how much off for pd

Discussion in 'Optometry Archives' started by bear, Mar 2, 2006.

  1. bear

    bear Guest

    I just got new glasses 2 weeks ago. The optician hand measured my PD
    at 62.

    Last week I found prescription sunglasses at another shop, there the
    optician used a marker on my glasses, measured the marks, and then
    followed up with some sort of machine that measured the PD as well.
    She found my PD to be 68.

    Would, could, should, this cause me problems? Is 6 mm off on PD a

    Since then I have been getting 'tension headaches' in the
    afternoon/evenning. But to be honest, I cant quite decide if this
    started with the new glasses, or if my current stress and a little
    paranoia has set in:)

    Without naming the shop, or knowing their policies, does anyone have
    any suggestions on a possible recourse?

    bear, Mar 2, 2006
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  2. bear

    CatmanX Guest

    6mm can be significant, and it may not. It depends on the script,
    whether large or small, plus or minus, whether you have excess
    convergence or divergence facility.

    Either of the two may have been wrong, go back to your optom and get it
    checked out.

    dr grant
    CatmanX, Mar 2, 2006
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  3. If you are a U.S. citizen, welcome to the "Wild Wild West" known as
    opticianry. There is no federal standard for optician qualifications,
    and in many states it is an unregulated industry. Here in Illinois,
    for example, your hair stylist is licensed, and the person who puts
    chemicals on your lawn is licensed...but your "optician" doesn't have
    to graduate from high school. During my 25 years of practicing
    optometry here in Illinois, I have had people walk in my front door
    with two left lenses in their glasses, bifocals that were placed
    upside-down and even lenses that were switched between a husband and
    Grant is right...have your optometrist take your PD and find an
    optician you can trust.
    doctor_my_eye, Mar 2, 2006
  4. bear

    bear Guest

    Thanks to both of you for your prompt reply. I will consult my
    optometrist. But in response to catman if I post my script could you
    comment further on the 'signifigance'?

    -3.00 +0.25 002
    -3.00 +0.50 180

    The second optician (the one who was thoruogh) told me that she had
    quit her previous job at a 'national' optical store because over the
    years that she worked there, the employed fewer and fewer licensed
    opticians, and more and more 'eye candy', or as she called them
    'Brititany and Tiffinany'.

    Where she now worked, they only employed liscensed opticians.

    A lesson that I have now learned.

    bear, Mar 2, 2006
  5. bear

    LarryDoc Guest

    I thought the industry standard for PD is +/- 2mm for powers over 2D in
    any meridian and 1mm above 4.5D. As the power increases, the effect of
    mal-positioned optical centers increases.

    It also has to do with an individuals ocular alignment/positioning and
    their sensitivity to altering the convergence/divergence thresholds.
    Some folks find 1mm off to be uncomfortable and others might actually
    benefit from a 3mm error---if it's in "the right direction."

    Personally, I like to mark the horizontal and vertical centers for each
    eye separately and in the eyeglass frame to be used for the Rx. Less
    returns and unsatisfied patients that way, although it does take an
    extra minute or two to do that extra work.

    LB, O.D.
    LarryDoc, Mar 2, 2006
  6. bear

    bear Guest

    Thanks to those who commented.

    I went this morning to the store where I got my glasses. I explained
    to the optician about my eye strain and the possibility of his missing
    my PD measurement. He checked again, this time by hand and by marking
    my glasses, and he came up with a PD of 67.5. He appologized for his
    mistake and ordered new lenes.

    A final note though. He is a liscensed optician.

    Again thanks for the advice.

    Another final note :) I am quite surprised by the lack of
    stadardization in the industry. I have a quite large and round head
    and have a really tough time finding frames that do not press against
    my temple. I went to 6 different places usually without a suitable
    frame available.

    In the process I learned some about the numbers applied to the size of
    the frame. There is the bridge measurement, the eye measurement, and
    the number for the length of the arm of the frame. Excuse me if I got
    the vocabulary wrong.

    But there is no OD (outside diameter) available for the frames. What I
    mean is the actual distance from arm to arm across the frame. The
    measurement would be very helpful to me in quickly finding a frame.

    bear, Mar 3, 2006
  7. bear

    bear Guest


    Double the eye measurement plus the bridge is actually not the whole
    story. The glasses that I have found to fit have an additional piece
    between the lens and the arms. I don't believe that that is accounted
    for in the above measurements.

    I think that you could find two frames with identical measurements,
    one frame with the arms attached directly to the lens (close to) and
    the other with arms attached as much as 10 mm out from the lens.

    If I'm correct about this, then clearly the OD of the frames would be
    different, I suppose the second frame would be Bridge+(2xEye
    measurement)+(2x10 mm)= OD

    Hopefully that made sense. And perhaps I'm not correct in this. Some
    frames were marked Big Man frames. The ones I did buy are 56 19, but
    like I said, they have an additional length to them outside of the
    bear, Mar 3, 2006
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