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Thread: New progressive lens "welcomed"...........................

  1. #76
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    I love this discussion. It's so cool seeing in real time the questions and answers that come up with a new lens design. I have a couple questions of my own to add here.

    Quote Originally Posted by Pete Hanlin View Post
    Before the process is considered "complete," the studies will need to show substantial improvement in the targeted visual functions for ALL Rx categories (which means the Varilux X Series "design" will be quite different for a hyperope vs. a myope).
    Can you expand upon this? How is the design different from Rx to Rx? Perhaps more importantly, do we as opticians have functional control over which design is selected, or will "design A" always be chosen for a hyperope and "design B" always chosen for a myope? Do all of Varilux's lenses operate this way, or is this something that is unique to X-Series?

  2. #77
    sub specie aeternitatis Pete Hanlin's Avatar
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    Quote Originally Posted by bretk0923 View Post
    Can you expand upon this? How is the design different from Rx to Rx? Perhaps more importantly, do we as opticians have functional control over which design is selected, or will "design A" always be chosen for a hyperope and "design B" always chosen for a myope? Do all of Varilux's lenses operate this way, or is this something that is unique to X-Series?
    The simplest variable is related to prism. Consider a +4.00 sph hyperope vs. a -4.00 sph myope. Since the near zone extends to 8mm or so below the optical center (located at the PRP in a PAL), our hyperope is looking through up to 3.2 diopters of base up prism at near- which displaces the image and requires the eye to rotate downward an additional 1mm. Meanwhile, our myope is looking through base down prism, which displaces the image upward. Therefore, the vertical position of the eye will vary by as much as 2-3mm between myopes and hyperopes when reading. Likewise, the horizontal position of the eye will be vary (distance Rx has a small effect, and ADD power has a greater effect- since higher ADD powers have a shorter focal length which requires greater convergence). Every Varilux design since Varilux Panamic (launched in 2000) has featured varied progression length and inset based on ametropia and ADD. As long as the optician places the FRP (cross) right in front of center pupil, the near zone will be optimally placed to provide wearer satisfaction at near.

    Eye shape is another variable (since most myopia and hyperopia is related to axial length). Basically, myopic retinas are larger and myopes tend to have greater tolerance of steeper sphere slopes (rates of power change). This variable isn't as straight forward from a design perspective, because there are other factors that determine how tolerant a wearer will be to design "hardness" (e.g., does the patient use head movements or eye movements to view peripheral targets). There are other variables related to optical and physiological variables, but the above is one example of each.

    The key to everything is trial on real wearers- because the human visual system has a stubborn habit of being illogical. A great example of this occurred during the development of Varilux Ellipse. The general approach to short corridor PALs was "shorten the progression and maintain near area." Wearer studies showed this approach didn't necessarily deliver wearer satisfaction in smaller frames (the most important zone to maintain in a small frame is actually the distance zone, go figure).

    As for manually selecting design features, the LiveOptics concept is to "turn all the knobs, and test all the variations" during design development to determine the settings that result in the highest satisfaction for the most wearers. Not particularly satisfying (especially for someone like myself that likes to tinker with everything), but it's borne out by the data (e.g., analysis of a database containing over 500,000 orders, remakes are higher when progression length is manually selected vs. allowing the calculation to automatically set the progression length). A few years back, I was discussing this with a researcher from one of the Optometric programs, and he described a study where they found basically the same thing.

    Sorry for the length, and by no means am I an expert on the design process. The ladies and gentlemen who do this for a living can go on forever on the variables involved in progressive design (and they get pretty passionate about it). Hopefully this expands on the subject a bit, though.

    Best regards,
    Pete
    Pete Hanlin, ABOM
    Sr. Director Professional Solutions
    Essilor of America

  3. #78
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    Don't apologize about length at all! All of this is information that leads to a greater understanding, and I find it fascinating.

    I have to apologize to you, though, because I'm going to nitpick a little.

    I've long thought that this was the case with Varilux, in that the lab chooses the right design based on Rx, Add, frame size, materials, etc. Unfortunately, what I've found is that this causes a greater deal of difficulty in fitting those who do NOT fall into the optimal design characteristics set forth by Varilux.

    Say for instance that I have a +6.00 hyperope with a +2.50 add. On every patient I will measure both distance and near PDs, so let's say I only find an inset of 2mm total. Being a high hyperope, this patient is less tolerant to changes in oblique power errors, and Varilux predicts that she will have a greater convergence, so right off the bat I can predict with some pretty high accuracy that my patient will have problems here. Even choosing a harder lens design won't solve the problem, simply because I can't control the lens design's inset on this patient. Now let's compound the issue and say this patient had neck surgery and can't lift their head up very high. This would then facilitate the need for a much shorter corridor length. You can see where things spiral out of control pretty quickly.

    Of course this is only a theoretical example of someone who is a VERY unique case, but I've unfortunately run into this issue more times than with other lenses that allow me to have control over those parameters. Even minor visual behavior idiosyncrasies like a patient just simply not wanting to lift their head as high to get to the reading area become much more difficult to troubleshoot.

    Again, I apologize for nitpicking, but my underlying point is to see if there is a way that I can easily troubleshoot these issues while staying in the Varilux family. Be brutally honest, am I being unreasonable in hesitating with Varilux X until I can figure out how to fix these issues?
    Last edited by bretk0923; 12-02-2017 at 12:13 PM. Reason: grammar and typos

  4. #79
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    Quote Originally Posted by Pete Hanlin View Post
    Considering that design was launched back in 2000
    I thought Panamic was around in the mid and late 90s?

    At any rate, rule #1 of educating the public about the latest and greatest: Never mention Panamic (aka, one of very few lenses to actually be discontinued outright in the last 30 years due solely to poor performance).

    :)

    Just having a little fun!

  5. #80
    One eye sees, the other feels. OptiBoard Gold Supporter
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    Pete,

    Nice post. I would add that myopes see a smaller image (minification) that is compressed, slightly raising the near object, with a wider view. Hyperopes see a bigger image (magnification) lowering the near object, with a narrower view. Somewhat like putting a landscape picture on a balloon and adding or subtracting air to make it bigger or smaller.

    Quote Originally Posted by ThatOneGuy View Post
    I thought Panamic was around in the mid and late 90s?
    Comfort in 1993, Panamic in 2000, along with Individual Gradal Top and Sola Max.

    Best regards,

    Robert Martellaro
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  6. #81
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    Quote Originally Posted by Robert Martellaro View Post

    Comfort in 1993, Panamic in 2000, along with Individual Gradal Top and Sola Max.
    Thank you! The more decades go by, the harder it is for me to remember which decade what happened. :/

  7. #82
    One eye sees, the other feels. OptiBoard Gold Supporter
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    Quote Originally Posted by ThatOneGuy View Post
    Thank you! The more decades go by, the harder it is for me to remember which decade what happened. :/
    I hear you. When I try to remember when something occurred in the past, I always multiply the time by a factor of two.

    Best regards,

    Robert Martellaro
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    An expert is a man who has made all the mistakes which can be made, in a narrow field. -Niels Bohr

  8. #83
    sub specie aeternitatis Pete Hanlin's Avatar
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    I have to apologize to you, though, because I'm going to nitpick a little.
    No apology necessary. Around 95% of patients probably fall in the "average patient" category (in a normal distribution of patients). However, in a large practice that means you're going to see a "special" patient once every two days or so... Thank goodness for the special patients (they're the ones that allow a skilled optician to make her/his living :^).

    The lab chooses the right design based on Rx, Add, frame size, materials, etc.
    Minor point, but the lab doesn't choose the design. For most digital designs, the design files are set and stored within the lab's desktop, and the system simply picks the appropriate design. However for lenses such as Varilux X Series, the design is calculated on a remote supercomputer via a networked link. You are correct in that the calculation engine looks at the Rx, ADD, frame dimensions, fitting parameters, etc., and then calculates a design that is optimally suited.

    Say for instance that I have a +6.00 hyperope with a +2.50 add. On every patient I will measure both distance and near PDs, so let's say I only find an inset of 2mm total.
    Assuming you are measuring pupillary distance with a pupilometer, you have to also take into account the effects of prism. The patient may only converge 2mm from distance to near without correction- but the prismatic effect of their lenses will influence (in this case increase) their total convergence while wearing correction. Still, point taken- there are a few patients out there with special convergence requirements. (Sorry, now I'm nit-picking :^)

    Now let's compound the issue and say this patient had neck surgery and can't lift their head up very high.
    Actually, you CAN adjust the progression length of a Varilux W2+, W3+, S Series, or X Series progressive lens. We don't recommend or talk about it (although I guess I kinda am right now), but you can. One caveat- you need to be ordering through VisionWeb to a laboratory that is running the ELOA version of OptiFacts. There's a field that's necessary to inform the aforementioned calculation engine that the progression length optimization is being manually over-ridden (the calculation normally automatically adjusts the progression length to optimize intermediate and distance given the fitting height). Most laboratory management systems (LMS) don't have the field. However, we are working with the major players (e.g., DVI) to add the necessary field to make it possible for practitioners such as yourself to take control when you feel the need to do so. The reason most LMS do not have the field is most "variable corridor" products create individual datafiles for each progression length which are stored within the laboratory's computer as individual products. When a corridor is specified, the lab selects the product file for that particular corridor length. This doesn't work for Varilux X Series, because there are no "set" designs (the design for each lens is calculated individually based on the parameters mentioned earlier). One of the reasons we discourage manual selection of progression lengths comes from evaluation of an exceptionally large database of lab orders (which indicate jobs are more likely to be reordered when progression lengths are manually specified... this being across ALL progressive designs with manually variable corridors). However, for special situations where the practitioner really sees a need for specifying a particular length (usually shorter), the capability is there.

    My underlying point is to see if there is a way that I can easily troubleshoot these issues while staying in the Varilux family. Be brutally honest, am I being unreasonable in hesitating with Varilux X until I can figure out how to fix these issues?

    I am way too biased to answer this question (because of course I want you to start fitting Varilux X Series :^). Being as objective as possible, if you would like to give Varilux X Series a try, I think I would try it with that large % of patients who fall within the mythical "normal" category (who is really normal anyway :^). For the "special" patients, I would continue using the product you can tweak (after all, you might not use your sand wedge for every shot, but it's good to have it in the bag when you find yourself in sand).

    At any rate, rule #1 of educating the public about the latest and greatest: Never mention Panamic (aka, one of very few lenses to actually be discontinued outright in the last 30 years due solely to poor performance). Just having a little fun!
    Okay, I just have to say this... Varilux Panamic was an excellent design (I dispensed 1,000s of pairs back when I was still dispensing- mostly upconverting Varilux Comfort wearers). Varilux Panamic had a challenge that was specific to the US market (which was addressed during the development of Varilux Physio). My first presentation at Essilor (in 2002) was how to differentiate Varilux Panamic and Varilux Comfort (since this was the first time there were two Varilux designs :^), so Varilux Panamic has a special place in my heart!

    Nice post. I would add that myopes see a smaller image (minification) that is compressed, slightly raising the near object, with a wider view. Hyperopes see a bigger image (magnification) lowering the near object, with a narrower view. Somewhat like putting a landscape picture on a balloon and adding or subtracting air to make it bigger or smaller.
    Yes- great analogy. Along the same lines, the shape of the retina also varies between hyperopes and myopes (imagine projecting a powerpoint onto a screen where the screen has varying levels of concave curvature).
    Pete Hanlin, ABOM
    Sr. Director Professional Solutions
    Essilor of America

  9. #84
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    Wow, thanks a ton Pete, seriously. This is some really high-level info, and no Essilor or Varilux rep has ever volunteered to actually answer these questions for me.

    It's good to know more about HOW Varilux lenses are made (and designs chosen), because it gives me a better understanding of how the end product will function. Then, equipped with that understanding, I can deliver a higher success rate to my patients. I think after reading this that I am much more comfortable beginning to dispense Varilux X, knowing much better now where it should and should not work well.

    Thank you so much for taking the time to explain, this helps a ton.

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