difference between hi index and thin lens?

Discussion in 'Optometry Archives' started by cliveP, Sep 29, 2004.

  1. cliveP

    cliveP Guest

    difference between hi index and thin lens?

    precription card has both options - hi index is ticked?
     
    cliveP, Sep 29, 2004
    #1
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  2. cliveP

    LarryDoc Guest

    As you increase the index of refraction, a lens of a given power and
    diameter will decrease in thickness. High index lenses are a benefit in
    higher power prescriptions, especially minus powers.

    So, hi index/thin imply the same thing.

    But you can also make a lens of a given power and diameter thinner by
    decreasing the center thickness while maintaining the same curves. At a
    certain point, the "thinness" of the center causes the lens to break.

    A thinner designed lens of a lower index is better suited for lower
    power lenses.

    --LB

    --
    Dr. Larry Bickford, O.D.
    Family Practice Eye Health & Vision Care

    The Eyecare Connection
    http://www.eyecarecontacts.com
    larrydoc at eye-care-contacts dot com (remove -)
     
    LarryDoc, Sep 29, 2004
    #2
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  3. cliveP

    cliveP Guest

    As you increase the index of refraction, a lens of a given power and
    So a "thin and lite lens" 1.6 for a -5.5 precription is ok then?
     
    cliveP, Sep 29, 2004
    #3
  4. cliveP

    LarryDoc Guest

    Dear (oh dear) Robert,

    Some of us DO write sensible recommendations below the optical Rx, often
    based on patient's priorities. So it's the "almost always ignore" part
    that got to me. I know, sometimes you must see some pretty silly stuff
    written down there ;-)

    Of course you pragmatic, ethical and knowledgeable opticians---you know
    that subset of your profession--- can certainly help to zero in on the
    best spectacle optics for the patient's needs.

    Best regards,

    LB
     
    LarryDoc, Sep 30, 2004
    #4
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