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how important is it to do a binocular balance?

Discussion in 'Optometry' started by Carly Ess, Dec 31, 2008.

  1. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    Is it really that important to do a binocular balance? As long as someone can see 20/20 in each eye independently, isn't that good enough? And what about those people with one eye that is very different than the other in terms of their prescription?
     
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  3. KHE

    KHE Senior Member
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    Well....

    What exactly is it that one does when performing a binocular balance? (I don't mean how do you do it, I mean what are you trying to do by performing the procedure in the first place?)
     
  4. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    you just balance how good each eye can see (so that if one eye sees better than the other, you make the them see the same bluriness). But shouldn't you just make both eyes see the best possible independently?
     
  5. KHE

    KHE Senior Member
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    That is not technically correct.

    The goal of a binocular balance is to equalize the.......?????? what??
     
  6. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    in my notes it says accomodation, but shouldn't we make each eye see the sharpest possible to make accomodation easier?
     
  7. KHE

    KHE Senior Member
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    It is not just accommodation...it is the STIMULUS to accommodation. There is a difference between those two things.

    Making each eye see independently sharper or the "sharpest" does not always give you the same stimulus to accommodation between the two eyes.
     
  8. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    So in other words, making the stimulus of accommodation of each eye the same will make sure that a prescription doesn't cause head aches? Or are there other problems that can arise?
     
  9. 4Eyes

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    Also, if you don't balance, there are always those patients who will eat minus. So, for example, one eye may end up having to accommodate for distance while the other won't. There are doctors out there who don't balance, and I imagine they lose a lot of money because they do more remakes or the patients go elsewhere because they don't like their glasses. Even if people see clearly out of each eye, something just won't feel right (or they might have headaches, etc).

    Even after balance, they shouldn't really lose a significant amount of acuity. If there's a big difference in BVA in each eye, you don't want to prism dissociate....
     
  10. KHE

    KHE Senior Member
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    Performing a binocular balance will not ensure that a patient will not have headaches or eyestrain or any other problem with their Rx. However, it is one of the bigger sources of problems, at least in my experience.

    Now, truth be told. I do not do it on all patients. With experience, you come to learn which patients "need" one and which ones do not.
     
  11. 362.04

    362.04 SDN Mentor
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    Patients walk around, watch television and read usually with two eyes open at the same time. It may seem intuitive that each eye should be maximally corrected and tested individually, but what counts just as much is the comfort of that two eyed vision.

    For the most part, the binocularly balanced refraction will be close to the individual refraction of the eye. In circumstances where the binocular balanced refraction is most relevant are amblyopic eye or where there are asymmetric visual acuities. In these cases, the examiner/refractionist may be tempted to maximally correct each eye.

    But because accommodative effort of each eye are tied together, over correcting the worse eye will cause over accommodation in the better seeing eye. Ergo, Discomfort on effort.
     
  12. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    Thanks for everyones replies. It makes so much sense now!

    Also, KHE, you mentioned that you have learned that some patients will need a balance more than others. Can you provide some examples of what will ring a bell for those patients?
     
  13. KHE

    KHE Senior Member
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    A few of them....

    1) Patients who's refractive change doesn't match their entering acuities. eg. the 20/30 patient who refracts with a diopter of change.

    2) Patients who have near 20/20 vision yet seem to be going back and forth between stronger and weaker Rxs.

    3) Any anisometropia greater than 1.00 diopter in the vertical or horizontal meridians.

    4) How "good" their responses are to the refraction or other testing.
     
  14. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    I have heard that some doctors balance by doing a red-green test instead of the binocular balance with prisms.

    Is this just as good? Also, I heard it was done monocularly, making sure that the patient is not overminused in the green. Shouldn't we do it binocularly?
     
  15. KHE

    KHE Senior Member
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    I always use the red/green test and do it binocularly. That is, IMHO the best way of doing it. It is not done monocularly. It is done with +1.00 fog over the non tested eye to suspend foveal fixation.

    Also, the goal is almost always to make them one click into the green.

    As the saying goes, keep them in the green and they'll keep YOU in the green.
     
  16. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    So in other words, the doctors who do the red green monocularly are doing it wrong?

    With it being done binocularly, should I just put in the prisms to dissociate, and then fog one eye with +1, get them one click into green, and then fog the other eye and do the initial steps?

    Thanks for all your input, I really appreciate it. :)
     
  17. 4Eyes

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    I don't red-green balance everyone, but I red-green balance everyone who isn't good for just prism dissociation. I don't think everyone responds well to it, though not everyone responds well to prism dissociation either. It IS possible to do R/G balance while prism dissociated...I'm not sure you have to fog in that case (?) ...I never do it that way.

    Also, I think I've read ABOUT studies (I haven't read the actual studies) that would indicate that prism dissociation / alternate occlusion works more often than just R/G. However, I've heard lots of ODs say that's ridiculous. I just graduated in May, so I'm still in the process of figuring out my favorite way to do things.
     
  18. KHE

    KHE Senior Member
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    The people doing it monocularly aren't doing it "wrong" per se, but they are doing it in a less than optimal way.

    The problem with doing it monocularly, which is the same problem with the prism dissociation technique is that both of those methods prevent fusion of the monocular images.

    What that does is it eliminates fusional vergence. Because of that, the vergence response and therefore the accommodative response may be different from what you would get under normal binocular viewing.

    I also respectfully disagree with the other poster who suggested prism dissociation works better. In a patient with unequal acuities, the red/green will virtually always work better because with prism dissociation, the poorer seeing eye will always be worse in comparision to the good eye. The red/green test does NOT require comparison between the two eyes, which is one of the major advantages.

    In fact, when I refract, I do it binocularly. I don't occlude one eye.
     
  19. 4Eyes

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    Just wanted to clarify...I'm not saying prism dissociation works better. Just saying I've read things like that. Though I'm not sure "works more often" is always the same thing is "works better." It seems like a lot of people (well, not a lot, but a significant enough number) always say "red" no matter what. Anyway, since I read that, I've heard more ODs saying things more in line with what you're saying, and it makes a lot of sense. So that's why this newbie OD is experimenting with techniques. :)
     
  20. WoodyJI

    WoodyJI Junior Member
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    It's funny you mention that b/c I've actually had a lot of px say that the green side looks better right off the bat. And I have to go through the test almost twice to get them to understand exactly what I mean. For instance, they'll be fogged up, and claim the green side is clearer. I'll remove one click of that plus fog, and now they understand that the red side has been clearer the whole time...or I'll dim the lights more and try the test again.

    I've found that it's important to have the lights really dim for the test to work well. Bigger pupils enhance chromatic aberration, facilitating the patient's sensitivity to the test.
     
  21. WoodyJI

    WoodyJI Junior Member
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    Do you use polarized charts or do you fog up the eye you're not actively refracting? Do you consider this to be common practice? I can't say I've run into many attendings who do binocular refraction, although I know it exists.

    On another topic, does anybody here ever use the clockdial test or other alternatives to the Jackson Cross Cyl technique?
     
  22. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    yeah, i've tried the clock dial test. the darkest line is where the astigmatism is.
     
  23. iowaeyes

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    Are you sure they aren't doing the red/green sphere check test? This test is done monocularly to confirm the power of the sphere. We learned to use it if ret results are less than optimal (in conjunction with a clock dial if necessary). Then you would continue on in the regular refraction.
     
  24. iowaeyes

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    Obviously, as a student I am by no means an expert, but I really like the Eliciting Cyl procedure if I get 0.25 D or less on the ret for cyl power.
     
  25. WoodyJI

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    I'm sorry, but I'm not quite sure that I've heard of this technique. Maybe I know it by a different name...how exactly do you perform the eliciting cyl procedure?

    Do you mean checking every 45º with the flip cross, or something more than that?
     
    #24 WoodyJI, Jan 6, 2009
    Last edited: Jan 6, 2009
  26. WoodyJI

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    I think what KHE is saying is that you do the R/G test without prisms; both eyes un-occluded (normal binocular viewing) and fogged to start.

    If you do dissociated R/G, then you're essentially doing a monocular test—you may as well occlude one eye and forget the prisms, as others have mentioned here. It's not a binocular test b/c the eyes aren't working together (fusional/accommodative vergence absent). One might do a dissociated R/G if they're interested in flipping less knobs on the phoropter...otherwise, I believe it's basically the same test.
     
    #25 WoodyJI, Jan 6, 2009
    Last edited: Jan 6, 2009
  27. 362.04

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    There are generally two or three truly binocular balanced refractions:

    1. Turville Infinity Balance (TIB)
    2. Humphriss
    3. Stereoscopic refraction
     
  28. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    So to make sure I really understand the setup for the R/G binocular method:

    After refracting each eye individually, I then open up both eyes.

    Then I add +1.00 to OS, and modify the OD while having the R/G up until balanced or in green.

    (remove +1.00 OS) Then I add +1.00 to OD, and balance the OS.

    Finally, remove +1.00 OD.

    Is that right?
     
  29. KHE

    KHE Senior Member
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    That's pretty much it.
     
  30. Carly Ess

    Carly Ess Bananas=Guilty Pleasure!
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    Thanks for your help :p
     
  31. iowaeyes

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    I think it is the same as you are describing. You add a quarter to the cyl bank, have the JCC in Power Check, and check every 45 degrees. If the patient chooses "red" or more cyl or says same, then you switch to regular JCC and do Axis Check and Power Check as normal. If they choose "white" or less cyl at each 45 degree meridian, then you remove the 0.25 D cyl from the bank and move on.
     

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