I just saw Luzerne's TheraBlue lens.

[Dr. Bill Stacy]

Until a blue reflective coating is added, then it will be yellow, for sure.

[Judy Canty]

Until a blue reflective coating is added, then it will be yellow, for sure.

If the lens material is already absorbing blue light, why would you add a blue light reflecting treatment? Gilding the lily? Maxing profit potential? Why?

[Dr. Bill Stacy]

I think the visible blue absorption of these lenses MUST be minimal, or there would be a yellow tint already. If one believes that maximal protection against the blue is needed, that would be by additional yellow tinting and or blue reflective coatings. The only other option is to minimize blue and white coming off the screen (by filters and/or by modifying colors on the display). If one doesn't buy the science of blue protection, fine, why bother with absorbing a tiny amount or any at all? So far I think this lens is a solution to no problem. But I'm keeping an open mind until the spectrophotometry is released.

[farawayC]

Welcome to Otiboard farawayC!!!

SWB = ?

Thanks, Fester. I look forward to being here.

Short wave blue. I think basically interchangeable with high energy visible light (HEV) in the 400-500nm range. Actually, I like the term HEV better because that's an ophthalmological term. Not sure where I picked up short wave blue from.

I'd guess short wave blue, but then he threw in the 250 nm with it which is definitely UV and not visible, so would have no effect on lens color. Maybe that was a typo. I think most modern lenses we are talking about absorb at 250 without additives.

Yes, 250nm was a typo. Meant to say 450nm.

This particular product is a lens material (three lens materials, actually, an ANSI-Z87.1 impact-resistant 1.56, a 1.60, and a 1.67), not an AR coating. It is compatible with a wide variety of AR coatings. And there is no yellow to be seen.

Sorry, I should have made that distinction clear in my post. But, yes, I'm aware that TheraBlue, UV++, etc. are material based absorbents.

[MikeAurelius]

It all depends on where the 50% cut-on point lands. If it lands at 400 nm, the material will be clear. If it lands at 420 nm, it will be yellow. That's pure optics/physics. Especially on an uncoated, untreated lens. There is no way around it.

Look up Schott GG400 and GG420 long-pass filters. GG400 is a clear material, it's 50% cut-on is at 400 nm. GG420 is yellow, and it's 50% cut-on is at 420 nm.

GG400: http://www.edmundoptics.com/optics/o...filters/46422/
GG420: http://www.edmundoptics.com/optics/o...filters/46425/

Tech data is there, including transmission charts.

[igirl]

I refrain from calling them AR coatings because AR traditionally means less reflections, not more. I like to call them what they are, Blue and Violet reflective coatings, AKA mirrors. I know one thing, they all reflect strongly in the visible blue, indigo and violet, as well as the UV, with some reflecting hues more in the blue, others more in the violet.

They are kind of hideous to look at and can be dangerous, as pointed out on www.noviolens.com.

Thank you! I have been making this point for over a year now with manufacturer reps when they call their blue reflecting coatings "AR". When uncoated plastic reflects roughly 10% of light, AR reflects less than 1%, how can you call a coating that reflects 17% of light (I think that is what Prevencia reflects) an AR coating? Putting AR on the backsurface does not make it an AR lens.

[Dr. Bill Stacy]

yes, a case of unintended consequences. good idea, bad execution. they should all come with a uv warning.

[AngeHamm]

Thank you! I have been making this point for over a year now with manufacturer reps when they call their blue reflecting coatings "AR". When uncoated plastic reflects roughly 10% of light, AR reflects less than 1%, how can you call a coating that reflects 17% of light (I think that is what Prevencia reflects) an AR coating? Putting AR on the backsurface does not make it an AR lens.

There is no way Prevencia reflects 17% of light. I'm looking at a sample in my office and it looks approximately as clear as a Super HiVision sample right next to it, just with a selective reflex color in the blue/purple range instead of green.

[igirl]

I will have to go through my marketing pieces from when it was originally launched. The 17% sticks in my head and it was either on one of their original pieces or our rep verbally told us. Looks like a mild flash mirror to me.

[AngeHamm]

The "Prevencia is a flash mirror" trope has been repeated around here a few times. It's not true. I recommend looking at a Prevencia sample and an Avance sample next to each other. The residual reflections are approximately the same, just the color is different. It's similar to Zeiss blue and gold. The gold isn't a "gold flash mirror."

[Dr. Bill Stacy]

The problem here is some people are viewing the blue reflectors in an incandescent environment where there's not much blue to be reflected, so of course they won't see the heavy blue reflections when viewing under daylight or fluorescent lighting where there's so much blue you can't miss it unless you're color blind. Take a pair ove to an open window, or find a fluorescent tube to see the reflection. Or watch the short video on www.noviolens.com to see it for yourself.

[Judy Canty]

Attachment 12274

[Dr. Bill Stacy]

Why would you use a tinted polycarbonate lens in this comparison?

[Judy Canty]

My error. It's a SunSensors.

[Judy Canty]

This is tiresome. Visit our booth at VEW. LP4090. Ask all the questions you like. See the lens in person.

[AngeHamm]

The amount of judgments made about this product by people who haven't seen it is astounding to me.

[igirl]

The "Prevencia is a flash mirror" trope has been repeated around here a few times. It's not true. I recommend looking at a Prevencia sample and an Avance sample next to each other. The residual reflections are approximately the same, just the color is different. It's similar to Zeiss blue and gold. The gold isn't a "gold flash mirror."

I have samples of all Crizal products as well as Hoya and even the new Shamir AR. The Prevencia and Hoya Recharge look like a light flash mirror to me, they just do. We can agree to disagree :) With that being said, I also have a sample of the new blue filtering lens Judy is promoting and think it is very promising and will be what I recommend for those concerned about exposure to blue light.

[AngeHamm]

I have samples of all Crizal products as well as Hoya and even the new Shamir AR. The Prevencia and Hoya Recharge look like a light flash mirror to me, they just do. We can agree to disagree :) With that being said, I also have a sample of the new blue filtering lens Judy is promoting and think it is very promising and will be what I recommend for those concerned about exposure to blue light.

Fair enough!

[Dr. Bill Stacy]

I think I've figured out the discrepancies posted about the blue reflectors.

These lenses have pretty strong reflections off both front and back surfaces, viewed from EITHER side, let me call them primary and secondary, the primary reflection being off the first surface (the one facing the observer) and the secondary being off the second surface the light hits. The primary is usually the brighter image and usually blue. The secondary is usually GREEN, because the first surface has reflected away most of the blue, leaving the remaining wavelengths to be reflected back, and is fainter because it is so attenuated by two passages through the lens substrate.

Now most of us are looking at plano samples of the lenses, where the surfaces are completely parallel and so the reflected images are superimposed and identical in size and shape, so we only see the bright blue primary. The secondary green image is washed out.

However, if the power is moderate to strong, the two curves are dramatically different, so the primary and secondary images are quite different. The flatter surface will generate the larger reflection and will be the most obvious. In the case of a minus lens, the front surface will reflect a bright blue mirror-like image to someone looking at the wearer. For a plus lens, the front surface is very convex and will present a diffuse blue primary reflection that may be not noticeable because it's so diffuse, while the 2nd reflection will be a more conventional looking green reflection, subdued by the substrate but more noticeable than the blue because that back surface is more flat mirror-like.

Now if you flip the minus lens over and look at the back side, the primary is the concave mirror that will form a real inverted blue reflection between the lens and the observer's eye. Very noticeable and potentially harmful. And the secondary reflection will be large but somewhat subdued green reflection. If you flip the plus lens over the flat primary surface will reflect a large bright blue image of the light source, while the secondary will be a small, inverted real green image of the light source.

A lot of the above is an educated guess, but I'm pretty confident that those wearing Prevencia or other blue reflectors will comment and prove me wrong or right. Remember, this all assumes the light source has some blue in it (uncovered window, fluorescent fixtures, etc.)

[Chris Ryser]

Attachment 12274

I would love to see a spectrometer chart on each of these lenses to see how much of the blue light is transmitted into the eye.

Anti reflex does not mean that there is no transmission of direct light.

It transmitts actually up to 9% more light.

[Robert Martellaro]

http://www.google.com/patents/EP2618206A1?cl=en

This appears to be the origins of the technology used in the above mentioned UV/violet/blue absorbing ophthalmic lenses that show very little color, heretofore unprecedented in area of visible-light optics.

The lens can thus cut ultraviolet and visible radiation having wavelengths of 430 nm and shorter, or even 500 nm and shorter, while keeping highly transparent light color.

Note the difference in spectral transmittance graphs from the above, and below. Mitsui may have found a way to increase the the total luminous transmittance, with a sharper high pass cutoff, or the graphs displayed by inventors and/or Mitsui are not highly accurate.

http://www.businesswire.com/multimed.../#.VfmtGbRH1LA

[Judy Canty]

Imagine that.

[AngeHamm]

It's almost as if the people claiming this lens is virtually clear were seasoned optical professionals who know what they're talking about.

[drk]

A solution looking for a problem, IMHO.

[Judy Canty]

drk via your website:

"Finally, some of the newer computer lenses are specifically designed to block the short-wavelength, blue light that is emitted from computer screens. Blue light is associated with glare, eyestrain and potentially more serious long-term vision problems."