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Thread: Px distortion problem.

  1. #1
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    Px distortion problem.

    Hi, just looking for advice please.

    I have a patient complaining that as soon as he looks off centre in his polarised single vision sunglasses he experiences distortion so bad he cannot drive in them and has to take them off.

    He has had single vision rimless specs in the same RX with the same OC’s which are fine.
    Rx is +1.75DS in both eyes.

    Any ideas what could be the cause of this?

    Thanks

  2. #2
    Rising Star
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    It is possible that one or both of the lenses are off polarization. It is common error at the lab being they are spheres the mark up person could easily forget to watch the polarization axis. You can check it with a Plano Polaroid lens hold 90 degrees from 180 both lenses should be blackened.

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    Thank you. Just tried this and both lenses went dark so looks like the polarisation axis is ok.

    Really puzzled unless it is the base curve?

  4. #4
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    Quote Originally Posted by NESDO View Post
    Thank you. Just tried this and both lenses went dark so looks like the polarisation axis is ok.

    Really puzzled unless it is the base curve?
    Are spheric or aspheric lenses?

    oc height are ok? there is more panto tilt?

  5. #5
    Rising Star
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    Check if the lens is warped. Use a lens clock and check at 90 and 180. The true base curve will be at 90, compare that with the other glasses the patient is wearing.

  6. #6
    Ghost in the OptiMachine Quince's Avatar
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    Wrap is definitely something to look further into. What curve are the lenses on and if it is a wrap, has it been compensated? For a mild plus RX, it usually isn't a problem but if they have never worn a wrap before, it'd be my place to start.
    Have I told you today how much I hate poly?

  7. #7
    OptiBoard Apprentice OptiBoard Silver Supporter Optical Roy's Avatar
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    Quote Originally Posted by Quince View Post
    Wrap is definitely something to look further into. What curve are the lenses on and if it is a wrap, has it been compensated? For a mild plus RX, it usually isn't a problem but if they have never worn a wrap before, it'd be my place to start.
    I agree, if the wrap is 8 or better and they have not worn, the distortion may be the issue. Not very common in a plus sphere, but it is possible.
    Roy W. Jackson, Sr. ABOC

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