# Optical Forums > General Optics and Eyecare Discussion Forum >  prevencia's true colors

## chaoticneutral

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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## Tallboy

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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## Uilleann

> 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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## chaoticneutral

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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## LENNY

I see it like 2-3% yellow in the material plus really purple reflection.

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## opty4062

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...

eta: picture

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## Boldt

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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## Browman

> 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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## Boldt

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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## Uilleann

> ...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!   :Bounce:

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## Chris Ryser

> *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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## golfnut

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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## racethe1320

> 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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## golfnut

> Originally Posted by golfnut
> 
> 
> 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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## chaoticneutral

> 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

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## golfnut

> "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


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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## Judy Canty

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)

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## opty4062

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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## cecstephen

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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## Chris Ryser

Here is the spectrometer graph of a real blue - blocking lens:

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## standarduck

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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## Slim

> 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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## sharpstick777

> 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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## sharpstick777

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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## Slim



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## golfnut

> 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.


Not true. I have cpf tinted lenses here and have used a blue light side by side and the tinted lenses DO NOT perform the same. Also, let's clarify, they  FILTER OUT the Blue light, not block it. They all claim to allow SOME blue light through. Once again, don't drink the kool-aid, make some for yourself and test the lenses for yourself.

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## Chris Ryser

> Not true. I have cpf tinted lenses here and have used a blue light side by side and the tinted lenses DO NOT perform the same. Also, let's clarify, they  FILTER OUT the Blue light, not block it. They all claim to allow SOME blue light through. Once again, don't drink the kool-aid, make some for yourself and test the lenses for yourself.



It is all about how much Blue Light in a  dangerous form or otherwise, comes out at the rear end of the lens...............and what is transmitted to the retina.

If you send Blue Light it into the lens, and it comes out again, the claims are just money making ones and will do no good to anyone that paid the price for them.

Maybe the AR coating is reflecting a minimum of blue but what counts is what come out the lens on the back.

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## Tallboy

Chris they say it filters out the harmful wavelengths of Blue light that  contribute to retinal cell death, while leaving the helpful blue light  wavelengths that help us see well and regulate circadian rhythms.

At least that's what they say makes Prevencia different.

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## chaoticneutral

well played slim, that's the same pop display the rep dropped off.  I was as excited as a fat kid rollin up to a cake shop when I saw it, and I felt terrible letting the rep know that it looked like sapphire. she said I'm just the messenger.  I walk by the display 1000 times and look at it every time hoping for a different color but it doesn't look purple. I think maybe im color blind? It sucks getting old

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## golfnut

> well played slim, that's the same pop display the rep dropped off.  I was as excited as a fat kid rollin up to a cake shop when I saw it, and I felt terrible letting the rep know that it looked like sapphire. she said I'm just the messenger.  I walk by the display 1000 times and look at it every time hoping for a different color but it doesn't look purple. I think maybe im color blind? It sucks getting old


So you just want it to be more purple?  I would actually prefer it to be just like the Sapphire but it seems too purple to me?

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## Uilleann

> 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.


You know...there are these cool magic buttons on _EVERY SINGLE LCD SCREEN MADE_ right...and they do the _EXACT SAME THING_.

For _FREE_.

And if the adjustment buttons are too 1980s for a given user, you can always adjust the color balance easily in any computer's GPU settings.  The same holds true for laptops, tablets, & mobiles.

What kills me is that the first time anyone steps outside on a sunny day, that all the hand wringing over "intense blue light" was completely for naught as you are instantly subjected to orders of magnitude more of the same.

But hey - if it sells more lenses...go nuts!

 :Bounce:

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## golfnut

> You know...there are these cool magic buttons on _EVERY SINGLE LCD SCREEN MADE_ right...and they do the _EXACT SAME THING_.
> 
> For _FREE_.
> 
> And if the adjustment buttons are too 1980s for a given user, you can always adjust the color balance easily in any computer's GPU settings.  The same holds true for laptops, tablets, & mobiles.
> 
> What kills me is that the first time anyone steps outside on a sunny day, that all the hand wringing over "intense blue light" was completely for naught as you are instantly subjected to orders of magnitude more of the same.
> 
> But hey - if it sells more lenses...go nuts!


That's why they offer an outdoor version as well!  You could say these same things about a ton of things out there..as in any kind of gadget or gizmo that is supposed to enhance our life!  As far as selling more lenses because of this.. We are going to sell lenses anyway and most of the time they ate going to have some kind of AR coating so why not get the extra advantage of the filter?? But you probably don't believe in AR coating or uv filters or freeform lenses either since you can't quite quantify the actual benefits?We educate the pt and let them decide if it's important to them!

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## AngeHamm

> well played slim, that's the same pop display the rep dropped off.  I was as excited as a fat kid rollin up to a cake shop when I saw it, and I felt terrible letting the rep know that it looked like sapphire. she said I'm just the messenger.  I walk by the display 1000 times and look at it every time hoping for a different color but it doesn't look purple. I think maybe im color blind? It sucks getting old


I don't think it looks like Sapphire at all. Sapphire is a much lighter blue reflex color than Prevencia's purple-blue. And I don't see the noticeable yellowing effect with Sapphire at all.

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## Jason H

> Not true. I have cpf tinted lenses here and have used a blue light side by side and the tinted lenses DO NOT perform the same. Also, let's clarify, they  FILTER OUT the Blue light, not block it. They all claim to allow SOME blue light through. Once again, don't drink the kool-aid, make some for yourself and test the lenses for yourself.


 Not sure about this. Although the yellow cast certainly absorbs blue light - the point of the blue shimmer on the lens ought to be the blue light being reflected away. But that's a small thing. Hard to believe your retinas will burn out from blue light exposure. But it does seem to be useful symptomatically. People use computers 8, 9, 16 mabye more hours in a day. If it helps - thats reason enough to reccomend it. Just not ready to panic over it. I have 2 sons who are computer programmers - they aren't interested in solving problems they don't have.

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## Sledzinator

This sounds interesting. I wonder if it will leave and residual color?
http://www.visionmonday.com/technolo...elength-light/

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## Slim

> You know...there are these cool magic buttons on _EVERY SINGLE LCD SCREEN MADE_ right...and they do the _EXACT SAME THING_.
> 
> For _FREE_.
> 
> And if the adjustment buttons are too 1980s for a given user, you can always adjust the color balance easily in any computer's GPU settings.  The same holds true for laptops, tablets, & mobiles.
> 
> What kills me is that the first time anyone steps outside on a sunny day, that all the hand wringing over "intense blue light" was completely for naught as you are instantly subjected to orders of magnitude more of the same.
> 
> But hey - if it sells more lenses...go nuts!



yes I do know... Im a professional Photograper.  Im not color calibrating all the screens at work... but did think about it lol...

Im selling AR at over 80% personally, so why not sell the Prevencia, its the same price to our customers, plus I am getting 10$ a pop promo...bank!

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## Slim



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