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Thread: Within ansi standards

  1. #1
    OptiWizard
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    Within ansi standards

    Let’s get some opinions on this Rx if it is within standard

    R +2.00 -4.00 x 45
    L +2.00 -4.00 x 135

    PD R 31. L 35

    received Rx was correct but the PD was off

    PD R 34. L 32

  2. #2
    Master OptiBoarder
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    Yes

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    Master OptiBoarder optical24/7's Avatar
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    If these were spherical lenses, they would pass (there's no power at 180). But if they were aspheric/atoric they would fail (asphric centers would be off 3mm each).

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    Master OptiBoarder AngeHamm's Avatar
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    Absolutely not.
    I'm Andrew Hamm and I approve this message.

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    Master OptiBoarder optical24/7's Avatar
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    Quote Originally Posted by AngeHamm View Post
    Absolutely not.
    Could you elaborate?

  6. #6
    OptiWizard
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    Patient was wearing same Rx, frame size, base curve and lens material with the correct PD with no issues. They are complaining of eyestrain and double vision with the new pair.

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    Actually this fails inspection if the you check the Rx at the PD it was ordered. You will over see 1 diop vert imbalance. This shows that Prentice rule only works on spherical lenses or lenses at axis 90 or 180. It is Prentices rule meaning rule of thumb not Prentices law meaning it would apply all the time. You actually have to calculate the power of the prism in the axis 135 and 45 and combine the prism for the result. You don’t have to do the math just use the calculator in Opticampus. Use. An optical calculator, induced prism calculator. Place a similar lens in the lensometer and move it to see the result.

  8. #8
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by Lensman11 View Post
    Actually this fails inspection if the you check the Rx at the PD it was ordered. You will over see 1 diop vert imbalance.
    Lenses with cylinder power also produce a separate prismatic effect through the meridian of the lens containing the cylinder power, 90° away from the cylinder axis. If the cylinder axis is at an oblique angle, moving the lens to the right or left will actually induce a vertical prismatic effect in addition to the horizontal prismatic effect. Furthermore, if one meridian of the lens is plano in power, the lens will not have a true optical center, because the plano‐powered meridian of the lens will have zero prismatic effect. These optical characteristics can sometimes make verifying the prism in lenses with cylinder power challenging. -D. Meister

    http://experiencevelocity.com/static...7b3ecc2612.pdf
    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.



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    Master OptiBoarder optical24/7's Avatar
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    This is what I like about OptiBoard, always something to learn. Thanks!

  10. #10
    Master OptiBoarder OptiBoard Silver Supporter
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    Quote Originally Posted by optical24/7 View Post
    This is what I like about OptiBoard, always something to learn. Thanks!
    At least they got the Bino PD correct

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