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Thread: Shamir Intermediate Channel Question

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    Shamir Intermediate Channel Question

    I have a patient in a Creation and loves it.

    He is an ER doc and especially appreciates the intermediate width. He charts a lot, but especially depends on the intermediate width when doing procedures in the ER.

    In the same frame with a similar Rx, will he experience a wider intermediate channel in Auto II, Element or Creation?

    OD: +5.00 - 0.50 x 97 2.50 ADD 22 high
    OS: +2.25 - 0.75 x 85 2.50 ADD 22 high

    Would you consider changing him to the new Definity or another lens which many have raved about for it's intermediate performance? Stay with creation or goto digital shamir lens?


    Thanks

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    Bad address email on file k12311997's Avatar
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    Does he need distance? Why not use an Office lens for surgery much wider intermediate than any of the progressives mentioned.

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    He does need distance. Thanks for the suggestion though!

    John

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    One eye sees, the other feels OptiBoard Silver Supporter
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    Amblyopic? Might be nice to have Trivex in front of the left eye, especially if it's a big city ER. All of the lenses you listed are available in Trivex except the Creation.

    IMO, any of the high quality moderate to long corridor PALs will provide intermediate utility if you fit close and accurately. The fixed 18 Auto 2 will probably have the best near utility.

    I've noticed that anisometropes seem to do better with the Varilux lenses.

    OTOH, if it's not broken...
    Science is a way of trying not to fool yourself. - Richard P. Feynman

    Experience is the hardest teacher. She gives the test before the lesson.



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    Patient is not amblyopic and shockingly is wearing the lenses in CR. I was thinking 1.60 for a combo of good abbe and much thinner and lighter weight. Especially since the frame is a bit on the larger size.

    john

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    re: Shamir Intermediate Channel Question

    Either the Element or the Autograph II should have a larger angular field of intermediate vision than the Creation because their progressive optics are on the back surface instead of on the front surface as is the case for the Creation.

    The benefits of the back surface design are greater for a patient with the rx you provided than for an emmetrope.

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    my preferred lens of choice for him would be the Hoya ECP in phoenix(trivex) material. That's the lens I use for most hyperopes.

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    Why would you prefer Trivex since the frame is on the larger size ? Except being a stronger material what other advantage the material Trivex has ? The index is low ( almost same as CR-39 ) and ABBE value is also is not much different than say Hi index 1.60 lens material ! Designwise Autograph II will be a better choice as it has a wider corridor and wider Near vision than Creation and material wise 1.60 index will be a good choice so the lens can be thinner.

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    Trivex has the lowest specific gravity of any material at 1.11, making it the lightest material per unit of thickness. So, in a relatively low Rx, where lens thickness is not a main consideration, Trivex will be notably lighter than CR-39 (specific gravity of 1.32)



    Quote Originally Posted by SANJEEV MAINI View Post
    Why would you prefer Trivex since the frame is on the larger size ? Except being a stronger material what other advantage the material Trivex has ? The index is low ( almost same as CR-39 ) and ABBE value is also is not much different than say Hi index 1.60 lens material ! Designwise Autograph II will be a better choice as it has a wider corridor and wider Near vision than Creation and material wise 1.60 index will be a good choice so the lens can be thinner.
    John Henahan
    Spectrum Eyecare
    www.speceye.com

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    Quote Originally Posted by john-atlanta View Post
    Trivex has the lowest specific gravity of any material at 1.11, making it the lightest material per unit of thickness. So, in a relatively low Rx, where lens thickness is not a main consideration, Trivex will be notably lighter than CR-39 (specific gravity of 1.32)
    Thanks John, So if i do the math and take an uncut round lens of CR 39 and compare it with Trivex i will have 20% more weight if the Dia of both lens is the same. Considering that almost 40% weight of the lens is reduced when you cut it to frame shape ( in minus lens the thickest parts will be at the edge so you are cutting out max weight areas and the reduction in weight could be as much as 50% or even more depending on the frame ) In low powers the avergare weight of each lens will be about 22 grams in CR 39 and about 19 grams in Trivex. After cutting it to shape this weight is going to be 13.2 grams and 11.4 grams giving us a difference of 1.8 grams per lens. If you will use a hi index lens instead you will actually end up with having a thinner and lighter lens than trivex Even comparing with CR 39 the difference in overall weight is not so much as to justify the massive price difference in Trivex and Cr 39 prices. Trivex is a very good material of course but for a full rim frame in relatively low powers CR 39 will do just as well.

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