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Thread: Freeform SV - quantifying the improvement

  1. #26
    Master OptiBoarder DanLiv's Avatar
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    Quote Originally Posted by Uilleann View Post
    In fairness, the exact same can just as easily be said for CR/glass.
    Quote Originally Posted by NAICITPO View Post
    Well yeah, if the person making the glasses doesn't understand basic optics they can make a bad pair of glasses regardless of the abbe value of the lens, right?
    Oh yes, true, I agree one can screw anything up easily. I was trying to explain why I believe polycarbonate is so (undeservedly) maligned in our industry. I believe it's the combination of 1) the prevalence of poly, 2) the desire for thin flat lenses, which pushed use of aspherics, and 3) the poorness of optical skill across our industry, specifically lack of understanding about aspheric design and fitting. Those three factors together mean there are a *a lot* of bad glasses being pumped out. When people look for a culprit in all the bad glasses, few opticians are going to blame their own lack of skill (it's not even really their fault, they are so woefully undertrained they don't even know that they don't know what they're doing.), and no retailers are going to abandon the cheap thin lenses making them profit hand-over-fist, so they wrongly blame the only thing left, the material.

  2. #27
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    Quote Originally Posted by DanLiv View Post
    Oh yes, true, I agree one can screw anything up easily. I was trying to explain why I believe polycarbonate is so (undeservedly) maligned in our industry. I believe it's the combination of 1) the prevalence of poly, 2) the desire for thin flat lenses, which pushed use of aspherics, and 3) the poorness of optical skill across our industry, specifically lack of understanding about aspheric design and fitting. Those three factors together mean there are a *a lot* of bad glasses being pumped out. When people look for a culprit in all the bad glasses, few opticians are going to blame their own lack of skill (it's not even really their fault, they are so woefully undertrained they don't even know that they don't know what they're doing.), and no retailers are going to abandon the cheap thin lenses making them profit hand-over-fist, so they wrongly blame the only thing left, the material.
    +1

  3. #28
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by NAICITPO View Post
    If you were to use the correct base curve and the frame was measured and fit by an experienced optician what's the difference the wearer is going to experience due to a 32 abbe for poly and a 45 for trivex? In my experience it hasn't been much.
    I think the first question to be answered is what is the wearer’s type of ametropia?

  4. #29
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    Well sure, higher diopters of power may change the experience but in general to say that everyone will notice the difference from 30 abbe to 45 is just not the case from what I've seen. There are people completely pooping on poly and acting like trivex is the savior of all things optics. From my understanding (and please correct me if I am wrong would love to learn) that under 2 diopters there is no discernable difference in optics to the person wearing the lens. Past 2 diopters people may notice a difference in colors at oblique angles. Usually past 4 diopters I start talking about 1.67. So between 2 and 4 diopters for people who are very particular about their vision like engineers, and we have more at our practice than we can shake a stick at, I will talk about trivex.

    I just love hearing that the abbe value of trivex is similar to that of CR39. Do you not understand math? The abbe value of trivex is almost as far away from CR39 as poly is from trivex.

  5. #30
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    The Abbe value of Trivex is almost the same as that of the human eye optical system so it should cause the least disruption to the normal way we see colors.

  6. #31
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    The Abbe value of Trivex is almost the same as that of the human eye optical system so it should cause the least disruption to the normal way we see colors.
    Oh boy. And if you believe this, I have a bridge….

  7. #32
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    Personally I don't see any difference with Trivex vs Poly. I have optical friends that can. It's a good material and I like it and use it a lot. I tell patients that some people can see a difference and some can't. I love the durability and mostly sell it for that. Lately I have seen some cracked poly which I suspect is from Covid cleaning. People cleaning with hand sanitizer and bad, bad things. So I switch who I can from poly to trivex since cost difference is minimal.

  8. #33
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    Barry
    what fact about Abbe values are you disputing.

  9. #34
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    Quote Originally Posted by Lensman11 View Post
    Barry
    what fact about Abbe values are you disputing.
    Maybe the difference in optics from the eye itself and a trivex lens being off the eye? Can't really dispute that the abbe value of the eye is approximately 45 and the abbe value of trivex is also approximately 45.

    Quote Originally Posted by Barry Santini View Post
    Oh boy. And if you believe this, I have a bridge….
    Tell me more about your bridge... I recently just paid a prince in Africa a small sum of money and he is going to give me back a billion dollars in January!

  10. #35
    One eye sees, the other feels. OptiBoard Silver Supporter
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    Quote Originally Posted by Lensman11 View Post
    The Abbe value of Trivex is almost the same as that of the human eye optical system so it should cause the least disruption to the normal way we see colors.
    Lensman,

    There are two types of chromatic aberration: Lateral or transverse, and axial or longitudinal. See...

    https://www.optiboard.com/forums/sho...ll=1#post44885

    And...

    https://www.optiboard.com/forums/sho...ll=1#post45680

    Best regards,

    Robert Martellaro
    Last edited by Robert Martellaro; 12-29-2021 at 08:54 PM.
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    ~~~~~~~~~~~~~~~~~~
    Science is a way of trying not to fool yourself. - Richard P. Feynman

    Experience is the hardest teacher. She gives the test before the lesson.



  11. #36
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    Quote Originally Posted by Robert Martellaro View Post
    Lensman,

    There's two types of chromatic aberration: Lateral or transverse, and axial or longitudinal. See...

    https://www.optiboard.com/forums/sho...ll=1#post44885

    And...

    https://www.optiboard.com/forums/sho...ll=1#post45680

    Best regards,

    Robert Martellaro
    Hall of Fame thread
    Last edited by NAICITPO; 12-29-2021 at 08:46 PM.

  12. #37
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    Barry
    what fact about Abbe values are you disputing.
    i dispute the apparent resonance that matching the abbe of a lens to that of the eye will bring.
    Someone please explain.

  13. #38
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    Did you ever get a complaint from a high index wearer that they don’t quite she as sharp with their lenses as they did with cr. Did you ever look thru an inexpensive microscope or binoculars and see color fringes. Those are not caused by off center viewing. Real feedback from patients have been that they see clearer thru Trivex. The majority of responses and reactions in this industry are not from any real science but from anecdotal patient responses. I can’t tell you how many times I have been asked to disregard good practice and make cosmetic appearance the primary factor. If the patient likes the way they look they except compromised vision.
    Dispense any material you like none will be 100% successful or 100% a failure. Satisfy your customer what ever the driver might be, but remember there is no one answer that works all the time.

  14. #39
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    Did you ever get a complaint from a high index wearer that they don’t quite she as sharp with their lenses as they did with cr. Did you ever look thru an inexpensive microscope or binoculars and see color fringes. Those are not caused by off center viewing. Real feedback from patients have been that they see clearer thru Trivex. The majority of responses and reactions in this industry are not from any real science but from anecdotal patient responses. I can’t tell you how many times I have been asked to disregard good practice and make cosmetic appearance the primary factor. If the patient likes the way they look they except compromised vision.
    Dispense any material you like none will be 100% successful or 100% a failure. Satisfy your customer what ever the driver might be, but remember there is no one answer that works all the time.
    When I receive such a complaint (and suspect a color error is the issue), the first thing I do is wear the glasses to verify the color complaint.

    And re: binoculars and color error, it is the objective’s fast F/3.5 f-ratio AND the wide angle eyepiece designs common to terrestrial binocs that are the offending culprits—not the “quality” of the glass.

    Barry
    Last edited by Barry Santini; 01-01-2022 at 04:16 PM.

  15. #40
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    Please explain how you putting on the patients glasses would have the same effect on you as it does on the patient. Lens materials are very consistent so you should have the same result with the same material every time you put them on but we do have the variable of the Rx and the pd not matching yours. Not having good acuity is not always a color problem from the material.

  16. #41
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    I too put on the glasses and usually see the complaint which makes it easy to know I need to fix the problem.

    That said, when I can not see the problem it lets me open a discussion with the patient over how the mystery of vision sometimes stumps the experts, and me.

    As well- sometimes the problem is between the patients ears;)
    Last edited by Uncle Fester; 01-02-2022 at 12:13 AM. Reason: tweak and I have no life....Happy New Year!!!

  17. #42
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    Please explain how you putting on the patients glasses would have the same effect on you as it does on the patient. Lens materials are very consistent so you should have the same result with the same material every time you put them on but we do have the variable of the Rx and the pd not matching yours. Not having good acuity is not always a color problem from the material.

    By PD do you mean prism…or just PD?

    Trying on the glasses will almost always let you see the differences. Try it!

    Barry

  18. #43
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    By pd I mean induced prism. This idea is most interesting what differences do you observe by trying on the patients glasses.

  19. #44
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    By pd I mean induced prism. This idea is most interesting what differences do you observe by trying on the patients glasses.
    You can always see if low abbe/color error is an acuity degrading factor.
    You can also compare corridor effects
    and you can see firsthand if tilt of wrap helps.

    barry

  20. #45
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    Barry
    This is a great source of information if you can see if a low Abbe value error is a degrading factor in any Rx you look thru. Have you kept data on the relationship between the material and the Rx and when this degradation takes place, it should be a constant that is predictable and avoidable. Did you ever have this experience of degradation of acuity with Trivex or Cr.

  21. #46
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Quote Originally Posted by Lensman11 View Post
    Barry
    This is a great source of information if you can see if a low Abbe value error is a degrading factor in any Rx you look thru. Have you kept data on the relationship between the material and the Rx and when this degradation takes place, it should be a constant that is predictable and avoidable. Did you ever have this experience of degradation of acuity with Trivex or Cr.
    The most surprising insight was something I feel I should’ve known beforehand:

    Hyperopic presby Rxs are far more impacted by the off axis effects of low abbe than myopic Rxs.

  22. #47
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    The thread name seems lacking for a Hall of Fame thread.
    While the original thread name will appear any suggestions for a short but succinct line or two of what this discussion is talking about besides Quantifying FF SV?

  23. #48
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    Quote Originally Posted by Uncle Fester View Post
    The thread name seems lacking for a Hall of Fame thread.
    Any suggestions for a short but succinct name of what this discussion is talking about besides Quantifying FF SV?
    I think the thread content seems lacking for a HOF thread...

  24. #49
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    Quote Originally Posted by Kwill212 View Post
    I think the thread content seems lacking for a HOF thread...
    Hee hee, I have to agree.

    Not that this is more than an opinion, but here it is:
    1. A very low number of people reject eyeglasses for chromatic aberration.
    2. I don't think it's valid to compare "the abbe of the eye system" to lens materials, just as a hunch.
    3. The difference between glass and CR39 and trivex is insignificant
    4. The difference between poly, 1.6, 1.67 is insignificant.
    5. All chromatic aberration is lens thickness dependent. When we have high power lenses, we virtually have to compromise optics for comfort and cosmetics. (I think this can be offset by a good free-form design, and is a good reason to use FF in higher-power lenses).
    6. I haven't seen a difference in chromatic aberration complaints between plus or minus patients.
    7. I don't feel that direct observation through a lens to trouble-shoot chromatic aberration is going to be sensitive and specific enough to be useful.
    8. People that do complain of chromatic aberration are just getting used to something new and different, and may be a visually sensitive-type of person. They'll get used to it, if they can keep the faith. (Which means: remake! in this day and age).
    9. I do feel that there is probably a barely-perceptable improvement in vision between lens indices in higher-power lenses. If you had to, for some reason, produce the "best vision evah" for a higher ametrope, you'd use a low-index material and do a free-form design (it'd better be SV, too), and put it in a 44 eyesize frame or something. Fortunately that doesn't happen in the real world.

  25. #50
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    I stick with my original statement that the information stated is anecdotal the comments made by some very informed and competent members of this board are contrary to each other. One states hyperopic presbyopes have more chromatic issues than myopes the other finds no difference. They are personal experiences not scientific data. One dispenser swears by a certain lens design and material and another swears at it.
    I worked for the largest non governmental health organization in the us and all medical decisions were data driven not not personal experience driven. Those decisions could and would change over time as the data evolves.
    The human eye is a lens system with different components having different indexes if you add another component to the system it is going to have an effect on the acuity of the patient. Some people learn to except the new visual experience others do not. Learn from your and other dispenser experiences but always remember the results will not be the same with everyone.

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