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Thread: New thinking on progressive heights?

  1. #1
    What's up? drk's Avatar
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    New thinking on progressive heights?

    I admit that I have been lulled into looking only at the fitting height when judging whether a frame can be used for a progressive lens. I've noted that Pete H. (I believe) relates that a minimum of 13mm, I believe (?) for the distance portion of the lens is important to success as well.

    If so, simple math says that for a standard progressive, all frames with a B dimension of 30 or less are unacceptable.

    If you look at your inventory, you can figure out how many frames are progressive-friendly by this objective standard.

    If you want to include short corridor progressives, you could have a second category that are "short-corridor progressive-friendly", and this would include B's of about 27-30mm. (Looking at it this way, BTW, shows the relative rarity of need for a short-corridor progressive.)

    Of course, the last category would be "progressive unfriendly"!

    And, of course, just labeling a frame as "progressive-friendly" or "short-corridor-progressive-friendly" wouldn't absolve you of your responsibility to individually evaluate each person, as their "schnozz" would make the final decision!

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    Manuf. Lens Surface Treatments
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    Progressive measurements.......................

    I would suggest to look at each manufacturers technical description and drawings of the lens surfaces. Only then you will know how much clear, clean crisp vision you supply to you patient.

    In my opinion as said on prior occasions......................all Mickey Mouse frames are generally progressive unfriendly.

  3. #3
    What's up? drk's Avatar
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    What do you mean by "Mickey Mouse" frames?

    On the "sales floor" we need a quick and easy way to judge whether a frame is suitable for a progressive. Any advance preparation is helpful. Do you have a suggestion as to how to apply your advice to a "sales floor"-type situation?

    Thanks.

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    RETIRED JRS's Avatar
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    Why not include a designator in frame SKU (or tag) that is on your display frames. Something simple like 'A', 'B', 'C'.

    Where 'A' = suitable to any progressive design, 'B' = only short corridors, 'C' = not suitable.

    It's not a perfect solution, exceptions do exist, but it might assist your opticians or at least act as a beginning guide. Ultimately, they still need to assess the patient need/desire, the Rx itself (since not Rx's are suitable to some frames), and their own good judgement.
    J. R. Smith


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    Yes Sir...............................

    Quote Originally Posted by drk

    What do you mean by "Mickey Mouse" frames?

    Do you have a suggestion as to how to apply your advice to a "sales floor"-type situation?

    1) Copy the manufacturer's drawing of the lens with the shown parts as center, progressive parts and reading area on a rigid clear plastic film. If desired make a left and a right.

    2) Cut it to some universal shape and size.

    3) Mark the measurements on the chosen frame or sample with a grease pencil(as used in bowling alleys) so it can easily be removed and cleaned.

    4) Super impose the clear film with the lens characteristics on the frame by just holding it over your measuremnt markings, or if you want the parient to get the feel stick it on with removable cotch tape. Or you could trace the lens marking with the grease pencil on the minus side of the samples frame lenses.

    Et voila.............you got an easy and inexpensive demonstrator for yourself and or the patient.

    PS I call those little frames with no space to look through Mickey Mouse.......sorry about that.:cheers:

  6. #6
    What's up? drk's Avatar
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    Thanks for the tips, guys. Both are excellent. Thanks.

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    Master OptiBoarder Lee Prewitt's Avatar
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    drk,


    May I suggest that a little training goes a long way? Your opticians should be able to evaluate the lens for the frame by simply putting PD stick up and saying "This frame would not work well for you Mrs. Jones. May I suggest this one as an alternative" I see too many opticians that are afraid to tell a patient NO. Do so with confidence and show your professionalism. That would include an alternative choice as well.

    The other methods work well too but why rely on a method as each individual will be unique?
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  8. #8
    What's up? drk's Avatar
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    Thanks for your comment, Lee.

    My optician is pretty good, no doubt, especially in terms of measuring seg heights. I just like to overthink things, at times, and the concept of "B" dimension influencing the frame choice instead of the actual seg height itself is a little new for us, although I'm sure many opticians here think that way.

    We just weren't paying as much attention to their distance area as their near area, with the "minimal fitting height" thought process.

    I think with the "B-dimension" thought process in addition to the "minimal fitting height" thought process, we can do several more things:

    1. When purchasing frames, we can actually quantify (not just look and surmise) whether a frame will work for progressives, and we could code the frames for easier reference on the floor.

    2. Of course, we will provide better distance vision.

    3. We will be more cognizant of the need (albeit suprisingly small, if you consider that a short corridor only gives about 2-3 mm more leeway) for the short corridor progressive.

    Who knows? My motto: Dumb it down, baby, so a trained monkey (even me) can do it!

  9. #9
    One eye sees, the other feels OptiBoard Silver Supporter
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    Drk,

    I'am comfortable with a 9mm distance window with a 28mm B. That's my limit; less than 9 or 28 would not be comfortable for me.

    In general, after a rough adjustment of the trial frame, I just ask the client if their awareness of the lens boundaries feels limiting, or aggravating. I go larger until it feels acceptable. Once the clients tolerance has been determined, I pick a frame that would be acceptable for the PAL design that has been chosen that will maximize their quality of vision.

    Robert

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    Master OptiBoarder Lee Prewitt's Avatar
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    I can see the advantage of having a system to assist in frame buying and for those whom are not yet as experienced as others. Intuitively, if you are getting a seg of 14-16 for a shorty, your B is still in the range of 27-30mm. Unless the frame fits with the pupil going through the top bar!! Let us know how the system works. If you find a better overall selection, errors go down, tec.
    Lee Prewitt, ABOM
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    Direct: (630) 274-6136
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  11. #11
    Master OptiBoarder Texas Ranger's Avatar
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    I suppose I'm getting really old...my first thought in frame styling is to sit down with the pt. and discuss their rx and what lens designs are supportive of solving their visual problems, this is before we frame style. we haven't fit a 'short corridor' pal yet. I believe that you need between 11-13mm of distance rx area, depending on vertec distance, and that 18 is a minimum for hts. some folks have rx's with almost no distance rx, such as +.25-.25x90, and state that they will not be wear the glasses except for desk work, so could make up a sv near pair in the short b frames in low adds and maybe a intermediate over near pal in higher adds, they just look over the top rim for distance, and are much happier than trying to find a tiny near area...so, why not find out what the pt expects the glasses to do, and let them know it if you think whatever it is won't work, before you make them up...

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    Hey guys.. here's a question, don't short corridor progressives that fit in real squatted frames tend to be of a harder progressive lens design.. would a progressive with a minimum 15 fitting ht work well in a frame with a 50 + B measurement..? Won't too much peripheral induced astigmatism be introduced into the lens with a large frame??

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    Master OptiBoarder Darryl Meister's Avatar
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    Yes, short-corridor progressives must suffer certain optical compromises. The power must change more rapidly, which essentially exaggerates the inherent limitations of progressive optics (there are probably several threads around here discussing this).

    Generally, you don't need to use progressive lenses designed for minimum fitting heights significantly lower than the fitting height required for a particular frame. For instance, if a frame requires a fitting height of 23 mm, using a short-corridor progressive with a minimum fitting height of 13 mm would simply result in those unnecessary optical compromises, including smaller fields of view and poorer peripheral optics.
    Darryl J. Meister, ABOM

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    Blue Jumper Keep this in mind..............................

    Quote Originally Posted by Darryl Meister
    .................................... if a frame requires a fitting height of 23 mm, using a short-corridor progressive with a minimum fitting height of 13 mm would simply result in those unnecessary optical compromises, including smaller fields of view and poorer peripheral optics.
    Thank you Darryl..........................when the master speaks everybody should listen.

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    Minimum Fitting Heights

    It would be good to know other parameters, say "maximum" fitting height and/or
    "optimum" fitting height. I would be interested to know the corridor widths from MRP to the area of nominal add power.
    Nick

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    Master OptiBoarder Darryl Meister's Avatar
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    Quote Originally Posted by Chris
    when the master speaks everybody should listen
    That's what I keep trying to tell my kids.
    Darryl J. Meister, ABOM

  17. #17
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by Darryl Meister
    Generally, you don't need to use progressive lenses designed for minimum fitting heights significantly lower than the fitting height required for a particular frame.
    One example is when the client performs an average amount of close tasks. These folks will be more comfortable with a less "dynamic" lens that offers clearer distance peripheral vision. On the other hand, I have been using short corridor lenses whenever there are above average close tasks i.e. avid readers and office desk work, especially when the add power is above +1.75, resulting in a shorter reading depth that minimizes posturing and increases the vertical field at near.

    Regards,
    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.



  18. #18
    Master OptiBoarder Darryl Meister's Avatar
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    Quote Originally Posted by Robert
    One example is when the client performs an average amount of close tasks. These folks will be more comfortable with a less "dynamic" lens that offers clearer distance peripheral vision.
    I may not be following your first example, since short-corridor designs don't provide clearer distance peripheral vision. As for your patient with above average near demands, keep in mind that there are many progressive lens options available that are designed to provide generous near vision without the compromises of short-corridor optics. Furthermore, these designs can actually provide a larger field of near than most short-corridor designs. I think most manufacturers have really converged upon a balance between corridor length and performance in general purpose progressive lenses.

    While short-corridor designs will potentially increase the vertical field of near vision, they often do so at the expense of lateral near vision, which is arguably more important for reading tasks involving horizontal lines of text. Also keep in mind that short-corridor designs generally reduce the intermediate field as well, which is very often important to someone engaged in near demands, since he or she is most likely using a computer in conjunction with these near tasks.
    Darryl J. Meister, ABOM

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    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote:
    Originally Posted by Robert
    One example is when the client performs an average amount of close tasks. These folks will be more comfortable with a less "dynamic" lens that offers clearer distance peripheral vision.

    Actually, I'm agreeing with your statement below, by providing an example of when NOT to use a short corridor design PAL. I think we are mis-reading each others quotes.
    Generally, you don't need to use progressive lenses designed for minimum fitting heights significantly lower than the fitting height required for a particular frame. For instance, if a frame requires a fitting height of 23 mm, using a short-corridor progressive with a minimum fitting height of 13 mm would simply result in those unnecessary optical compromises, including smaller fields of view and poorer peripheral optics.
    However, being an avid reader and an advanced presbyope (-4.50 add +2.25), I have found that the short corridor designs (I switched to a Concise and XS two years ago after wearing the SolaMax) are *much* more comfortable than medium to long corridor designs for frequent near tasks because they solve one of the most aggravating design limitations of PALs, that being the need to tilt the head back to see the middle and top of the page, eye level monitors, very small print at any height, and looking at my clients eyes. No, they do not replace my computer specs, but I don't feel like I have to run back home when I forget to bring them to work.

    Regards,
    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.



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    Robert, are you still using that XS lens, or are you talking about a zeiss or something else above?
    (Maybe or maybe not your point regarding the relative comfort of short-corridor lenses compared to medium/long corridor designs for frequent reading somewhat depends on the manufacturer?)

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    Quote Originally Posted by Darryl Meister
    While short-corridor designs will potentially increase the vertical field of near vision, they often do so at the expense of lateral near vision, which is arguably more important for reading tasks involving horizontal lines of text.
    Darryl , I'm confused because my (mis?)understanding is that the Brevity lens design offers a wider near-vision field than does the gradal top?

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    Master OptiBoarder Darryl Meister's Avatar
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    I'm confused because my (mis?)understanding is that the Brevity lens design offers a wider near-vision field than does the gradal top?
    Zeiss Brevity does, indeed, provide a wide near zone. There are several designs on the market, however, that do not.
    Darryl J. Meister, ABOM

  23. #23
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    Quote Originally Posted by Darryl Meister
    Zeiss Brevity does, indeed, provide a wide near zone. There are several designs on the market, however, that do not.
    Thanks for clarifying that.
    Quote Originally Posted by Darryl Meister
    While short-corridor designs will potentially increase the vertical field of near vision, they often do so at the expense of lateral near vision, which is arguably more important for reading tasks involving horizontal lines of text. Also keep in mind that short-corridor designs generally reduce the intermediate field as well, which is very often important to someone engaged in near demands, since he or she is most likely using a computer in conjunction with these near tasks.
    Quote Originally Posted by Robert Martellaro
    I have found that the short corridor designs (I switched to a Concise and XS two years ago after wearing the SolaMax) are *much* more comfortable than medium to long corridor designs for frequent near tasks because they solve one of the most aggravating design limitations of PALs, that being the need to tilt the head back to see the middle and top of the page, eye level monitors, very small print at any height, and looking at my clients eyes. No, they do not replace my computer specs, but I don't feel like I have to run back home when I forget to bring them to work.
    Hmmm, some great comments that seemingly create a dilemma for a borderline case like mine for example:

    Given my fitting height of 18 in frames of 29-30 mm, in Zeiss would you folks probably try the Gradal Top (min 18) or the Brevity (min 16)??
    (I'm a first-time PALer, Rx -6 Add 1.5 moderate astigmatism, an avid reader & puter-user who also wants good distance vision and only one set of glasses :D)
    TIA for any thoughts :cheers:

  24. #24
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by SkiBunny
    Robert, are you still using that XS lens, or are you talking about a zeiss or something else above? (Maybe or maybe not your point regarding the relative comfort of short-corridor lenses compared to medium/long corridor designs for frequent reading somewhat depends on the manufacturer?)
    The differences between manufacturers are subtle and hard to differentiate unless evaluated side by side. What narrows the choice for me is the lens material, base curve availability, how flat the front curve is on low powers and plus powers, and free form/atoric availabilty.

    Given my fitting height of 18 in frames of 29-30 mm, in Zeiss would you folks probably try the Gradal Top (min 18) or the Brevity (min 16)??
    (I'm a first-time PALer, Rx -6 Add 1.5 moderate astigmatism, an avid reader & puter-user who also wants good distance vision and only one set of glasses :D)
    Dental surgeons should be aware of the need for safety glasses and splash protection.

    One lens design that should be on the table is an atoric free form design. Zeiss's Individual is one of the best. No reason to be thinking short corridor designs here because of the low power "add for reading" and being a first time PAL wearer.
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  25. #25
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    Quote Originally Posted by Robert Martellaro
    Dental surgeons should be aware of the need for safety glasses and splash protection.
    I see someone read my profile ... I'm no dentist I'm retired recently (involuntarily) and I wouldn't even have filled the occupation field in the form if it wasn't mandatory... so student would probably be more accurate (but unbelievable for an emerging presbyope :D), or even more accurate would be beach bum and "ski bunny" :bbg:
    Quote Originally Posted by Robert Martellaro
    One lens design that should be on the table is an atoric free form design. Zeiss's Individual is one of the best.
    In fact I asked my provider about the Individual pursuant to posts here by you and others... however my optician quickly & briefly dismissed this lens apparently because they don't dispense it.

    I'm in Canada and when I phoned Zeiss here at the number on their consumer brochure to inquire about the Zeiss individual, the Zeiss rep asked me, "Who told you about the Individual"... as if it didn't exist or something!

    So I'm thinking this lens isn't sold in Canada (product selections in canada are often limited because of the small market size).... Anyone know for sure??

    As the Individual apparently isn't available here, then perhaps I instead should consider the semi-free-form Rodenstock Multigressive II (about which I've read here) or the new Ipseo (when it becomes available here) ???

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