Refraction...

Discussion in 'Optometry Archives' started by John Yasar, Jun 7, 2005.

  1. John Yasar

    John Yasar Guest

    Hi folks,

    When I had my refraction check, I had to look into a machine where it
    measured the refraction I think, what is this machine called, how does
    it work?

    And, when you don't have a cyclo refraction, just you look through the
    machine, what is it called, manifest refraction?

    --
    PV2 Yasar, M
    U.S. ARMY
    AH-64D "Armt Dawg"
    A Co/602d ASB/2ID/EUSA - South Korea
    Tuesday, 07 Jun 2005 / 17:19:34 Korea Standard Time (+0900)
     
    John Yasar, Jun 7, 2005
    #1
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  2. John Yasar

    John Yasar Guest

    Ok then this is not it, I didn't have to do anything, I was just told to
    look in there and the image in the machine kept going blurry and clear.
    This must be it. How does it measure the refraction, is it an estimate
    due to ciliary muscles not being paralyzed?
    Roger, does it depend on the person and the type of myopia on how much
    does it differ from autorefrac and cyclo?

    Thanks....


    --
    PV2 Yasar, M
    U.S. ARMY
    AH-64D "Armt Dawg"
    A Co/602d ASB/2ID/EUSA - South Korea
    Tuesday, 07 Jun 2005 / 20:45:17 Korea Standard Time (+0900)
     
    John Yasar, Jun 7, 2005
    #2
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  3. John Yasar

    Dr. Leukoma Guest

    I use a streak retinoscope at the beginning of every refraction. By
    blurring the patient with plus and moving the light across the retina
    in various meridians, I can estimate the refractive error to within
    about 0.50 diopters. It takes less than five minutes for both eyes.
    The autorefractor uses the same principal, except that the light is
    non-visible infrared.

    I once had a patient who was a myope of -2.50 diopters, and who wore
    contact lenses. Two years later she came back with a prescription of
    -7.50 in eyeglasses. As a nurse, she had developed some type of
    allergy/infection and had her eyes examined at the medical school. She
    was given a prescription from the autorefractor "to get her by" until
    she could wear her contact lenses again. Despite the fact that she had
    worn the eyeglasses for nearly one year, she still had a manifest
    refraction of -2.50 in my office.

    The take home message is that the autorefractor was capable of a 5
    diopter magnitude error. This is why it is important to check the
    results. On the other hand, the standard deviation is probably closer
    to +/- 0.50 diopters.

    The other message for "Otis fans," is that over-minusing a patient by 5
    diopters did not increase the patient's myopia.

    DrG
     
    Dr. Leukoma, Jun 7, 2005
    #3
  4. John Yasar

    John Yasar Guest

    Oh I see, I think this is when I had my last exam 2 years ago I had to
    look through a different device in a seperate room where my doctor came
    and looked from the other side and said hmm you have some slight
    refraction error but let's go to the office and look into it.
    This is unbelievable!!!! -5.00 overprescribed!!!
    Kind of worried me, I am wondering how much could the deviation be from
    my real refraction in my recent military test.
    I am convinced that this entirely depends on the person and his/her
    eyes. Meaning the "staircase" issue. I think I am one example where my
    refraction didn't change, that is of course if the autorefractor was not
    deviated by a huge magnitude.



    --
    PV2 Yasar, M
    U.S. ARMY
    AH-64D "Armt Dawg"
    A Co/602d ASB/2ID/EUSA - South Korea
    Tuesday, 07 Jun 2005 / 22:14:42 Korea Standard Time (+0900)
     
    John Yasar, Jun 7, 2005
    #4
  5. Interesting. I've always used the term "manifest" to specify a
    subjective refraction without cycloplegia and still do. "Subjective" to
    me means refraction via a phoropter with or without cyclo, while
    "cycloplegic" means just that. Guess I'm an old term too...

    w.stacy, o.l.d.
     
    William Stacy, Jun 7, 2005
    #5
  6. John Yasar

    drfrank21 Guest

    I've always specified manifest "wet" (obviously for cyclo) and
    manifest "dry" to avoid any confusion. I'd bet that if you polled
    10 O.D.'s you'd get 10 slightly different answers regarding
    these terms.

    frank
     
    drfrank21, Jun 7, 2005
    #6
  7. How accurate is the autorefractor at determining the cylindrical
    correction? Close to 100%?
     
    silverblue001, Jun 8, 2005
    #7
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