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Thread: What is this?

  1. #1
    Rising Star
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    Question

    What is the word for the phenomenon that occurs when one lens is tinted darker than the other resulting in problems w/ depth perception? An example was given to me that a pt. with mis-matched lenses would see a pendulum, not swinging, but going in an elliptical motion.
    I couldn't believe I had never heard of it before and now I can't remember the term for it

  2. #2
    since 1964 Homer's Avatar
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    Probably something like anisotintopanamonia.

    I could have the spelling wrong ;-)

  3. #3
    OptiBoard Apprentice
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    Post

    The Pulfrich phenomenon. The speed of neural pathways from eye to brain are correlated to the brightness of the signal, so the eye with the slightly darker edges has a slower transmission rate, throwing off the binocular vision system and making the object appear to be travelling in an elliptical path rather than back and forth. The greater the difference in light transmission, the larger the '3-d' effect (until, of course, no light arrives from one eye and the object appears to travel back and forth again!).

    RP

  4. #4
    Rising Star
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    Big Smile

    YAAAAY RP!!! Thank you very much.

    Thanks Homer for that neato word..next time a pt. brings in a pair of glasses purchased elsewhere to be tinted, and they're poly, I'll tell them it will cause anisotinto...that word you said!

  5. #5
    Master OptiBoarder Alan W's Avatar
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    Post

    The next time a patient comes into my office with that complaint, I'm sending them to you!
    Either that or to the shrink next door.
    In either case . . . the condition I will get from this is gas!

    I just spent 4 months addicted to Codine because three doctors and a nuclear medicine doctor all insisted I had osteomyalitis and might lose my foot. My PCP wanted to put me on disability for 6 months. Friday I saw an orthopedic doctor who said I had none of that. He magnified the x ray and said . . .
    "Take a look. You smashed your big toe joint to smitherenes!" He put me in a "cam walker today. The pain went away in 10 minutes."
    Please . . I don't want to know about light rays arriving late causing an eliptical whatever and malfunctioning depth perception!!!!
    Luv ya all!!!

    PS Do I sound like a real grump?

  6. #6
    OptiBoard Apprentice
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    Post

    Strangely enough, the latest issue of Optometry has a Pulfrich phenomenon article in it. In this case, though, optic nerve damage from glaucoma caused differences in speed of transmission of nerve impulses, so lenses of different tint were used to try to 'equalize' the transmission speed and reduce symptoms associated with the problem!
    Many (not all) of the patient's symptoms were alleviated through differential tinting.

  7. #7
    Master OptiBoarder JennyP's Avatar
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    Redhot Jumper

    RP: Makes me think of the 3-D glasses for the Imax movies... :D
    jennyp

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