can you accomodate one eye only?

Discussion in 'Eye-Care' started by same, Oct 14, 2003.

  1. same

    same Guest

    hi i have a cousin he is farsighted in one eye only. his other eye is
    plano. his doc says he can accomodate to see clearly far away. he was
    given contact lens in one eye only. now if his farsighted eye can
    accomodate to see clearly then why would he need contact in that eye?
    can't his good eye stay normal and his farsighted eye accomodate at
    the same time? TIA

    same, Oct 14, 2003
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  2. Hey Same,

    It is simple, when your cousin accomodate,both eyes are getting the plus
    addition in the same amount ( in normal circumstances)
    The error in the far sighted eye can be corrected that way but in the same
    time you are getting a too much plus correction in the emmetropic eye (the
    plano one).
    In other words, when not accomodating the emmetropic eye sees sharp in the
    distance and the hyperopic (far sighted) blurred.
    When accomodating in the right amount, the hypermetropic sees sharp and the
    emmetropic eye (with the plus addition) sees blurred at distance.
    Further more, it is a good thing to see sharp at distance without having to
    accomodate and to have a simultaniously good and sharp vision with both eyes
    at the same time.
    The doc is right!
    All this is said for normal conditions BTW.

    Jan (normally Dutch spoken)
    haalditwegoudes, Oct 14, 2003
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  3. same

    RM Guest

    it is extremely difficult for the eyes to accommodate differentially. That
    is, the human body isn't "wired" very well for 1 eye to accommodate a lot
    while the other doesn't. It's a good idea to wear a contact in the
    farsighted eye as your cousins doctor suggested.
    RM, Oct 15, 2003
  4. same

    Chris_V Guest

    I know people that are doing research on wearable computers. With this, they
    use a tiny screen just in front of one eye. They claiim they can accomodate
    with their left eye for screen viewing and their other eye in the distance
    at the same time. They claim that the images blend together. This way they
    get 1 image of the one eye with the image of the screen blended in. I don't
    know if it's true but these guys are people that are very known in the
    academic world.

    kind regards

    Chris_V, Oct 15, 2003
  5. same

    Otis Brown Guest

    Dear Dam,

    Can your cousin read the eye-chart at 20/20?

    If so, it is difficult to understand why a plus (or minus)
    would be used.

    Also HOW "farsighted" is he. +1/2? +1.0? +5?

    It makes a difference.


    Otis Brown, Oct 16, 2003
  6. same

    Chris_V Guest

    That tiny screen is too close for most people to accommodate for it, so it
    These guys wear glasses. I think it are plus lenses :)
    Chris_V, Oct 16, 2003
  7. same

    same Guest

    His precription for left eye is +1.75, but his doctor said his true
    precription is about +3.50. he wants to correct halfway due to the
    spasm and then correct more at the next visit after my cousin got used
    to the current prescription. he sees about 20/40 in the left eye, but
    if he strains really hard he can see few letters in the 20/20 line.

    same, Oct 16, 2003
  8. same

    Dan Abel Guest

    It's easy for me to understand. However, being that I was very
    near-sighted most of my life, my understanding my not be correct.

    It isn't perfectly clear from what was posted originally (see above), but
    if the cousin can accommodate to see clearly at distance, that implies
    that he *can't* accommodate to see clearly up close. The contact will
    allow him to focus both far and near with both eyes, thus helping his
    depth perception.
    Dan Abel, Oct 16, 2003
  9. same

    Otis Brown Guest

    Dear Jan,

    In fact I do suspect the real reason.

    There a pilots with focal status of +0.5 diopters each
    eye. Because of age (50 years), they can not
    read "up close.

    What is done in that case is to put a mild plus 1 or 2 diopter
    contact on one eye. Because the mind can
    "merge" the two images, this step allows
    clear distant and near vision.

    I was curious if THAT were the reason for
    the use of a plus (or minus) contact lens.


    Otis Brown, Oct 17, 2003
  10. same

    Otis Brown Guest

    I only suggest what some ODs and MDs do for pilots
    who have focal states of zero (emmetropic by your description),
    and have a range of accommodation from zero to -1.0 diopters.

    For that reason, images closer than 1 meter will be blurred,
    depending on depth-of-field, and therefore illumination level.

    Provide the pilot understands the goal, it is possible
    to put a +1.0 diopter lens on one eye, and allow him
    to see at -2.0 diopters (or 20 inches).

    This works, and depends on the pilots choice.

    Since the word "emmetropia" has rubber-bands on it, I simply
    do not use the word. Just say 20/20 and a focal state
    from zero to some positive value.

    I hope the above description is clear about how
    a "plano" pilot with presbyopia, and use the
    "fusion" capability of the eye to restore
    some of his near vision.

    Focal status is a simpler and clearer term.

    You check this by reading the eye-chart at 20/20 (3/8) inch
    letters. This will confirm 20/20 for you.

    The next step is to apply +1/4 diopter lenses in increments
    until you find a lens that "just blurrs" the 20/20 line.

    Depends on what your mean by "too much". For natural I would
    refere to the required visual standards at the U. S. Naval
    academy. They required.

    1. 20/20 vision -- both eyes

    2. Focal status of no greater than +1.5 dipoters.

    The standard term you use would describe these
    eyes as having "refractive errors". I believe
    this is not correct in misleads anyone.

    Would you describe them as "normal" or emmetropic
    or hyperopic. Where do YOU draw the line?

    Sinc we do not have any details it is not possible to
    make a real judgment. If he had said the focas
    status is +0.5 diopters then we would have known
    with precision.

    I have heard that term also. But since the person sees with
    both eyes, and the brain selects the sharper image, then
    the question is -- does it really matter?

    We still do not know what the "real reason" was, since
    we do not know the man's focal status. If he
    were "hyperopic" at +1/4 diopters, (or do you
    call that "emmetropic") then the amount of
    "refractive error" would make a difference.


    Otis Brown, Oct 18, 2003
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