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Thread: Offset round seg complicated rx...freeform magic possible???

  1. #1
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    Offset round seg complicated rx...freeform magic possible???

    Guru's needed!

    Unique request from a motivated very sweet patient:

    R -1.00 -1.25 x 173 4^ out
    L 0.00 single vision 4^ out
    Add +1.75 right lens only

    She needs prism for distance but not near and has worn a ft28 right eye only successfully to suppress the diplopia but prefers less noticeable shelf and head turning.

    So she wants the right seg offset about 10mm to see dashboard GPS with minimal head turning.

    Can the OC's be manipulated to make this work?

    She is not cost averse to a custom Franklin which leaves me scratching my head as to a flat top shelf being noticeable- but whatever.

    And that begs the question is any lab out there doing Franklin's and am I correct that this can only be done with a metal frame?

  2. #2
    What's up? drk's Avatar
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    Jacqui was the Franklin queen. Is she still around?

    I know Three Rivers used to do a nice digital backside round seg, but I don't know if they can put the distance optics where you need them with a 10mm temporal decentration if they have standardized, inflexible software. It is an old design, but maybe updated? (That assumes there is a non-standardized, flexible software that can float the distance optics anywhere.)

    I will say, though, that if she's a binocular vision disaster, you may want to trial frame (including prism) that bad boy to see what happens to her fusion in that direction of gaze. There are conditions that require different prism in different directions of gaze (impossible to deliver, of course), so make sure this "eye turning vs. head turning" exercise doesn't lead to futility.
    Last edited by drk; 07-11-2022 at 12:11 PM.

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    Master OptiBoarder optical24/7's Avatar
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    Very similar to a golf seg placement with a rd seg. Very doable if you find a lab that know what a golf seg is and if familiar with the concept.

    *(Note: TMK, SF rd segs are only available in cr39, (Other than glass). Any other material will need a digitally produced lens like drk mentioned.)

    No diplopia near since she’s using these as mono vision near.

  4. #4
    What's up? drk's Avatar
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    Hey, O24.

    I'm reading it as "penalization" of the left eye at near.

    Which, with BO prism, is weird because that means she's an esotrope, and esotropes' little crossy-eye thing is not always bad, at near. We all have the little crossy-eye thing at near, as you are undoubtedly aware.

    One of the binocular vision esoterica factoids is the concept of "centration point" (I did NOT name that), where an esotrope actually is crossed the "right amount" at SOME NEAR DISTANCE (= centration point) in the fashion of "a stopped clock is right twice a day".

    At this possibly-existent "centration point" the otherwise crappy monocular vision blossoms into a beautiful stereoscopic view, causing almost enough emotion as a Enchroma commercial. (Just kidding.)

    But that centration point could be @ 50cm, 40cm or 2 cm. Sometimes usable, sometimes not.

    And not all esotropes have this. Probably the minority. Most are monocular. But, anyway, this patient is not a longstanding trope if she has diplopia, I'm guessing.

  5. #5
    Master OptiBoarder optical24/7's Avatar
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    Doc,

    My response was/is directed to the issues Fester posed. My take is:

    Patients 4D eso distance.
    Patient uses bifocal monocular.
    Patient wants outset on her seg rather than (traditional) inset, for near vision to use more eye movement to access the seg…

    All of this is easily accomplished with a lens made like golf segs:

    For those not familiar, back in ancient times, we made “golf segs” for patients wanting distance only sunglasses for golf, but needed some add/+ for close vision, checking their scorecard, ball divots, bar menu at the 19th hole, ect.

    On a lab level, we used rd segs and rather than inset the seg at layout, we turn the seg as far lower temporal as we could with the shape give for the particular frame. You then process it like a sv, given in reference to the seg location. Prism is no problem. Once you orient the seg to shape, it just like grinding a sv.

    Back to the OP, one of the main things I take from fester is she wants off center near vision. She’s using bifocals monocularly, hence, no diplopia at near, so outset it as much as she likes, she’ll just have to view all near objects from that same angle.

  6. #6
    OptiWizard
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    If I am understanding your request you do not want prism in the reading portion. That is not possible as the prism is on the entire lens whether a seg is present or not.

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    OptiBoardaholic OptiBoard Bronze Supporter
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    I had a Franklin done by Epic Labs last year and it came out pretty nice.

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    Master OptiBoarder optical24/7's Avatar
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    Prism does not matter ​ if they are using lenses monocular!

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    What's up? drk's Avatar
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    I think Fes is thinking Franklin so he can have the distance optics any way he wants, and move the seg where he wants. I think he wants prism in both areas.

    The OS is plano so that's 99% likely to be a "balance lens" concept and it probably has amblyopia in that eye, yet the prism is there for gross, peripheral fusion (or is "just there" for no functional purpose because the prescriber wanted to "do something".)

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    Master OptiBoarder optical24/7's Avatar
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    1. A Franklin lenses line is way more noticeable than a cast executive.

    2. If the Plano OS was a “balance” lens, she wouldn’t need prism distance ( unless it was to turn the eyes for cosmetics).

    3. She’s obviously using a bifocal monocularly since there’s only one (on the right eye), So any prism amount (induced or prescribed) in that one bifocal is mute.

    A rd seg is just like a sv lens. You can do powers and prism just like you would with a sv lens. The only issue in the above patients request is where to orient the seg. And a rd seg can fill all requests listed in the OP. (Less bifocal edge, wants seg outset, less head movement towards lower peripheral right, prism needed distance). Once again, any prism in the near area of the bifocal doesn’t matter because she’s not using them as a “bifocal”, she using them as a “monofocal”. You pretty much need 2 images to even have diplopia (other than certain medical issues like lens subluxation).

    I think this “problem” is being over analyzed. Hopefully Fester can chime in and clarify any issues we haven’t addressed.

  11. #11
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    She was in yesterday for an adjustment and the jury is still out. I may just need to redo the OD seg higher. Stay tuned and thanks for the posts!

  12. #12
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    Quote Originally Posted by optical24/7 View Post
    Prism does not matter ​ if they are using lenses monocular!
    Quote Originally Posted by optical24/7 View Post
    1. A Franklin lenses line is way more noticeable than a cast executive.

    2. If the Plano OS was a “balance” lens, she wouldn’t need prism distance ( unless it was to turn the eyes for cosmetics).

    3. She’s obviously using a bifocal monocularly since there’s only one (on the right eye), So any prism amount (induced or prescribed) in that one bifocal is mute.

    A rd seg is just like a sv lens. You can do powers and prism just like you would with a sv lens. The only issue in the above patients request is where to orient the seg. And a rd seg can fill all requests listed in the OP. (Less bifocal edge, wants seg outset, less head movement towards lower peripheral right, prism needed distance). Once again, any prism in the near area of the bifocal doesn’t matter because she’s not using them as a “bifocal”, she using them as a “monofocal”. You pretty much need 2 images to even have diplopia (other than certain medical issues like lens subluxation).

    I think this “problem” is being over analyzed. Hopefully Fester can chime in and clarify any issues we haven’t addressed.
    I'd love to add something to this thread so I can have Lensman11 tell me how ridiculously wrong I am, but optical24/7 has unsurprisingly already given all the best answers. Well done.

    I will say it's going to be a pretty weird and annoying pair of glasses to wear for anything other than driving/dash.

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    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    Quote Originally Posted by Kwill212 View Post

    I will say it's going to be a pretty weird and annoying pair of glasses to wear for anything other than driving/dash.
    I think this is why we are pausing as she sees what I'm saying will be the problem doing what she wanted and she really needs to get used to turning her head a little for the GPS.

    And why a Franklin may be in the future for driving.
    Last edited by Uncle Fester; 07-14-2022 at 09:03 AM. Reason: tweak...

  14. #14
    What's up? drk's Avatar
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    Is this an outside Rx? If not, do you have her diagnosis list re: binocular status?

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    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    Quote Originally Posted by drk View Post
    Is this an outside Rx? If not, do you have her diagnosis list re: binocular status?
    I'll try to get it next week when the doc is back and he's in a good mood.

  16. #16
    What's up? drk's Avatar
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    Oh. Well, we won't hold our breath, then. Docs are a cranky lot. Amiriteoramirite?

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    Quote Originally Posted by Uncle Fester View Post
    I think this is why we are pausing as she sees what I'm saying will be the problem doing what she wanted and she really needs to get used to turning her head a little for the GPS.

    And why a Franklin may be in the future for driving.
    I'm just kind of rambling here. But if she can't be bothered to turn her head 10 degrees to see her dash, how does she change lanes!? or park? I can't imagine getting out of my driveway, let alone my neighborhood without turning my head.

    I still can't gather why a Franklin would be necessary. Or rather how and why near prism requirement was calculated for use with only 1 segment.

    But if you need it EPIC can make prism segments and Franklins.

  18. #18
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    [QUOTE=drk;568545]Oh. Well, we won't hold our breath, then. Docs are a cranky lot.








    Amiriteoramirite?
    No. My doc is very nearsighted though.




    Somewhere in the past she was told by an MD(?) a muscle issue has the need for the distance prism but no prism in the near.

    After much discussion we landed on the one seg one sv a couple years ago for which she was thrilled.

  19. #19
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    Right, I get that in the exam room she could be tested for near prism with both eyes open. But send her back to the doc with an eye patch over her left eye and ask them to test her for prism at near. Point being the prism isn't going to matter for near if she is only using one seg. Place the seg where it is physically convenient to use, and forget about the near prism, or lack thereof.

  20. #20
    What's up? drk's Avatar
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    Kwill, I have to disagree. You are not understanding that there is central acuity and peripheral vision. In theory, if she needs prism to fuse in straight-ahead gaze (distance portion) she's likely to need prism at near, too, or she'll see double.

    Just because her central acuity is blurred out (penalized) at near due to the omission of a segment, it doesn't mean that her more global, peripheral vision doesn't need the prism! To prove this to yourself, if you want to, take a 12^ BO prism (to simulate a BV disorder) and make yourself double at nearpoint, and put a piece of tape where a seg would be on your glasses over one eye (to simulate the blur from not having a segment). You'll still have diplopia.

    In other words, the penalization of being roughly 2.50 underplussed at near will take out the near diplopia but not the peripheral outside the seg.

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    Quote Originally Posted by drk View Post
    Kwill, I have to disagree. You are not understanding that there is central acuity and peripheral vision. In theory, if she needs prism to fuse in straight-ahead gaze (distance portion) she's likely to need prism at near, too, or she'll see double.
    Well, Fester's post says "She needs prism for distance but not near" and "has worn ft28 right eye only successfully to suppress the diplopia"

    So it seems either she needs different prism for distance and near, or no prism at near as the post says. Wearing 1 seg only has already been proven successful for this patient to suppress the diplopia at near. The only change they requested, as far as I can tell, is a less noticeable line(obviously disqualifies a Franklin) and less head turning for 1 specific task(possible, but makes the glasses awkward for everything else).

    Quote Originally Posted by drk View Post
    Just because her central acuity is blurred out (penalized) at near due to the omission of a segment, it doesn't mean that her more global, peripheral vision doesn't need the prism!
    I never said it did. Grind her the 4 BO in both eyes.

    Quote Originally Posted by drk View Post
    To prove this to yourself, if you want to, take a 12^ BO prism (to simulate a BV disorder) and make yourself double at nearpoint, and put a piece of tape where a seg would be on your glasses over one eye (to simulate the blur from not having a segment). You'll still have diplopia.
    Here are my findings. Apparently there is no limit to the amount of BO prism I can tolerate and still fuse. I loaded up 18BO into the flippers then held 6 more in front, came right together and couldn't get double. Base in however worked a charm. (I assume I could just cross my eyes for this experiment?). Also I'm kinda nauseous now, but hey, anything for Drk. It obviously worked exactly how you said it would. Diplopia outside the seg but that's why we are giving her the 4BO OU, to fix that. We are just not going to concern ourselves with the near prism or trying to neutralize the 4 BO at near, because we are neutralizing it though suppression.

  22. #22
    Master OptiBoarder optical24/7's Avatar
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    Dr., if she has been using a single seg, R eye only for 2 years as stated, I can assure you, she has developed a monocular near only. Her brain has developed the habit of suppressing the left. Even though there is vision in the left, it’s blurred, and the brain likes the clear image in the right and keys in on that, disregarding the blurr image. Go to a manual lensometer ( I hope you have a manual in your arsenal). Clear up the mires through the eyepiece with both eyes open. When you did that, what did your brain key in on? Was it clear or double?

    I guess I’m not understanding “peripheral outside the seg”. The prescribed prism is everywhere outside the seg. And with a rd seg outset 10mm’s, it would create aprox 2D base in ( with the 1.75 add) negating 2D of her BO distance ( stated not needing prism near), less prism in near then better, right?

    I’ve worked with many a patient that had long term (habituated) bino/mono issues. Some were mono distance only, some mono near only. The one constant with these patients was suppression of blurred vision and focus of the clear.

  23. #23
    What's up? drk's Avatar
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    Kwill, you are a true scientist. I like you.

  24. #24
    What's up? drk's Avatar
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    Quote Originally Posted by optical24/7 View Post
    Dr., if she has been using a single seg, R eye only for 2 years as stated, I can assure you, she has developed a monocular near only. Her brain has developed the habit of suppressing the left. Even though there is vision in the left, it’s blurred, and the brain likes the clear image in the right and keys in on that, disregarding the blurr image. Go to a manual lensometer ( I hope you have a manual in your arsenal). Clear up the mires through the eyepiece with both eyes open. When you did that, what did your brain key in on? Was it clear or double?
    Monocular suppression. Yes, I can do that.

    I guess I’m not understanding “peripheral outside the seg”. The prescribed prism is everywhere outside the seg. And with a rd seg outset 10mm’s, it would create aprox 2D base in ( with the 1.75 add) negating 2D of her BO distance ( stated not needing prism near), less prism in near then better, right?
    The question was whether the penalized eye needed prism at near or not. I said "likely yes" because there would likely be diplopia outside the segment, peripherally. I was under the impression that Kwill felt she might be able to do without it, due to the central penalization. I guess he wasn't saying that. But even if he was, he may have been right, or he may have been wrong...either way is possible, based on the patient.

    I’ve worked with many a patient that had long term (habituated) bino/mono issues. Some were mono distance only, some mono near only. The one constant with these patients was suppression of blurred vision and focus of the clear
    Yes. Suppressing blur is not that hard. Suppressing diplopia is way hard.

    Interestingly, we are getting into suppression amblyopia territory. When someone has a solid esotropia, they suppress in order to avoid diplopia. But...what is it REALLY LIKE for them? Do they see "black"? Do they feel like the eye is just "covered up"? No. They are getting peripheral input without diplopia because the tolerance of "retinal disparity" (double vision from misalignment, if you will) increases off-center.

    This...is...the...dreaded...horoptor!


    So, in other words, our depth perception is less, peripherally. Our tolerance for diplopia is greater peripherally. Our vision is blurrier peripherally. Our color vision disappears peripherally. Our tolerance for flicker decreases peripherally. The only things better peripherally is our motion detection and dim light detection. (You can see stars more brightly looking off-center. Hi, Uillean.)

    Our central vision is where it's at...it's high-performance, but it can be turned down so as to not be distracting, if it's broken. Amblyopia is only central!!!! And it can be deep and embedded, or it can be shallow and malleable (depending on the situation).

    This goes on in our visual cortex at the level of the binocular cortical cells.

    But the peripheral vision is a separate issue from the central. In one way, you might say, "well, you just said it can tolerate diplopia better, so why the big deal with the prism" and you might be right. Or, I might say "she'll still get annoying diplopia peripherally so she's going to need the prism" and I might be right. Why are we debating this? Because that DANG FESTER brought up Franklin bifocals and made us think he's trying to get different prism at near. Maybe he's not even saying that. Maybe he's responsible for this big messy thread. Maybe I am responsible for going there. I wish we knew more about the case.

    I have nothing else to regurgitate.
    Last edited by drk; 07-14-2022 at 04:25 PM.

  25. #25
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by drk View Post
    Why are we debating this? Because that DANG FESTER brought up Franklin bifocals and made us think he's trying to get different prism at near. Maybe he's not even saying that. Maybe he's responsible for this big messy thread.
    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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