What exactly is crizal sunshield, and why would you use it over another AR?

[Bobbus]

Is there any reason to use crizal sunshield on prescription sunglasses instead of another AR such crizal avance?

I have heard that sunshield is usually applied to the back of the lens and not the front, now since scratch resistance is usually gained from an AR coating, this does imply that a lens with this coating would have no scratch resistance on the front, which would be a bad thing.

According to the crizal website sunshield is available in the following colors: black, gray, gray-green and brown

So would it be safe to say this is basically a colored crizal avance that is only applied to the back of the lense and not to the front, providing the disadvantage of no scratch resistance on the front of the lens?

Would anyone recommend using this?

[edKENdance]

Never heard of it. US only?

[Bobbus]

They like to use different names for the same products in the US and European markets, which is annoying, but sometimes there are differences. The ABBE values for their 1.60 lenses is different in different markets, for example. 36 for the US and 41 for Europe.
Avance = Forte
Sapphire (blue avance) = ??
I think Crizal SunShield is probably "crizal Sun" in Europe http://www.essilor.co.uk/Lenses/trea...CrizalSun.aspx

[rbaker]

http://www.essilorusa.com/EN/aboutus...d%20Launch.pdf

[Randle Tibbs, ABOM]

The scratch resistance is not actually gained from the A/R itself but from the hard coat that is applied along with the A/R stack which is basically the hard coat that is used for non A/R lenses as well, so you will have a front surface hard coat.

[AngeHamm]

SunShield is Crizal's sunglass-specific AR coating. It is a backside AR+scratch coat, with the front side scratch coat only. Same warranty as Avance. They also offer a SunShield with Mirror combo which is quite nice.

I don't know why anyone would do a frontside AR on a sunglass lens, though I know one optician who insists on doing it. The whole point of sunglasses is to increase the lens's opacity for light coming in through the lens, right? Why would you add a product that makes the lens more transparent?

I was told by my Essilor rep last week that the Xperio brand is switching from polarized-only to polarized with SunShield later this year.

[nicksims]

I've used it for myself and like it. While I agree with you, AngeHamm on the technical side, I just don't feel a difference while wearing either the backside only or Avance on both front back. Although I won't do this for somebody who wants the feel of a darker lens, I just like how it looks.

[Barry Santini]

Most of my clients who have AR on BOTH sides of their sun (polarized) lenses would not have it any other way. That said, if a person is very light sensitive, or they insist on not seeing their eyes behind the sun lenses, then no AR on the front. And don't forget the smudge issue with AR on Suns!

B

[blindboy]

Crizal Sunshield/Xperio UV provides increased UV protection from reflective UV on the backside of the lens. As mentioned, there is still front side protection (scratch, hydro/oleo, etc.). I am guessing we will see the "Xperio" name go away. There will still be an Essilor polarized lens, but the Xperio UV will be the 'branded' sun lens with back UV and non glare.

[rinselberg]

It always seems to me--albeit I am not anything much of an optical scientist--that there is no reason not to have AR on the front side of a tinted or polarized sunlens, as well as the back side. At least, not any reason that is based purely on the level of light transmission to the sunlens user's retina. If you coat the front side of a tinted or polarized lens with AR, how much would that actually increase the light transmission through the front side of the lens to the user's eyeballs? Wouldn't that number (delta light transmission, delta being the difference between AR-coated and not AR-coated) actually be so small as to be practically insignificant, in terms of the sunlens user's eye comfort?

[uncut]

In the transmittance world, an important factor to consider is the IR spectrum, and not having a AR on the front of the lens will assist slightly with IR blocking. Mirror coating the front is the "king" method of IR blocking.

[Mick]

Essilor's new branding of polarized AR is merging to Experio UV, which is polarized lens with back AR and scratch resist front with all the hydro-oleo top coats. I got a package yesterday with all their propaganda.

[blindboy]

Mick, was your package delivered by an Essilor person, or by a merchandising company, can you tell me?

[Mick]

It was delivered by a Essilor detail rep. Not the regular lab rep.

[blindboy]

Thanks Mick. I know they contracted with an external company to, theoretically anyway, do some merchandising. I had some practices who were supposed to get done, but it seemed like 'drop and go' in many.

[Chris Ryser]

Nice discussion .............................. will make your lenses some more expensive.

Are there any studies published on macular damage through UV reflections from backside only, while there was full 100% absorbance of UV light throughout the lens ?

Could somebody give me a link to anything ?

[blindboy]

Nice discussion .............................. will make your lenses some more expensive.

Are there any studies published on macular damage through UV reflections from backside only, while there was full 100% absorbance of UV light throughout the lens ?

Could somebody give me a link to anything ?

You're right about the cost to the patient increasing. Looks like about a $10USD difference in the practices I've seen. But in some cases it's also more expensive for them to choose UV blocking on the front of their lens.

I'm not smart enough to do the math or rich enough to conduct the study, but there is availability of the back reflectance percentage of UV with (no AR/standard AR/UV absorbing AR). I do believe that there is no "good" amount of UV for eyes... otherwise, why not trumpet "78% UV protection"?

[Chris Ryser]

I can easily absorb 100% UV through the lens with a UV treatment. What would be the reflectance of UV without the AR coating that lets the UV go into the lens to be absorbed ?

[blindboy]

I can easily absorb 100% UV through the lens with a UV treatment. What would be the reflectance of UV without the AR coating that lets the UV go into the lens to be absorbed ?

Sorry, Chris...I don't understand the question. Even when I do, I'm not sure I'd be able to offer an answer, but could you rephrase?

[Mick]

As I understand the UV part of sunshield, and now the various Crizal UV's, the purpose of adding the uv part is to eliminate sunlight from reflecting off the back of the lens into the eye. It's benefit for a close fitting wrap frame I don't get, but dress wear I think I see it's benefit, but I'm not the brightest bulb in the cookie jar.

[blindboy]

As I understand the UV part of sunshield, and now the various Crizal UV's, the purpose of adding the uv part is to eliminate sunlight from reflecting off the back of the lens into the eye. It's benefit for a close fitting wrap frame I don't get, but dress wear I think I see it's benefit, but I'm not the brightest bulb in the cookie jar.

I agree about a tight wrap, although I suppose in theory if there are "any" gaps, there is potential for exposure. And not to be pedantic, but sunlight and UV can be different. Eliminating the sunlight reflection will likely help with some glare ("WHY CAN I SEE MY EYELASHES IN HERE??!!!). Eliminating the UV reflection brings more of a clinical benefit, I think. :)

[CCGREEN]

I just dint understand what there is NOT to understand about Crizal Sun Shield. It's simply TD2 scratch coat front and back side to keep scratches down. A/R back side to keep you from seeing reflections on back of the lens like your own eye (which can easily be seen on a dark shiny surface) or any bright image reflecting to the side or behind you. No A/R on the front side because A/R is made to let light IN. Sunglasses are made to keep light OUT. IMHO that is as simple as it gets.

[blindboy]

I just dint understand what there is NOT to understand about Crizal Sun Shield. It's simply TD2 scratch coat front and back side to keep scratches down. A/R back side to keep you from seeing reflections on back of the lens like your own eye (which can easily be seen on a dark shiny surface) or any bright image reflecting to the side or behind you. No A/R on the front side because A/R is made to let light IN. Sunglasses are made to keep light OUT. IMHO that is as simple as it gets.

But it's not. The backside is also designed to absorb UV, while reducing glare. A standard AR on the backside actually creates more *UV* reflection than a completely untreated backside. So, I think that's the main difference.

[icmor]

But it's not. The backside is also designed to absorb UV, while reducing glare. A standard AR on the backside actually creates more *UV* reflection than a completely untreated backside. So, I think that's the main difference.

Can someone provide a white paper on how much UV is reflected off the back surface of a polarized sun lens into the eye by a non AR coated lens, vs. a standard AR coated lens (Backside only), and UV AR backside coated lens? I'd like to see what the true reduction of UV reflection actually is. Until then, I'm not buying into all the hoopla of this coating. Is the White paper you provide, Essilor's or is it a neutral third party study?

[jpways]

I found Essilor's white paper http://www.crizalusa.com/ECP-Resourc...204%20page.pdf, but then I looked at the studies they cite to see where they are supporting their UV reflectance claim and that would be the paper: Anti-reflective coatings reflect ultraviolet radiation from the Journal of Optometry the full text is available here: http://www.optometryjaoa.com/article...577-5/fulltext. The paper studies clear lenses coated with ARC or not coated with ARC and tinted lenses but not polarized lenses. But what I found interesting in the study was that ARCs performed worst than the uncoated lenses as a side note the paper was published in 2008 so the ARCs tested were Zeiss's Teflon and Gold (Zeiss Gold on the 1.9 Glass that was tested), Crizal Alize, Hoya High Vision, and Polycore's Mxplus (which I have never heard of and while Polycore does list an ARC on their website it is just called Anti Reflective Coating). So, I'd be interested to see if they repeated the study with Purecoat and Super HiVision EX3 vs Avance UV or Sapphire UV whether the results would be as bad as that generation of coatings due to the decrease in reflectance that we're seeing in the current generation of ARCs vs that generation of ARCs (I'm separating the Crizal coatings vs non Crizal coatings because if Crizal's claims are independently verified then I would expect that there would be a statistically significant difference between Purecoat or EX3 and Crizal Avance UV in reflected UV).
Now with polarized lenses I would not expect a significant difference in reflected UV vs. a tinted lens. Remember polarizing filters only allows light through a single plane (in the case of ophthalmic polarized filters it would be the plane of light that is visible to the human eye). Polarization has nothing to do with reducing reflected light so I would expect that if that study also used polarized lenses in addition to tinted lenses the reflectance curves would look virtually the same (allowing for the variations for the material type and lens quality) when comparing similar tint colors individually.