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Thread: Fresnel Press-On Prism

  1. #1
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    Confused Fresnel Press-On Prism

    Hello all. I have a patient that I am attempting to fit with a press-on prism. It needs to be a plano Diopter, 6 base out. I used to get them from Hilco, but seemingly all they have are press-on diopters - no prism. I know 3M was making them, but can't seem to find a distributor. Does any of you know where I may purchase what I seek, even if it is a different brand?

    Thanks in advance.

    OD

  2. #2
    Master OptiBoarder
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    Hilco has a 6D press on prism, part number Part #1031655

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    OptiBoard Professional KrystleClear's Avatar
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    You should be able to order a 3M fresnel prism through your lab. Unless my Hilco catalogue is out of date, you can still order fresnel press-ons through them. However, my lab (Luzerne) gets them for us for a few bucks cheaper.
    Last edited by KrystleClear; 08-24-2021 at 06:38 PM.
    Krystle

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    OptiBoard Professional OptiBoard Silver Supporter Optical Roy's Avatar
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    Roy W. Jackson, Sr. ABOC

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    OptiBoard Professional KrystleClear's Avatar
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    Quote Originally Posted by Optical Roy View Post
    One of our doctors would like us to keep some fresnels in stock and wants me to look into ordering directly from the supplier - but he wants to know if we can return them before the "expire" if they don't get used? I would imagine they probably wouldn't allow that...?
    Krystle

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    OptiBoard Professional OptiBoard Silver Supporter Optical Roy's Avatar
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    Quote Originally Posted by KrystleClear View Post
    One of our doctors would like us to keep some fresnels in stock and wants me to look into ordering directly from the supplier - but he wants to know if we can return them before the "expire" if they don't get used? I would imagine they probably wouldn't allow that...?
    I keep 2, 3, and 4 base in stock. Not aware of any expiration date and have not seen one yellow like an rx lens, maybe by the way they are packaged. They do overnight so that shouldn't be as much of a concern, but you would need to ask them directly on that, they are very helpful. I have used a ton of them as I was a low vision dispenser for years.
    Roy W. Jackson, Sr. ABOC

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    Master OptiBoarder optical24/7's Avatar
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    I always bought direct ( fresnel-prism.com). I kept every prism from 1-20D and a 30D and 40D for the rare Hemianope. I’ve never seen one get brittle or discolor. Warning about going direct; they will kill you on S&H. They aren’t worth dealing with if you are going to onesie or twosie order. Check with your lab on costs for those really small orders.

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    OptiBoard Professional KrystleClear's Avatar
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    Quote Originally Posted by optical24/7 View Post
    I always bought direct ( fresnel-prism.com). I kept every prism from 1-20D and a 30D and 40D for the rare Hemianope. I’ve never seen one get brittle or discolor. Warning about going direct; they will kill you on S&H. They aren’t worth dealing with if you are going to onesie or twosie order. Check with your lab on costs for those really small orders.
    Got ya! I am just trying to see if ordering direct will save us anything, if at all, and shipping charges are a factor.
    Krystle

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    It was cheaper for us to get from our local lab due to shipping. We don't stock them because we don't use them often.

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    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    Quote Originally Posted by OpticalDinosaur View Post
    Hello all. I have a patient that I am attempting to fit with a press-on prism. It needs to be a plano Diopter, 6 base out. I used to get them from Hilco, but seemingly all they have are press-on diopters - no prism. I know 3M was making them, but can't seem to find a distributor. Does any of you know where I may purchase what I seek, even if it is a different brand?

    Thanks in advance.

    OD
    I think a definition of just what a prism diopter is, is in order.

    prism diopter

    The unit of measurement of the deviation of light in passing through a prism, being a deflection of 1 cm at a distance of 1 m. ... (05 Mar 2000) ..

    more:
    https://www.encyclo.co.uk/meaning-of-prism_diopter

    A lens focuses light whether real (plus power) or imaginary (minus). A prism deflects light so there is no focused power in a Fresnel Prism. It is just a prism diopter value.

    Someone smarter than me may want to clarify my post.

  11. #11
    OptiBoard Professional KrystleClear's Avatar
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    Upon setting up an account with Fresnel-prism.com and price comparing, it's still cheaper to go through our lab, and fresnel-prism.com does not take returns as there is apparently an expiration date on them.
    Krystle

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