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Thread: prevencia's true colors

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    prevencia's true colors

    Would someone mind taking a pic of the crizal prevencia AR coating that displays the yellowish purple colors very clearly?

    Thanking you in advance,

    Eric

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    It doesn't look anymore "yellow" than normal crizal, but it has an added purplish hue reflex as well as the normal green.

    Sorry don't have a pair but maybe next time they come in.

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    Eyes eastward... Uilleann's Avatar
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    Quote Originally Posted by chaoticneutral View Post
    Would someone mind taking a pic of the crizal prevencia AR coating that displays the yellowish purple colors very clearly?

    Thanking you in advance,

    Eric
    Can your E rep get you a sample? Like all tinted/mirror lenses, it will likely look different under different light sources. Best to view it in person.

    (Apart from the horrific temple "adjustment" on the pair shown, here's one example showing the reflex and yellow nature of the lenses: http://www.walkersopticians.co.uk/wp...2/DSC07150.jpg). Google has several others as well...

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    The rep just came in with a ton of POP. There's a display with the avance and prevencia as full size lens blanks. I hate to be a nay sayer (that's not true I revel in nay saying) but the demo lenses look like the typical green hue of avance and the blue of sapphire. The first few pair of prevencia we got in our office had a yellowish hue on top of the purpley reflection. maybe im just crazy. That's what my cheerios tell me, but who listens to cereal?

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    Master OptiBoarder LENNY's Avatar
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    I see it like 2-3% yellow in the material plus really purple reflection.

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    Master OptiBoarder opty4062's Avatar
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    I wear them. I see the yellow cast occasionally and have tried to photograph it before but had no luck. Tried just now and got this...Click image for larger version. 

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    eta: picture
    Last edited by opty4062; 12-12-2014 at 04:20 PM.

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    I got a demo pair and compared it with another labs blue light blocking AR, and both, surprise! surprise!, had a very blue/purple hue to them lens. I'd guess the yellow and green you're seeing is the result of the blue waves being reflected back. (Pure speculation honestly but I'm running with it :^) )
    As for a pic I tried and the only thing I could get looked just like Opty's pic.

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    Quote Originally Posted by Boldt View Post
    I got a demo pair and compared it with another labs blue light blocking AR, and both, surprise! surprise!, had a very blue/purple hue to them lens. I'd guess the yellow and green you're seeing is the result of the blue waves being reflected back. (Pure speculation honestly but I'm running with it :^) )
    As for a pic I tried and the only thing I could get looked just like Opty's pic.
    Have a pair in Recharge... Shows up as slightly more brownish, to me, but they are combined with Trans-7 in brown, which I suppose might be cutting down on the yellow.

    Question-- theoretically, could similar benefits be seen simply by combining a standard AR with a yellow 2-3%, or is there a unique property to blue-blocking ARs that makes them more effective?

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    I could see that making them more brown than yellow, but I don't know much about recharge.
    The way I understand it, no. The way it was explained to me is that there is a layer that both absorbs and reflects the light at the 400-450nm range. While the yellow tint would let it pass through like any other tint. With most AR's that are not blue light blockers (the exception is some with the basic HEV filter and of those I only know about RB Tech) all they really do is disrupt the light as it passes through the lens, letting more through and there by reducing glare.
    Hope I help you out with this. I've just started learning about this over the past year, so I may have some wrong information here.

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    Eyes eastward... Uilleann's Avatar
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    Quote Originally Posted by Browman View Post
    ...Question-- theoretically, could similar benefits be seen simply by combining a standard AR with a yellow 2-3%, or is there a unique property to blue-blocking ARs that makes them more effective?
    Herein lies the problem. There is absolutely no agreement on what specific frequency or frequencies of light to attenuate, nor how far to attenuate said frequencies. Further, every manufacturer seems to have their own particular interpretation of "blue light", and how they choose to "manage" it varies wildly.
    It's the wild wild west...of blue light!

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    Blue Jumper It's the wild wild west...of blue light! ..........................

    Quote Originally Posted by Uilleann View Post
    It's the wild wild west...of blue light!

    I would love to measure these lenses with my spectrometer and find tons of blue light transmitted.

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    I have personally tested recharge, prevencia, and blue tec with a high intensity blue light and they do ALL block alot of the blue light with blue tec by far blocking the most. They say in all of their literature that they do not attempt to block all the Blue light just the higher intensity portion. I feel they do perform as advertised Chris.

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    Quote Originally Posted by golfnut View Post
    I have personally tested recharge, prevencia, and blue tec with a high intensity blue light and they do ALL block alot of the blue light with blue tec by far blocking the most. They say in all of their literature that they do not attempt to block all the Blue light just the higher intensity portion. I feel they do perform as advertised Chris.
    I found completely the opposite. There are sources for the full 400-500nm spectrum lights and the only one that effectively blocks most all of the light transmission is BlueTech's yellow pigmented lenses. The others have gaps and allow for the light to pass through with ease. Gimmicks.

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    Quote Originally Posted by racethe1320:498307
    Quote Originally Posted by golfnut View Post
    I have personally tested recharge, prevencia, and blue tec with a high intensity blue light and they do ALL block alot of the blue light with blue tec by far blocking the most. They say in all of their literature that they do not attempt to block all the Blue light just the higher intensity portion. I feel they do perform as advertised Chris.
    I found completely the opposite. There are sources for the full 400-500nm spectrum lights and the only one that effectively blocks most all of the light transmission is BlueTech's yellow pigmented lenses. The others have gaps and allow for the light to pass through with ease. Gimmicks.
    you are welcome to your opinion but I have seen it in front of my eyes and know without a doubt they block at least percentages of the blue light. I do agree that blue tec by far blocks the most but the other two DO block a portion of the blue spectrum! If anyone out there doubts it test it for yourself and you will see that seeing is believing!

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    Quote Originally Posted by golfnut View Post
    you are welcome to your opinion but I have seen it in front of my eyes and know without a doubt they block at least percentages of the blue light. I do agree that blue tec by far blocks the most but the other two DO block a portion of the blue spectrum! If anyone out there doubts it test it for yourself and you will see that seeing is believing!
    "Crizal® Prevencia™ lenses deflect harmful Blue-Violet light by 20%"
    from the horses mouth. I never believe the hype. Is it still a niche lens for people with macular degeneration and budding cataracts or has been accepted as the end all be all antireflective coating for generation Z and the Millennials

    Click image for larger version. 

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    Quote Originally Posted by chaoticneutral View Post
    "Crizal® Prevencia™ lenses deflect harmful Blue-Violet light by 20%"
    from the horses mouth. I never believe the hype. Is it still a niche lens for people with macular degeneration and budding cataracts or has been accepted as the end all be all antireflective coating for generation Z and the Millennials

    Click image for larger version. 

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    While I believe without a doubt these products work as they are advertised, that does not mean I believe completely the therapeutic effects are definitely there. Only time and lots of trials would be able to prove that. I only stand by the fact that they do indeed block blue light in various degrees. Jmho

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    Master OptiBoarder OptiBoard Gold Supporter Judy Canty's Avatar
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    Attachment 11606I have and wear both. The coating does block a small percentage of blue light and BluTech blocks significantly more though the darker tint is more noticeable. The niche is larger than only those with budding retina issues. The protection makes a difference for those who spend a large amount of time using a computer, video games and other similar digital devices. We are literally bathing in blue light since the advent of CFLs in our homes.
    I would suggest you all bring your lens and coating samples with you to VEE, VEW or SECO and test them yourselves. There were a couple of companies demonstrating blue light testers who were more than happy to allow us to test BluTech and BlueScreen at VEE last year. We were impressed with the results. JMHO.

    BluTech (left or top) BlueScreen (right or bottom)
    Last edited by Judy Canty; 12-13-2014 at 09:05 PM.

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    Master OptiBoarder opty4062's Avatar
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    Personal experience with wearing the prevencia lenses, blue light blocking at whatever level it does...I have gone from needing tears 6+ times per day to twice, at waking and at bedtime. My eyes are not red and fatigued by 3pm on a work day as they were this time last year.

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    I can try to get a pic of our prevencia demo. ..for you to view. My observation was mostly the purple. "Hue". ..I've only had 2 patients complain about the cosmetics and asked to be switched to an avance style ar..
    Personally I show all my patients the demos to show the purple hue to make sure they are aware of it prior to purchase ..

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    Here is the spectrometer graph of a real blue - blocking lens:
    Attached Thumbnails Attached Thumbnails OMS Blue-Blocker070314.jpg  

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    so if there's a yellow ish colour to them it does indeed mean that some blue light is being blocked.

    this does not make selling them as 'blocking out harmful blue light' ethical in the slightest. the problem i have with these lenses isn't their properties - it's the claims of reps and dispensers...

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    Quote Originally Posted by standarduck View Post
    so if there's a yellow ish colour to them it does indeed mean that some blue light is being blocked.

    this does not make selling them as 'blocking out harmful blue light' ethical in the slightest. the problem i have with these lenses isn't their properties - it's the claims of reps and dispensers...
    I made a pair for myself, and looking at a laptop with a cool white screen, then raising the gls you can easily see the screen turn a nice white temp.

    Its all we sell here now. as of today me and the optician have sold 45 this month. :)

    We did have a special older pt come back saying that everyone at Thanksgiving dinner asked her if she had a black eye... shakes my head... said that it was all they talked about;... ok... back to avance you go.

    The purple hue is kinda iridescent with a 2nd reflection of the green like avance. Im assuming that the stack is purple-green LENS green-purple ( green being the layer against the lens surface and the purple being top layers.

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    Quote Originally Posted by Uilleann View Post
    Herein lies the problem. There is absolutely no agreement on what specific frequency or frequencies of light to attenuate, nor how far to attenuate said frequencies. Further, every manufacturer seems to have their own particular interpretation of "blue light", and how they choose to "manage" it varies wildly.It's the wild wild west...of blue light!
    You hit the nail on the head... compare a similarly tinted lens with a blue reflective AR and I doubt you would see any difference.

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    Fundamentally, any lens that blocks blue effectively will have a yellow cast, and its ability to block blue will be directly related to the degree of that cast (its simply a principle of the color wheel, anytime I effectively block one color its Complimentary (opposite) on the spectrum will come through to a larger degree. The damaging rays of of Short Wave Blue are not fully blocked by a yellow, it must be a yellow orange to cover the full spectrum of damaging blue light.

    Historically we have had fluorescent lights now for over 40 years, and the older fluorescent lights put out 10x the amount of SWB than the newer full spectrum bulbs and 15X the older incandescent, and vastly more in lumens than any computer monitor or cel phone does.

    No one advocates full spectrum bulbs for the health benefits (though they do offer other benefits), no one uses the true Yellow-Orange to cancel out all SWB, and NO one has compared their product to a simple yellow tint and a blue reflective AR. And no one has reported a rash of AMD cases because of simple fluorescent bulbs still common in the workplace. Simply put the whole blue light thing as a health benefit is hokey.

    However there is a benefit in contrast that we can document.

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