Difference between eye testing machine and eyeglass lenses?

Discussion in 'Glasses' started by Guest, Sep 15, 2004.

  1. Guest

    Guest Guest

    What is the physical difference between the optics you look through
    during the "which is better" objective part of an eye exam and the
    optics used in eyeglass lenses?

    Am I correct in assuming that multiple lenses are used in the testing
    Guest, Sep 15, 2004

  2. ....
    Rishi Giovanni Gatti, Sep 15, 2004
  3. Guest

    Otis Brown Guest

    Dear Rishi,

    Mike is right. Measurements in a darkened room looking
    through the small aperture of a phoropter can produce
    profoundly different results that the results
    you get if you use a trial-lens kit and a Snellen
    with room illumination -- under DMV test conditions.

    I have talked to one man on "i-see" who could pass
    the DMV with 20/30, yet some "over-prescriber" had
    given him a -1.75 diopter lens. Fortunately he
    rejected this powerful minus lens, and always
    passed the DMV.

    Yes, you should check your own "free space" Snellen,
    for fear of getting "over prescribed".

    Thanks for the advice and suggestion, Mike.


    Otis Brown, Sep 17, 2004
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