Prism correction

Discussion in 'Optometry Archives' started by Charles, Nov 23, 2005.

  1. Charles

    Charles Guest

    I've posted a few times on here about how I'm currently doing vision
    therapy. I'm having some sort of eye teaming/convergence problem, and
    the doc identified that my eyes relax slightly outward. I don't know
    all the correct terminology to use. I have a fairly mild Rx, almost
    all astigmatism in the 180ish axis (I hope I'm saying that right)
    around -1.00.

    When she first came up with my diagnosis, I asked when prism correction
    is appropriate, and she said that for me it wouldn't work. I didn't
    really understand the explanation, something like that my eyes would
    just adapt to the prism and I'd have the same problem over again.

    In going through this VT stuff though, one of the things I'm doing is
    looking at these tranaglyph things with red/green glasses. They
    basically seem to be making it so I need to go fairly well cross eyes
    to converge the red and green images, as though I were looking at
    something very close to my face. I suppose the red/green thing is
    important because it makes it really obvious if one eye gives up.

    Now to the point. I've noticed that after looking at some of these
    really close things for a few minutes my vision is much more blurry.
    It takes several minutes to get back to normal.

    Here's my theory: the fact that my eyes tend outward is physiological.
    I developed my astigmatism when I started doing a lot of close computer
    work (this is true), because I maintained this close convergence for
    long periods of time and it physically affected the shape of my
    eyeballs (pulling my eyes together far from their desired/relaxed
    state). Looking even closer with these 3D cards temporarily makes the
    astigmatism even worse. Is this reasonable?

    If this is the case, would it make sense to get some glasses with prism
    correction for close work to take some of the strain off? It seems
    that after some time of using them, I might be able to remove the
    astigmatism correction if my eyes can go back to their "pre close work"
    state. I'd much rather have glasses to wear while reading, and then
    not wear any for normal daily activities.

    Am I making this all up? TIA
    Charles, Nov 23, 2005
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  2. Charles

    Charles Guest

    Are you joking? I don't think it's at all unreasonable to consider
    that one's eyes could be affected by straining to cross them far away
    from their relaxed state. A better analogy might be, would your arms
    get longer if you started hanging lead weights from your hands all the

    I'm not saying I know my theory to be true, but it deserves more
    consideration, or a more reasoned explanation of why it is wrong.
    Plus, I came across a journal article indicating that symphony
    musicians tend to develop astigmatism in the axis corresponding to the
    way they cock their heads to read the music. I'll dig it up if you

    And if I'm wrong, I'd like to find out why my vision becomes blurry
    after my eyes are "crossed" for a few minutes during vision therapy.

    Charles, Nov 23, 2005
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  3. Temporary muscle spasming, yes, structural change, no.
    Great analogy. They might feel like they're getting longer, but you'll
    never be an orangutan.
    Bogus idea, popular eons ago. My sis is a pro violinist and her
    astigmatism hasn't changed significantly since she was a little girl.
    Muscle tonus. Totally understandable and expected.

    w.stacy, o.d.
    William Stacy, Nov 23, 2005
  4. Charles

    Charles Guest

    Here's a link to the article. Are you saying it's garbage? I
    contacted the author a while back and he still stands by it and is at
    least reaosnably well, if not highly, respected in the field as far as
    I can tell:

    Besides, I simply find it very hard to believe that my eyes randomly
    got worse in the course of a year or two after starting ~8 hour per day
    computer work (after being 20/20 for 24 years). Anything's possible,
    it just seems unlikely and I'm not hearing any other explanations.

    Does anyone have data that correlates the number and severity of
    prescriptions with the amount of reading and close work a person does?
    I work in an environment where everyone reads and uses computers
    constantly, and 2/3 of us wear glasses. Maybe other people just don't
    care about blurry vision, I don't know.
    Who knows. I bet if you stretched yourself on a rack 8 hours a day,
    you'd be a few inches taller after a year. I also think you'd settle
    back after a while if you stopped.
    I'm sorry, what does this mean?

    Charles, Nov 24, 2005
  5. Charles

    Charles Guest

    Mike Tyner wrote:

    Thanks for the reply. I may not be understanding what you are saying,
    but the thing I don't understand is that when I'm doing this VT stuff,
    my eyes, individually, are focussing at normal reading distance. The
    thing that's different is that they are much more than normally
    "crossed". When The exercise is done, things are blurry at that same
    distance. So it appears related to the strain of the eyes crossing,
    not the fact that the eyes have been focussed at a certain distance for
    a long time. I'm still fairly young; my eyes go between close and
    distance quickly. And the VT exercise is only for a few minutes
    anyway, nothing like reading a book for hours and then trying to look
    far away (which I don't really have trouble with anyway).

    Charles, Nov 24, 2005
  6. Charles

    Dan Abel Guest

    I'm retired now. I recommend it highly, although the pay isn't great.


    I try to walk three hours a day. I often do more. This is very good
    for my health. Of course, I have to realize that all this walking is
    going to shorten my legs. Isn't it?

    Wait a minute! Doesn't exercise make things *bigger*? Shouldn't my
    legs actually get longer because of my walking?

    I am anxiously waiting all of your expert opinions about whether my legs
    are going to get shorter or longer because of all my walking. After
    all, should I stock up on longer or shorter pants?

    Dan Abel, Nov 24, 2005
  7. He may be a prolific writer, but I think he is pretty far out of the
    mainstream of thinking in the field, or at least he was when the article
    was written 18 years ago.
    I don't disagree that extended computer use has precipitated an increase
    in myopia. I've obvserved it over the years. I think you were referring
    to short term stresses doing the same thing, which is what I challenged.
    There are loads of data on this. Everyone knows that myopia is largely
    an effect of excessive close environment of the post-industrial age. The
    devil is in our inability to prevent it.
    No argument there.

    Human skeletal muscle, when continuously stimulated, tends to retain a
    semi contracted state for a period after such stimulation.

    w.stacy, o.d.
    William Stacy, Nov 24, 2005
  8. Charles

    Charles Guest

    Wow, I'm pretty disappointed in this group. Is it really inconceivable
    to the point of absurdity that if you use your eyes in ways that strain
    and pull them that they might change shape slightly? As I said, it may
    not actually be true, but you need to either do better than this or
    just keep quiet about it.

    Charles, Nov 24, 2005
  9. Charles

    CatmanX Guest

    What do you expect from a usenet group? Everyone to listen to your
    arguement and agree??

    There is plenty of research showing astigmatism developing according to
    the direction of eye movement, but it relates more to the lid pressure
    than anything else, not eye muscles.

    Secondly, the problem you have is convergence insufficiency, not
    exophoria. In CI, you ability to converge is impaired. The vision
    therapy you are doing is to train your system to be able to converge
    with ease. Prism correction will not achieve anything as the underlying
    issue is an inhibitory centre in your brain and this inhibitory pathway
    must be overridden in order to get you working comfortably for close

    CatmanX, Nov 24, 2005
  10. Charles

    Dan Abel Guest

    I was just trying to make a point, that just because something *seems*
    like it ought to work a certain way, that doesn't mean that it actually
    works that way.
    Dan Abel, Nov 24, 2005
  11. Charles

    Charles Guest

    Absolutely not. I just hoped that I would not be mocked when I feel
    that my "theory" is at least conceivable. An explanation of why I'm
    wrong (for example, is the anatomy of the eye such that straining to
    cross the eyes could temporarily flex the eyes and change their shape,
    or not?), or a statement that research has proved otherwise, would
    suffice. Better yet, a plausible explanation (besides pure randomness)
    of the symptoms I'm seeing, like my vision getting worse when I started
    doing more close work, would be great.
    Okay. Interesting how previous replies would indicate that I'm a moron
    for even considering that how the eyes are used could affect
    astigmatism at all. Something about peoples' ears not changing shape
    from listening too hard.
    Help me understand the difference. I think the diagnosis was made
    based on my explanation of symptoms and the movement of each of my eyes
    when covered. Possibly also based on my verbal indication of when it
    became difficult for me to maintain convergence/divergence with prism
    lenses (I'm assuming, she didn't tell me what was actually happening
    all the time). How are the symptoms different between brain related
    convergence problems and physiological issues (exophoria?).
    If the natural resting state of my eyes is slightly outward, is prism
    appropriate? If not, when is it?

    Charles, Nov 25, 2005
  12. Charles

    Charles Guest

    William Stacy wrote:

    You're the expert. It just seemed more than reasonable to me that
    perhaps straining to cross the eyes over the long term might actually
    pull on the eyeball in one dimension causing elongation and
    astigmatism. The anatomy of the eye would say whether this is even
    possible, and which dimension the astig would be in if it were
    possible. I'm a total lay person, so if you say the data and/or
    anatomy doesn't support this, I believe you.

    Is there data on the astigmatism impacts of extreme close work? I say
    "extreme" because my theory was that if I'm starting with eyes that
    want to tend more outward than normal, "normal" close work might affect
    my visual system in the same way as repairing watches (or whatever)
    would for the average person.
    Charles, Nov 25, 2005
  13. Charles

    Charles Guest

    Help me to understand. The muscles you are considering here are the
    ones that "point" the eyes, right? These are the ones under stress
    while I'm converging them for the tranaglyph. If those muscles were
    having trouble, how would that make my vision blurry? Isn't that
    determined by different muscles, the ones that do the actual focusing?

    Charles, Nov 25, 2005
  14. Charles wrote:
    It just seemed more than reasonable to me that
    If you look at the anatomy of the extraocular muscles, you'll find they
    exert primarily a tangential pull on the eye, which causes it to turn,
    not to elongate.

    The anatomy of the eye would say whether this is even
    The anatomy speaks for itself. That is not to say that what you are
    suggesting is "impossible", and I do believe that small forces over long
    periods of time can and do influence the shape of the eye.
    In over 30 years of practice and monitoring thousands of eyes developing
    over time, I've seen little change in most peoples' astigmatism. I've
    seen large changes in myopia, but relatively little in astigmatism
    (except for eyes that are injured or diseased, or those that have been
    subjected to long term contact lens wear).

    w.stacy, o.d.
    William Stacy, Nov 25, 2005
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