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Thread: Is The New Trivex Lenses Thinner Than Aspheric Poly And Hi 1.67?

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    OptiBoard Novice Florida Specs's Avatar
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    Is The New Trivex Lenses Thinner Than Aspheric Poly And Hi 1.67?

    IN LIGHT OF THE INTRODUCTION OF THE NEW LENS MATERIAL "TRIVEX", HOW DOES IT RATE IN THINNESS NEXT TO HI 1.67 AND ASPHERIC POLYCARBONATE IF EYESIZES WERE ON AVG OF 50MM AND THERE WAS LITTLE OR NO DECENTRATION INVOLVED.SHOULD THIS BE A LENS INTRODUCED YET AND IF SO TO WHAT PATIENTS.....?


    FLORIDA SPECS
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    From my understanding Trivex can be as thin as a 1.6; therefore, it is not as thin as Essilor's AS Airwear, but probably thinner than some poly's out there, and it is not as thin as a 1.67. The lens has been on the market for about two years now if I am correct. It is ideal for impact resistance and has a high abbe value. The higher abbe value means, in theory, that you get better vision out of it. It really depends on the RX and the person, but I have not had a problem with the lower abbe lenses. Many people have been using Trivex for drill mount because of its impact resistance and that it does not split as much as poly. The Trivex lens is also very light and has a very low density as it can almost float on water.

    In conclusion, the Trivex lens is a good lens, but does have some stiff competition with the higher quality poly's.

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    Master OptiBoarder keithbenjamin's Avatar
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    There have been a few questions lately about lens material "thinness" and some apparent gross misunderstandings about what makes a lens thin.

    AS Airwear is no thinner than any other aspheric poly and certainly not thinner than aspheric 1.60.

    Comparing two lenses of differing materials and all else being equal (i.e asphericity, center thickness, decentration, and effective radius or blank size) the only thing you need to look at to determine thickness is the index of refraction. In other words: trivex (1.53) is thicker than poly (1.59), poly is thicker than 1.60, 1.60 is thicker than 1.66, etc.

    Unfortunately, things are not always equal. The impact resistance of poly and trivex are such that they can be ground to a minimum CT of 1.0mm which is where, I suspect, some of the confusion is coming in. With a smaller allowable CT, it is possible that a thinner lens could be ground with poly or trivex than with higher index materials, depending on the Rx and frame.

    So to answer your question, generally speaking, aspheric trivex will be thicker than aspheric poly, which will be thicker than aspheric 1.67. Again though, the differences do depend largely on the Rx and frame.

    Trivex was introduced over 2 years ago and has a proven track record. I've been wearing it for almost as long. It has an impact resistance equivilent to poly and a specific gravity of 1.11g/cm3 making it the lightest material on the market. Trivex is arguably better opticaly than poly because of its Abbe value and manufacturing process and is certainly more suitable for drill mounting (Younger guarantees their Trilogy (Trivex) product for life against stress fractures and drill mount cracking).

    Here are some articles that may be helpful:

    http://www.laramyk.com/learn/Methods..._Thickness.pdf
    http://www.laramyk.com/learn/Trivex_...carbonate.html
    http://www.laramyk.com/learn/aspherics_1.html

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    OptiBoard Professional OptiBoard Silver Supporter RT's Avatar
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    Just a couple of points relative to Keith's excellent response:

    1. Just because poly CAN be ground to a 1.0 mm CT, doesn't mean that it usually is. Most labs have either a 1.3 or 1.5 mm standard CT for poly, and charge extra to grind thinner. In a study of one lab, it turned out that approximately 10% of all poly Rx's were actually ground to a 1.0 mm CT.

    2. For powers up to about a -5.00 for a 50 eye and no decentration, the difference in thickness between Trivex and Poly is negligible. The difference primarily depends upon what the relative center thickness standards are for each material from your lab. In other words, from Lab A, Trivex may be thinner, and from Lab B, poly may be thinner.

    3. Trivex is an obvious choice for patients whose requirements include impact resistance, good optics, light weight, superior chemical resistance, and superior drillability. Trivex has been used successfully as a replacement for CR39, mid-index, polycarbonate, and polyurethane-based 1.60 (min center thickness 1.5 mm). Just because Trivex has impact resistance similar to poly doesn't mean that you have to pigeonhole it as merely a poly replacement.
    RT

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    Well I am from Canada and we do not have the same thickness requirements. What I do know is that I have used As Airwear with some customers and then had a problem with the lens so I switch them to TL 1.6 and the As Airwear is thinner, but not by a lot (I have checked CT and so forth). I also know that I have a pair or lenses with Trivex and with Airwear for myself (-5.50, -5.75) and the Airwear is much thinner. When I said that As Airwear is thinner than some poly's, I was refering to non-aspheric and cheaper poly's.

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    Master OptiBoarder keithbenjamin's Avatar
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    Good points RT, our lab routinely grinds to minimum CT (or customer spec) upon request. I tend to forget many labs don't do this.

    Keith

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    Trivex and AR Coating

    A word of caution....adding AR coating to Trivex significantly decreases its impact resistance. Younger recommends not adding AR coating to Trivex lenses used in prescription safety glasses.

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    ATO Member HarryChiling's Avatar
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    Quote Originally Posted by safetyguy
    A word of caution....adding AR coating to Trivex significantly decreases its impact resistance. Younger recommends not adding AR coating to Trivex lenses used in prescription safety glasses.
    AR coating reduces the impact resistance of any material.

    Quote Originally Posted by For-Life
    What I do know is that I have used As Airwear with some customers and then had a problem with the lens so I switch them to TL 1.6
    I have been having issues lately with the Asph Airwears. The airwear seems to be cacking, sometimes right in half. I have notied that in most cases it has been with patients cleaning with isopropyl alcohol, and I tried in the lab and that seems to be part of the issue, but I noticed that other poly lenses have not suffered from the same issue. For now have been changing all patinets to TL 1.6 as well.
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    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by HarryChiling View Post
    I have been having issues lately with the Asph Airwears. The airwear seems to be cacking, sometimes right in half. I have notied that in most cases it has been with patients cleaning with isopropyl alcohol, and I tried in the lab and that seems to be part of the issue, but I noticed that other poly lenses have not suffered from the same issue. For now have been changing all patinets to TL 1.6 as well.
    Funny...I'm not having *any* of these problems (except drill cracking) with Poly...AS or not.

    ???

    Barry

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    Quote Originally Posted by HarryChiling View Post
    AR coating reduces the impact resistance of any material.
    This is true. However, in the case of prescription safety glasses for High Impact (vs. Basic Impact), the addition of AR Coating made the difference, according to Younger, between passing High Impact and not passing High Impact.

    High Impact Testing is separated into three tests; High Mass, High Velocity and Penetration (needle test). To pass High Impact, the product must pass all three tests.

    According to third party tests, 2.0 mm Poly with AR Coating and Scratch Resistant back-side coating passes High Impact consistently. Trivex with AR Coating and Scratch Resistant back-side coating will pass the High Mass test (even at 1.0mm CT), but fails the High Velocity test at 2.0mm CT.

    Younger Optics' tests have shown that Trivex will pass High Impact at 2.0mm without any coatings. There is a very informative test summary on their website that's worth reading:

    http://www.youngeroptics.com/files/StraightTalk.pdf

    I am not aware of any other test results that are publicly available to confirm Younger's findings, but I consider them a trusted source.

    One thing to note regarding Younger's High Mass test. The following is an excerpt:

    "At very high energy levels (50 to 70x FDA), and for a -2D Rx and a nominal center thickness of 1 mm, the missile will bounce off of Trilogy, but will drive the Polycarbonate lens through its holder by turning it inside out."

    This is known as the "oil can effect", and would be considered a failure, however ANSI Z87.1-2003 requires a minimum center thickness of 2.0mm, regardless of lens material. Tests have shown that polycarbonate consistently passes High Impact at 2.0mm with AR and back-side coating, when lenses are manufactured according to ANSI Z87.1-2003 (properly surfaced, edged and mounted in Z87-2 frames).

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    One eye sees, the other feels. OptiBoard Gold Supporter
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    Quote Originally Posted by Florida Specs View Post
    IN LIGHT OF THE INTRODUCTION OF THE NEW LENS MATERIAL "TRIVEX", HOW DOES IT RATE IN THINNESS NEXT TO HI 1.67 AND ASPHERIC POLYCARBONATE IF EYESIZES WERE ON AVG OF 50MM AND THERE WAS LITTLE OR NO DECENTRATION INVOLVED.SHOULD THIS BE A LENS INTRODUCED YET AND IF SO TO WHAT PATIENTS.....?


    FLORIDA SPECS
    Due to index of refraction alone, the ratio between indexes gives a fairly accurate result- here's Trivex and Poly... (1.53 - 1.00) / (1.586 - 1.00) = .90 or about 10% thinner. 1.67 is about 20% thinner than Trivex.

    Your posts will be easier to read if you ease up on the caps key.

    Hope this helps
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    ATO Member HarryChiling's Avatar
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    I get my poly's consistently at a 1.5CT and I get the trivex at a 1.0CT (specified) so the difference in thickness ignoring the index is 0.5mm

    If you were to set a thickness formula for both trivex and poly equal to each other and then set you parameters for diameter to 50mm and the CTpoly=1.5mm and CTtrivex=1.0mm with the npoly=1.589 and ntrivex=1.53 you would get:

    (D*(d/2)2)/2000(npoly-1) + CTpoly = (D*(d/2)2)/2000(ntrivex-1) + CTtrivex

    (D*(50/2)2)/2000(1.586-1) + 1.5 = (D*(50/2)2)/2000(1.53-1) + 1.0
    [D*625/2000(0.586)] +1.5 = [D*625/2000(0.53) + 1.0
    0.5333*D + 1.5 = 0.5896*D + 1.00
    0.056*D=0.5
    D=8.93 (9.00)

    So for the thickness to make a difference poly would have to be ground to the same index as the trivex or if the difference in the CT on a minus is 0.5mm than the Rx would have to be over -9.50D for the poly to be thinner than the trivex. Trivex is going to be slightly thinner because it can be ground thinner in lower powers, but if you add in aspherics and such the rules of the game change. Just make sure to specify 1.0CT for you rpolys and they will be thinner than the trivex.
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    Has anyone found the field of vision to be less in Trivex progressives than other lens forms?

    Chip

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    Trivex is a lower index than poly. Therefore if groung the same ct poly will always be thinner.

    Your sales rep lied. Trivex IS thicker that lower index lenses. Trivex about the same as glass.
    Last edited by hridgeway; 01-10-2008 at 11:39 PM.

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    Master OptiBoarder OptiBoard Gold Supporter DragonLensmanWV's Avatar
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    Quote Originally Posted by chip anderson View Post
    Has anyone found the field of vision to be less in Trivex progressives than other lens forms?

    Chip

    I would think that would have more to do with the lens design that the material. I would guess an Image in Trivex would be comparable to an Image in Poly or CR-39.
    I know I can't wear a 1.67, and the 1.70 is better for me,but as bad as the 1.67 at only the blue end of the spectrum.
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    It's true, someone says trivex is good in drilling and mounting but when it comes to the thickness...ofcourse AS Airwear is better,though both is impact resistant. Sometimes it really matters the frame size to get a nice thickness. Trivex index is only 1.53 while Airwear is 1.59.

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    OptiWizard BMH's Avatar
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    Welcome to Optiboard Reylynn!

    Just thought I'd point out that you revived a thread almost 2 years old. The date is right above the users name. Last post was 10-2007.

    I used to do it too.

    :cheers:
    Properly medicated for your protection.

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    Trilogy Monograph

    Those of you interested in this link, might find this Monograph interesting on the Younger Website:

    www.youngeroptics.com/pdf/trilogy/Trilogy_Monograph.pdf

    Or go to the Trilogy Section of the Younger Website.

    In this monograph Ed Degenero compares Trivex, Poly, 1.67. for Thickness, Weight, and other factors, depending on the Rx.

    It's really an excellent Monograph and is well worth the time spent reading!

    Dave Rips
    Younger Optics

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    Underemployed Genius Jacqui's Avatar
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    Thanks Dave

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    Quote Originally Posted by CEO View Post
    Those of you interested in this link, might find this Monograph interesting on the Younger Website:

    www.youngeroptics.com/pdf/trilogy/Trilogy_Monograph.pdf

    Or go to the Trilogy Section of the Younger Website.

    In this monograph Ed Degenero compares Trivex, Poly, 1.67. for Thickness, Weight, and other factors, depending on the Rx.

    It's really an excellent Monograph and is well worth the time spent reading!

    Dave Rips
    Younger Optics
    Apples and oranges.

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