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Thread: Iseikonic Lenses

  1. #1
    Luzerne Optical Laboratories
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    Iseikonic Lenses

    Help! I have an Rx requesting Iseikonic lenses.
    Rx: R +3.50-0.50 X 005
    L Plano
    This is being done in Poly in a 45/15 frame, PD 28/28.5. I can't seem to find a formula that will give me curvatures and thicknessCan any one help?

  2. #2
    Master OptiBoarder optical24/7's Avatar
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    If you use a 4 BC OD w/2.8 c.t, and a 8 BC OS w/5.0 ct you'll end up with Mag difference of 2.16% (assuming an 11mm vertex OD, 13mm OS vertex)

    You can drop it to a 2.08% difference subbing trivex on the OS (poly OD). You could further drop the difference by using an asphric on the OD/sph on OS to drop the thickness a tad more (on the OD).

  3. #3
    ATO Member HarryChiling's Avatar
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    For a calculator try this:
    http://www.onlineopticianry.com/isekonic.php
    For the actual calculations try this:
    http://onlineopticianry.com/wordpress/?p=37

    Attached is a spreadsheet that you can use when your off line to calculate an isekonic lens. It works on a Blackberry as well.
    Attached Files Attached Files
    Last edited by HarryChiling; 10-09-2009 at 02:12 PM.
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    OptiBoard Apprentice fagin's Avatar
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    Do you have the corrected visual acuities ? Is the plano lens a balance or pseudo-aphakic ? I have not supplied an Iesokonic lens in the last 13 years of practice with very good reason. I have dealt with this type of Rx many, many times and never had an issue with CRIS, be wary of making life hard for yourself.

  5. #5
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    theory or practice

    Not much point sorting out anisokonia unless symptomatic. If symptomatic then you have to get mapping right - and it is often different to theoretical size differnces. It is likely that there may be other processing problems too - and these will need sorting out eg temporal processing between eyes
    Contact lenses may be better - but pragmatism is the best of all.

    I agree with fagin - don't look for difficulties on this one - correcting anisokonia may be inappropriate - a simple sv lens is inexpensive and worth the risk.

  6. #6
    ATO Member HarryChiling's Avatar
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    If the prescription is calling for it, please use isekonic lenses.
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  7. #7
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    anisokonia

    I'd bet they haven't used eikonometry to determine whether it would help.
    But yes as its prescribed - so it has to be sorted.

    Image sizes and mapping are complex - I'd bet on the prescriber not thinking it through.

  8. #8
    OptiBoard Apprentice fagin's Avatar
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    Quote Originally Posted by HarryChiling View Post
    If the prescription is calling for it, please use isekonic lenses.
    It is the wearer not the prescription that we are catering for, surely ?
    A prescription on its own can't dictate the best form that a correction should take. Why try to address a problem that may not exist ? Lenses are very simple when compared to that most complex thing - the human being..:)

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