Long time patient with latest rx not resolving horizontal diplopia unless he tips his head waaay back.
R +2.00 -.75 x 75 3.5^ out
L +2.25 -.75 x 75 2.5 out 3 up
Old rx which was worse is .25 less horizontal OU all else rx wise is the same.
Thoughts???
Assuming SV. Frame differences? Aspheric VS spherical? Base curve? Material? .25 is negligible. Vertical prism may be suspect. Anyone consider yoking this?
Spherical lenses. Glasses not made by me- think it's cr-39. Vertical image is fused. Doubling is in the distance only. Separate reading sv glasses are fine. Yoking horizontal is what the Doc is doing. Previous now retired Doc did not yoke in the past and was able to resolve the double image.Originally Posted by lensmanmd
Thanks for your input!!!
Reading is fine. OK. Perhaps a half D decrease in BO^ OU?
I know this may seem trivial, but was his horizontal prism split previously/ this time? Prism will move the image but also move the pupil. His eye muscles may be used to moving x amount. Splitting/not splitting from pair to another may have an initial nero adaptation time.
Next, once again, split/compound prism, as he moves his head up, he changes the prismatic deviation, not just vertical, but horizontal. Glancing down will be inducing less base out as the power/prism compounds. The patient may need 1, min. 1/2 D more BO. ....But I did Have a few shots of Makers Mark. Correct me gurus please!
I've seen this before. Somebody's prism can be different as they turn their head and therefore rotate their eyes. As he lifts his head, he's making his eyes converge (I think) which suggests he needs more prism than he had been prescribed.
It sounds like non-concomitant strabismus, where the deviation varies depending on the direction of gaze, about the only time we might not want to split (not yoked) the prism. Check with the prescriber and consider matching the placement of the prism of the old eyeglasses, or, as 24/7 pointed out, it might be a matter of adaptation, although I wouldn't want to walk around with diplopia for any more time than was absolutely necessary.
Hope this helps,
Robert Martellaro
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.
Thanks for the replies from all of you so far.
Robert M. The old pair's double image is about 3 times greater than the latest Rx.
Robert S may be on too something as well.
Time will tell.
I took that to mean that there was no diplopia with the old eyeglasses.
If the new Rx is three times better, give the brain about ten days to adapt. Back to the prescriber if not.
Best regards,
Robert Martellaro
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.
Sorry to say it's been over 2 weeks and the prescriber is us.
I'd feel better if the head tip didn't resolve it.
The Doc says he did rule out non-concomitant strabismus. Something about hand holding a prism in front of his eyes.
Is that how it's checked?
Sorry guys.
The Roberts sound like they're right...the typical situation would be a varying angle of deviation based on direction of gaze ("incomitance")...Yet he could be "decompensating" which generally means getting old and not being able to do any eye muscle work, at all....
If it's a weak muscle/nerve then you can force the eyes to look in a certain direction where the muscle is SUPPOSED to work, and it will be very obvious.
If indeed it's "the same in all directions of gaze" (= SA, up, down, right, up-right, down-right, up-left, down-left) (= incomitant) it means that it's hereditary/early onset or at least quite old...
Now, for testing of "comitance/incomitance" you do measure the deviation angle in all positions of gaze, which is a chore. But yeah, using a prism is a very good way to do it.
As to this case:
1. Clearly this is not new (old glasses had prism), ergo not an emergency or "fresh palsy" or whatever...
2. He has a rather large eso deviation (based on the BO prism), and a vertical deviation...we could conjure up which muscle is likely to be deviating, maybe, but who cares at this late date?
3. Why still double in primary gaze? Why not able to find the right prism amount to fuse the image in straight ahead gaze? Better re-check that prism amount. This is the important point.
4. It may be a clue (or a red herring) if he can look down and NOT see double...but still, the bigger issue is SEEING DOUBLE.
Theoretically the OD can put the lenses in a trial frame and put in the correcting prism and have the guy take a walk-about and if that works, then, yeah, it's some weird POW/base curve/material/O.C. super-sensitivity. It's somewhat "ominous" that a previous OD had to load up the prism in one eye in order to eliminate diplopia. That smacks of "super sensitivity". I have a patient like that. I always seem to remake the glasses, somehow, on her.
This stuff is complicated...I can postulate all sorts of stuff, like "he was NEVER fused with the old prism, but was able to cortically suppress the diplopia" and now with MORE prism, the images are TOO CLOSE together and he a. can't fuse (because he's never developed that ability), and b. can't suppress, either, and c. he needs the images to be FURTHER apart (less prism) in order to aid in his compensatory cortical suppression. Sounds crazy? It's possible!
More complication: the OD should be able to put in a prism to achieve fusion in straight-ahead gaze and then "stress" him with increasing amounts of prism (BI, BO) (and should be done with Red/Green glasses to alert the doc to see if he just suppresses instead of doubling) and see if his fusion is strong or weak. This is "vergence testing" (try it, sometime, on yourself and see if you can give yourself a headache).
A weak fusional state tells you that prism is going to be only delicately effective...then you have no choice but to build up the muscle power and cortical strength with a special kind of physical therapy called..the dreaded visual therapy!
Very complicated, sometimes.
Last edited by drk; 03-28-2019 at 01:38 PM.
I see this with Parkinson's, especially when it's more advanced, the prescriber struggling to find a balance for different work distances and angles of gaze, never eliminating diplopia completely. That fact the your client is improving is encouraging, although being able to temporally alleviate symptoms by posturing must be very frustrating to all parties. Hopefully you'll be able to reduce symptom to episodes of fatigue, and/or after sustained use (reading, etc.), typical for severe binocular disorders, especially with the elderly.
DrK should be around shortly.
Best regards,
Robert Martellaro
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.
I can remember the exact Px who had the issue. He was in progressives which obviously complicated it further. We did resolve it in the end by increasing prism and making sure it was split correctly.
What have you done so far?
We are waiting for the discount chain to re do it with equally yoked horizontal prism with a .25 change in one cyl (yeah-because they can;). We 're keeping the vertical only in the left.
I got a feeling we may wind up taking my retired doc out of retirement to refract him a third time.
This doc will be the 3rd OD to find the same rx imo- but the patient has trusted him for twenty years+ and he was able to resolve his diplopia- so he's naturally feeling the new doc's don't have his "touch".
The hardest part for me will be to explain why- if he tips his head way back- he can resolve the double image. So I guess if yoked doesn't work I get to tell him the bad news that he's reached a place where lenses cannot fix it.*
If this fails should we next refer him to an MD to manipulate the muscle?
The worst side of the profession by far.
*Thanks to drk even if I only half grok it.
Last edited by Uncle Fester; 03-30-2019 at 11:19 PM. Reason: tweak...
When you say yoked do you mean split?
You already corrected Uncle Festor's 'yoked prism' misspeak, in a round about way, and I did once, very specifically. And yet we're still hearing about yoked prism where none exists, at least according to the data provided.
To be clear, yoked prism is one eye in and the fellow eye out, or both eyes up, or both down. For example, prism thinning is yoked prism, vertical prism imbalance is not.
We should probably see more Rx and eyeglass wearing history, specifically, if there has ever been different values for prescribed prism on the primary and near gazes.
Best regards,
Robert Martellaro
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.
That’s what I asked in my original post. Was the prism split with previous pair/new pair? Pupils can get “used” to deviating with habitual wear. If not and or split habitually, switching from one or the other, can cause some visual confusion at least initially until neuro adaption.
To expand on the above; 1 D of prism will displace the pupil 1/3mm. With 6D of horizontal prism the pupils are displaced approx 2mm total. With split the displacement is 1mm each eye, if not split 2mm on one eye only. If habitual wear is split and the new lens are not, or vis-à-vis, the displacement of each eye is different than the habitual, opening up a new can of worms and adaptation time.
I heard you (post #7), but Fester later said said it's been 2+ weeks, making it moot. He also said it wasn't non-concomitant strabismus, about the only reason to not split the prism.
I don't understand why anyone would fill a prism Rx at a discount chain, or any complex Rx/lens design (including multifocals) for that matter.
Best regards,
Robert Martellaro
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.
Mea culpa. Seriously. No yoke.
Split is it.
As far as I can tell from training and experience, there's no difference between 1 BU OD+1 BD OS<------->2 BD OS.
I mean, yeah, you can do things for cosmetics.
But there's no optical difference.
NOW! Suppose you have a higher amount of prism loaded in ONE eye, only....the optics will be worse (chromatic aberration, etc.). So, sometimes, you may find an amblyope who is quite super-picky in their "good eye" and wants super-clear optics, and the other eye can't tell because it's not sensitive. In that case, hey, load up the crappy prism view in the crappy eye, if you want (presuming it's an adult)(presuming the cosmetics won't suffer).
In fact, in the one-or-two weirdo cases that I've seen where IT MATTERS that you put all the prism in one eye (instead of splitting) I wonder if it's not to "penalize" the lesser eye, in order to promote the dominance of the good eye. Hey, these people have messed up vision. It gets very odd. As we all know, vision = brain = perception = trouble!
Last edited by drk; 04-02-2019 at 11:35 AM.
Thanks, I'm going to use that, maybe on my tombstone.
Robert
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.
Agreed.
What if the Dr. wrote 2BU right eye and no prism left eye, with the specif note not to split the prism. What if I order with 1D of equithin? GASP, we would then have 1 BU and 1BD. Furthermore, without the invoice how you anyone know if I split the prism or if I ordered equithin?
Hello Kwill212.
The effect on the eyes would essentially be the same, 2∆ of vertical imbalance BU OD, although the introduction of prism thinning would run counter to the spirit, if not the intent of the Rx, especially when the Rx specifically says 'do not split prism'.
For example, for the above Rx, 2∆ BU OD without special instructions, I would interpret as split as needed for optics and cosmetics.
In other words, the onus is on the prescriber to communicate that the prism must be split in an unorthodox way.
Yes, if I had the Rx and client in front of me, I would know if the prism was split, and if there was yoked prism for thinning. However, no one could know if we don't understand the prescribers intent.Furthermore, without the invoice how you anyone know if I split the prism or if I ordered equithin?
Best regards,
Robert Martellaro
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.
I was away golfing at Myrtle Beach (no aces this year for me) and did not dispense the redo. Just called him now and the splitting prisms did the trick in resloving the diplopia.
Thanks for all the well received informative discussion and advice.
OptiBoarders RULE!!!
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