the lightest and clearest lens for low to mid-range RXs. I even went as far as to create a cheat sheet regarding the specific gravity of TVX vs 1.67. Yeah, imagine me shaking my head.

As I like to say, I'm just a lab manager, what do I know?

Back to what you said, yes, we are more in agreement than not.

My role in my organization is to create the best value for our patients, and at the same time, keep our COGs to an absolute minimum. We are a union organization, so labor costs are what they are. Perhaps, you can understand why I tend to side with Poly. The margins with Poly is so much better than Trivex.

Our FF platform provides the best of both worlds, and I am proud to say that over 99% of what we surface is either STP or FF. I have not used my toric line in over 3 months, and I have actually sold off all of my laps. Though the cost of diamonds can be daunting, compared to paying a union person to pull and restock laps, I'll gladly pay for re-lapping diamonds.

CA/VA issues rarely raise their ugly heads with Poly, and we actually have more remakes with TVX in regards to VA and patient satisfaction. Go figure.

I agree, Poly over Trivex any day. Trivex is trash to me; very soft so over time a 3 or 4 base curve lens will turn to a 6 or 7 and its so dense that its hard on the equipment and causes more heat which equals aberrated lenses. Plus have you ever tried polishing trivex... It will melt before it polishes. I actually prefer 1.60- its tensile strength is superior to trivex making it the perfect lens for drills. Plus if you get the MR-8 1.60 the abbe is 41 (trivex 45 or so) so optics are super clear and its so much thinner and easier to work with than trivex.

Just my opinion though.