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Thread: Non adapt from comfort to physio???

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    Non adapt from comfort to physio???

    I have a patient who is complaining of limited distance with the new physios. He claims he can see better in the distance without the glasses which was not the case before and to get the best distance, he has to slide the glasses down literally so he is looking through the very top. RX: OD +1.50 -0.75 x 15 OS +1.75 -0.75 x 165 ADD: 2.00 Last pair was a quarter weaker for sphere and add power and comfort vs physio. I explained that he will be able to see better in the (far) distance vs close but again, he claimed this was not the case with the last pair. When I remeasured, his measurement should have been two higher??? this makes no sense to me. I truly don't feel that I can lower the fitting height and in fact, feel like I should raise it. Wouldn't this make the distance even worse if he feels like he needs to lower the frame to see better??? FYI my lab director weighed in on this and said that in plus prescriptions, it is actually weaker towards the top of PAL's so he might be seeking his old prescription but this is only a +.25 difference. I am leaning towards just changing back to the comforts and seg ht that is appropriate even if it is raised a little which seems counter intuitive.

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    I always mark plus Rx's a little higher, top of pupil, unless the patient wears them low. Have you dotted us his old set to see where his preferred height is?

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    Setting the distance marking too low would make it more difficult for the patient to reach the intermediate and near zones of the progressive. The only reason you would see a change in the distance powers by lowering the marks would be if the lens were cut high enough for the intermediate powers to be in front of the patient's distance line of sight.

    Given that, the patient lowering the frame to look through the top of the lens implies the lens was cut too high, not too low. Adding additional sphere and add power at the same time would exacerbate this effect. If the markings are measuring lower instead of higher, you need to check frame form and wear position, because that's the only other variable that would throw his powers off like you're describing. Keep in mind that by lowering the frame on his face, he's altering the vertex distance, too, which can also affect the Rx.

    Is Pete Hanlin the poster here that works for Essilor? If there's something I'm unaware of between the designs (likely) then he'd be the guy to ask.

    edit: check panto also, could be a major difference between the new frame and the old.
    Last edited by gaspoweredrobot; 12-06-2018 at 12:38 PM.

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    Quote Originally Posted by nellster View Post
    RX: OD +1.50 -0.75 x 15 OS +1.75 -0.75 x 165 ADD: 2.00 Last pair was a quarter weaker for sphere and add power and comfort vs physio.
    I see a lot of these, slight increase in plus for a mild hyperope and it causes blur at distance. I could delve into the physics here, but basically until the eyes adjust (in this case, relax) and allow the Rx to do the work, objects at extreme distances may appear "soft" or "blurry". It's a similar reason as to why myopes that have an increase in minus have to hold reading material much closer with a new Rx until the eyes adjust. As a matter of fact, this is exactly one point I discuss with all hyperopes who have an increase in plus before I sell them a new Rx.

    That being said, there are a few points that need some clarification to paint the whole picture.

    1.) How does the centration compare between his two pairs? If the old pair is intentionally fit lower, then you should do the same with his new pair.
    2.) Which design specifically is he using in his old pair, and what design specifically are you moving him to? This could make a drastic difference if he is using the traditional Comfort 2 and you're attempting to fit him into the newest Physio W3+.
    3.) What lens material is he using in his old pair? If his previous pair is CR-39 or Trivex and you're putting him in poly, the difference in abbe value can exacerbate the "soft" or "blurry" feeling.

    Don't get hung up on fitting height, make sure you look at all the variables.

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    sub specie aeternitatis Pete Hanlin's Avatar
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    A lot of good points have already been made. I agree with the main point all of the previous posts are driving towards:
    Whenever a previously happy wearer encounters an issue with a new pair, identify (and eliminate) all the variables (as bretk0923 mentioned).

    In this case, the variables are:
    1. Change in both distance and near Rx (slight increase of plus power).
    2. Change in fitting height (new pair is fit lower than previous pair).
    3. Change in progressive design (from a Varilux Comfort to a Varilux Physio).
    4. Change in lens material? (information not supplied)
    5. Change in frame? (information not supplied, but I'm guessing there may be a new frame, which raises additional possible variables...)
    6. Change in lens position (panto, wrap, vertex)?
    7. Change in prism thinning? (information not supplied)

    Okay, so let's discuss the variables:
    1. Rx change- any time you increase plus (or decrease minus), there is a real risk of non-adapt, because the eye cannot "accommodate the problem away." When a patient is "over-minused" (or under-plussed) by 0.25 at distance, the patient can usually overcome the refractive error with a little bit of accommodation. Young low-power hyperopes can get away without wearing correction at distance for this reason (although it comes back to bite them when they become presbyopes and need to get used to wearing correction for distance and near).
    In this case, the plus power has been increased- but only by 0.25. The +2.00 ADD tells us this patient still has some ability to accommodate- but the claim that he "sees better without his new glasses" is a bit mystifying (because he definitely isn't accommodating away +1.50D worth of uncorrected distance Rx).
    The easiest way to determine if the patient is being overplussed in his new glasses is to conduct (or have the doctor conduct) a duochrome test while wearing the new glasses. The duochrome is usually conducted with the LPED line on the chart- with two of the letters projected on a green background and the other two on a red background. Since red is ideally refracted slightly behind the retina and green slightly in front (assuming the distance Rx is spot on), the letters should look equally crisp. If the patient notices the new eyewear makes the letters in the red side to be crisper, try putting -0.25 (or even -0.50) trial lenses in front of the glasses. If the letters even out, the glasses are giving the patient more plus power than he needs. (Obviously, the doctor should conduct this test, but in some offices I managed, I was permitted to conduct this test to avoid tying up chair time with rechecks... it's a good way to eliminate Rx as an issue regardless.)
    2. Change in fitting height. I know some will disagree, but the fitting cross should really be put right at center pupil- especially with Varilux designs. I don't care if the patient is 6'6" or 5'3", a myope or a hyperope, or a low or high ADD. Varilux lenses are designed to work best when they are fit properly (the reasons some opticians fiddle with fitting parameters on other lenses is worthy of an entire book). In this case, the patient is fit low- which usually does not impact distance vision- so we can probably move on to other variables (but regardless, I would recommend the remake- regardless of design- be fit with the FRP at pupil center).
    You can easily verify whether the fitting height is the guilty variable by adjusting the frames to fit 2mm higher (or simply have him raise the lenses 2mm). In fact, the patient reports he sees better by moving the lenses down so he is looking through the very top (which really makes me want to know what the duochrome test tells us), so I'm guessing moving the lenses up 2mm isn't going to help. This brings us to:
    6. Change in lens position. Gaspoweredrobot makes a great point- if the frame has changed, check the panto. Panto and wrap have a lot more influence on wearer perception (especially of progressive lenses) than most people think. Every 2 degrees of tilt effectively moves the perceived optical center by 1mm. The other thing to check is vertex. If the position of the lens has changed dramatically with the new frame, try to recreate the position the old frame held the lenses in. BTW, if a patient complains of reflections s/he didn't see before, lens position can be the culprit as well. I've had numerous patients complain about seeing dash lights or reading lamp reflections in new glasses (even with ARC) which was resolved by adjusting the panto and wrap.
    3. Change in design. If you're going to remake anyway and you want to go back to the old design just to eliminate one more variable, that is understandable- but the lens design is very unlikely to be causing this particular complaint. There's nothing in the distance portion of either design that should be causing this sort of symptom. Even though this particular case involves Varilux designs, I have found that- regardless of design- the PAL design is very, very, very rarely the true cause of a non-adapt. When fit properly, nearly ANY design should provide acceptable vision to most patients (of course, acceptable and exceptional are two different things :^). Anything that rises to the level of "I just cannot wear these" is almost always due to the fitment of the lenses or the Rx (with fitment being the guilty variable in 80%+ of cases).
    4. Change in lens material. This is so unlikely to be the issue, I wouldn't even consider it (although if the material did change and you want to eliminate one more variable, it is understandable to go back to the previous material). The powers involved in this case effectively eliminate abbe as being the culprit. Even if the old material was 1.50 (abbe of 59) and the new material is poly (with an abbe of 30) the difference in chromatic aberration is negligible in this lens. Even if the patient is looking 10mm away from the OC, the difference between the amount of chroma with 1.50 vs. poly is <0.03D... chroma is almost NEVER the issue.
    If the material is poly, it IS possible that poor surface quality is causing a problem. Polycarbonate is the most challenging material to surface and polish. It is unlikely (but possible) there is a center defect, worm, or insufficient polishing on the back surface (more likely to be found in a digitally processed lens vs. a traditionally processed lens). It is impossible to know how these lenses were surfaced, because many labs process "traditional" designs with digital generators (reaping the benefit of "cut to polish"). The only way to verify the surface quality is to use an arc lamp (which I have, and if need be would be happy to examine the lenses- but one of the other variables listed above are far more likely to be the issue).

    Hope this helps- and sorry for the length. Really curious to see how the duochrome test turns out with this patient, because it certainly seems like he is being over-plussed at distance. BTW, this doesn't necessarily mean the refraction is incorrect- it is possible there is a warp in the lens (e.g., caused by overheated alloy- which can create a warp that runs around the circumference of the block). One way or another, however, the patient is likely seeing more plus than he wants.
    Last edited by Pete Hanlin; 12-06-2018 at 03:41 PM.
    Pete Hanlin, ABOM
    Sr. Director Professional Solutions
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    Quote Originally Posted by bretk0923 View Post
    I see a lot of these, slight increase in plus for a mild hyperope and it causes blur at distance. I could delve into the physics here, but basically until the eyes adjust (in this case, relax) and allow the Rx to do the work, objects at extreme distances may appear "soft" or "blurry". It's a similar reason as to why myopes that have an increase in minus have to hold reading material much closer with a new Rx until the eyes adjust. As a matter of fact, this is exactly one point I discuss with all hyperopes who have an increase in plus before I sell them a new Rx.
    I wish they would all discuss this! Drives me nuts when this happens. Sometimes as an optician, you don't have their old Rx so you don't know what kind of change they have. When the patients are warned of Rx adaptation, you have a better experience at dispensing!

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    He is coming in today and I thank you for your insights. I have had non adapts in the past from comforts to Varilux X and will never do that again. This being said, I have had success with comfort to basic physio so I don't really feel that this is the reason for the non -adapt. I truly feel that it is an rx issue but being just .25 is what has me so stumped. The Dr is going to refract again and we will see. I will raise the fitting height if needed even though it seems counter intuitive. I appreciate all the time you took to answer. my dr measures low and insists that I simply measured low but my intuition is telling me otherwise.

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    wow, thanks for the information. I often wonder if there is a wave in the lens and it is so hard for me to see defects or waves. My dr wont do the duochrome and simply wants to refract by placing a -.25 in distance and see if it helps. I was puzzled with this one because the lab rep always sold me on the physios claiming it is better in the overall optics esp distance than the comfort. He is coming in today and I really appreciate all this information. It has equipped me which is so important in this line of work. I am the only optician here and have never been one before.

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    Quote Originally Posted by nellster View Post
    My dr wont do the duochrome and simply wants to refract by placing a -.25 in distance and see if it helps.

    Does your Dr enjoy remakes? Red-Green testing is a super simple and a super fast way of starting the troubleshooting process, IMHO it should be done for every single patient at the end of their refraction. If the Rx isn't right there is nothing you as the optician can do to even start troubleshooting. Good luck to you. Sounds like you Dr is hanging you out to dry.

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    By the way, I did try to increase panto and give a wrap which didn't help but I didn't expect any success since panto raises the fitting height. I might be admitting my limitations in the training I received but in what cases should you increase panto for progressive wearers, or always???

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    I am trying to do the very best and getting educated and he thinks I am overthinking all of this. Yes a little frustrating. Thanks again for your information.

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    oops I meant he thinks I measured too high

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    Quote Originally Posted by nellster View Post
    By the way, I did try to increase panto and give a wrap which didn't help but I didn't expect any success since panto raises the fitting height. I might be admitting my limitations in the training I received but in what cases should you increase panto for progressive wearers, or always???
    Increasing pantoscopic tilt will lower the apparent fitting height from the patients perspective.

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    Quote Originally Posted by nellster View Post
    I was puzzled with this one because the lab rep always sold me on the physios claiming it is better in the overall optics esp distance than the comfort.
    Sounds like your sales rep did their job correctly, they sold you something that makes them more money.

    Quote Originally Posted by nellster View Post
    I am trying to do the very best and getting educated and he thinks I am overthinking all of this. Yes a little frustrating. Thanks again for your information.
    This is unfortunate to hear. I would hope that your doctor would support you in your quest to become the best optician you can be. Granted, there are times where investing too much time in a particular problem becomes less profitable for the company, and we can all understand that. If this is indeed a learning moment for you, then I would hope that you would have support to better serve patients in the future. But who am I to say one way or another?

    Quote Originally Posted by nellster View Post
    By the way, I did try to increase panto and give a wrap which didn't help but I didn't expect any success since panto raises the fitting height. I might be admitting my limitations in the training I received but in what cases should you increase panto for progressive wearers, or always???
    Kwill212 is correct. Increasing pantoscopic tilt lowers the perceived fitting height. You likely won't need to increase it for everyone, but you should definitely be aware of how more or less of it impacts the perceived optics of the lens. You can use a slight increase in tilt as a "quick fix" for someone who feels like they have to decline their head to see better at distance, but it doesn't always work. Customized progressive lenses that use position of wear measurements will take this into account, and thus you shouldn't have to make those types of adjustments.

    Ask your lab reps to send you some materials on position of wear measurements and how they impact the patient's perception of the prescription that is in the lenses if you are not familiar with that topic.

    Good luck! I hope you are able to help this patient!
    Last edited by bretk0923; 12-11-2018 at 06:58 PM. Reason: grammar

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    Just wanted to make one clarification. Varilux Physio does provide better optics to the patient compared to Varilux Comfort, because Varilux Physio has lower levels of higher order aberration along the umbilic (centerline of the progressive channel). Yes, I realize many practitioners (including some here) consider the application of wavefront-based technology to progressive design to be marketing huey, but the reduction in higher order aberrations (primarily coma) can be measured objectively (using an aberrometer) and the resultant increase in contrast sensitivity has also been measured subjectively (in multiple wearer studies).

    As everyone has discussed, there are many variables that may be having a greater impact than the design of the lens- the most important being the fitment of the lenses. The placement of the Fitting Reference Point along the optical axis of the eye is the single most important predictor of how the lens will function (not saying you have mis-fit the lens, just saying it is far and away the most important determinant of how a lens will function). If two different designs are each fit perfectly then yes, you can definitely show measurable differences in performance between designs over a population of patients. Even then, predicting the performance of a design for one specific patient is tricky. I can conduct a study to tell you which of two designs should be preferred by most patients- but it is a bit trickier to conduct a study to successfully predict what a specific patient will prefer unless I can identify a meaningful variable about that patient (btw, asking the patient which zone they use most often hasn't been demonstrated to be a meaningful variable for predicting what type of design s/he will prefer). This has been shown in multiple studies and in personal dispensing experience. If I conduct a study that shows- out of 40 wearers- 27 expressed a preference for Varilux Physio, 4 expressed a preference for Varilux Comfort, and 9 had no expressed preference, the study tells me Varilux Physio performs significantly better. That doesn't change the fact that 10% of the population (which may include this particular patient) prefers Varilux Comfort for reasons I may not be able to define.

    Best wishes with your patient, and it is too bad the duochrome isn't an option. If the doctor is convinced the Rx is appropriate, I would recommend eliminating every variable possible (same fit as before using the same design and material as before). Just be aware that- even then- the optical gods have ways of playing tricks on us... ah, the joys of being an optician!
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    Blue Jumper I would recommend the remake- regardless of design- .................................




    Quote Originally Posted by Pete Hanlin

    In this case, the patient is fit low- which usually does not impact distance vision- so we can probably move on to other variables (but regardless, I would recommend the remake- regardless of design- be fit with the FRP at pupil center).

    I just love Pete's way of explaining the facts.....................
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