How does an autorefractor work?

Discussion in 'Optometry Archives' started by Alistair Barrett, Feb 28, 2004.

  1. I have been set an assignment to do about how an autorefractor works.
    I would be grateful of any help you can give me.
    Alistair Barrett, Feb 28, 2004
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  2. Alistair Barrett

    Otis Brown Guest

    Dear Alistair,

    In order to work properly, I believe that the
    accommodation system must be paralyized with
    a drug to get an accurate reading your
    your refractive status.

    I would be curious about that point, since
    in some cases you can get an error of
    -4 diopters if this is not done correctly
    according to one OD on this site.


    Otis Brown, Feb 28, 2004
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  3. Alistair Barrett

    Jan Guest


    An auto-refractor is never to be trusted accurate.
    It is a helpful and time saving instrument, nothing less nothing more.
    Most of the time accurate which you can tell after you did the normal
    refraction work.
    This instrument is also handy in cases of verbal difficulties to get a quick
    but, in my opinion, rough idea about the amount and type of ametropia.

    Jan (normally Dutch spoken)
    Jan, Feb 29, 2004
  4. Alistair Barrett

    Robert Kopp Guest

    I suppose then it's mainly useful with retardates and other individuals
    who cannot communicate. In the case of language difficulties, it would be
    better to find a translator, even if this is inconvenient.
    Robert Kopp, Mar 1, 2004
  5. Alistair Barrett

    Jan Guest

    Again, the auto-refractor is useful to get a QUIK and ALMOST right objectiv
    view on the amount and type of ametropia.
    In that way it is time saving in "starting" with the subjective measurment
    knowing already what you might aspect.
    The problem, however, is that you NEVER, without a subjectiv measurment done
    afterwards, know if the measurment is the correct one.
    BTW, the objectiv measurment could also be done by a much cheaper instrument
    called a skiascoop but that takes more time and skill.
    In cases of language difficulties it is possible to measure subjectiv by the
    use of Landolt rings (a little gap in the ring pointing in different
    directions in each other ring) without the help of a translater.
    But in this case it is handy to "start" with a measurment done by that
    handy instrument called auto-refractor.
    One important thing to be mentioned is the impossibility to quantify the
    vision aquity by an auto-refractor and this therefore is done afterwards
    while measuring subjectiv.

    Jan (normally Dutch spoken)

    Subjectiv= questioning from the professional and getting answers from the
    patient/client after changing glasses in the trial frame or phoropter.
    Objectiv= no need from the patient/client to respond when measuring.
    Jan, Mar 1, 2004
  6. Alistair Barrett

    Dr Judy Guest

    I assume this is a course assignment and your professors would like you to
    also learn how to research a topic, not just get an answer from a news
    group. Most textbooks on refraction should have a section on auto
    refractors and retinoscopy, your optics text will explain optometers, and
    you could try MedLine or PubMed (or your school library) to look for the
    published articles that describe the development of auto refractors and
    describe how they work.

    Dr Judy
    Dr Judy, Mar 4, 2004
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