I don't recall anyone saying "clear." "Virtually clear" I have said repeatedly, as has Judy.Originally Posted by MikeAurelius
I don't recall anyone saying "clear." "Virtually clear" I have said repeatedly, as has Judy.
I'm Andrew Hamm and I approve this message.
ISO Standard 13666 says
When the ISO and ANSI define upper blue light or UV between 380 and 400 nm consider acceptable why should blue light in the visible range be eliminated.
Does not make sense.
Which means precisely nothing, Andrew.
almost [= practically]:
- Virtually all the children come to school by bus.
- He was virtually unknown before running for office.
This debate is pretty silly on the face of it.
The lens being talked about is either
A) Clear
or
B) Not Clear
The picture that Judy posted "clearly" (pun intended) shows that it is indeed B) Not Clear.
So, theory proven, let's move on, shall we?
Deleted.
Last edited by Judy Canty; 10-01-2015 at 10:02 PM.
While I absolutely, positively, couldn't possibly care less about your personal opinion of me - I never called you a liar. For you to insinuate such is indeed the epitome of unprofessional. Now, with that settled, what I HAVE done is call a spade a spade.
This lens is not clear - period. To represent it as such is misleading - it is as simple as that. And that's OK, since none of the other blue sucking lenses are clear either. But it is important to call it out for what it is, and what it is not. It is of critical importance to know, understand, and be able to effectively illustrate that difference to our patients. THAT is our professional duty. If you've never had the opportunity to listen to a patient unload about the indoor tint in their photochromic lenses (nope - not clear), or even better their yellow computer lenses (which made them physically ill) that this or that doc said were the best thing for their eyes - it's a treat, and highly recommended.
Wishing you all success in your business. In the mean time, I am still researching the actual medical need - if indeed any whatsoever - for any of these type of tinted/visible light absorbing lenses. I appreciate the discussion on that topic here so far.
Deleted.
Last edited by Judy Canty; 10-01-2015 at 10:03 PM.
+1
The lack of professional collegiality on this board is the reason I posted so rarely until recently. I could no longer defend Optiboard's discussions as professional when they were being described as "nut jobs" and "wackos" or just plain "rude". Sadly, most members seem to enjoy it. It has changed greatly since I joined in 1995.
It's interesting really - it seems to many of us as well that a marked decline in the quality of science based information concerning lens technology has occurred. Particularly when a few stand to make a profit from selling such products.
But - enough about all that "silliness".
Back to the discussion at hand in this thread: I'm still very interested in learning more about ongoing studies pertaining to short wave visible radiation, specific electronic devices, how they radiate in different environments, and precisely how or if they pose any measurable potential for retinal damage to human eyes. What are the frequencies? What is the energy level? How does the radiation differ across different devices? How can we scientifically determine which devices might be more or less problematic? What can patients do to simply turn the offending frequencies down on their screens on their own? Are expensive "blue busting" lenses their only hope? And how does any exposure to sunlight's full spectrum factor into the equation?
Discuss...
As an interesting side note - on the way out for lunch this afternoon, I picked up a segment through NPR and Science Friday about reproducing data in scientific testing. In particular, how initial conclusions drawn from singular or limited testing can produce a given result (and not surprisingly if there is any monetary bias involved). But that when other peers attempt to reproduce the same - they are unable. Certainly worth a listen to the podcast. And one of the many reasons I remain highly dubious of any of these particular lenses currently. A link to the podcast of the segment if any are interested in having a listen. Some compelling content to be sure.
Putting scientific research to the test
One of my faves from NdGT: “The good thing about science is that it's true whether or not you believe in it.” I'm always open to having my impressions and opinions changed. But you have to provide solid evidence first - and that almost never comes from the desk of the marketing department. :)
(I'm copying this from the Luzerne thread because I'd like some feedback from anyone who has some moderate to strong Rxs in one of the blue reflecting lenses (Prevencia, Recharge, BlueProtect or TechShield sorry for the duplication)
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.)
Therefore Polycarbonate is not fully covering up to 400 nm.
Thanks ml43, interesting.
As far as I can see the cutoff is also a notch below the 400 nm mark which indicates that roughly it is also at the 380 nm mark.
Therefore Polycarbonate is not fully covering up to 400 nm. The barely visible and now dangerous blue light starts at 380 nm and there is no protection unless you have the yellow tinge to neutralize it.
Chris Ryser wrote:
I own one of the fanciest spectrometers and have never even put a polycarbonate lens through it.
I don't quite understand this. Do you not have access to various lens types like polycarbonate? I would love for you to run a spectograph on some lens samples and post them. I will send you samples. I'm particularly interested in the graphs on uncoated poly, AR poly, and blue reflection poly, as well as the same 3 types of trivex lenses. I'll send you the six samples if you'll post the results. Thanks.
I will post a copy of the reading right here on OptBoard.
That would be nice and I will post a copy of the reading right here on OptBoard.
You can get my address of my website.
Or you could go to Opticampus...http://www.opticampus.com/tools/transmittance.php
RT
Wow, nice clean graphs. Maybe too clean. I'm always a bit suspicious when I see 0.00 or 100% anywhere, but will send Chris some real lenses to test on his machine. Should get some results pretty soon. I'll ship out some lenses Monday.
With all this discussion on this blue light absorbtion on the AR coating
With all this discussion on this blue light absorbtion on the AR coating I have come to the conclusion that the absorber could or must be contained in the Hydrophobic coating on top of the AR coating and not in the coating itself.
In order to reflect the violet-blue light and or absorb it at the same time, the absorber must or can be right on top of the surface. We will start a litttle project to find out.
I'm not 100% clear on the fine differences between mirrors and AR coatings, but I do know that anti-reflection coatings work on interference by diffraction at multiple interfaces of different materials in a "Stack" of coatings, each layer causing destructive and/or constructive interference based on the 1/2 wave or 1/4 wave thicknesses of thin films.
None of these work primarily by absorption, which function is left to the lens substrate itself. The hydrophobic top coat I think is just a "stuff" repellent (including water) film that really has no particular reflection or absorptive qualities itself.
diffraction interference is interfering with my brain right now.
Last edited by Dr. Bill Stacy; 08-30-2015 at 06:19 PM.
I am familiar with that, I was the first one that came up with it in 1984 and tried to sell it as "Water Repellent" and nobody wanted it for the first 6 month of its existence.
Then some morning under the shower the idea of "Hydrophobic" hit me. When I got to the office we discussed it and we called all the coating labs we had tried to sell it earlier and told them taht we had a "Hydrophobic" coating for AR coatings to make them easy to clean.
Everybody loved that and we started to sell it like hot cakes, and we were the only ones to have that for years.
We were still the only ones to have that with anti stat and anti fog until E came up their latest invention.
What I am now going to try, is to see if I can incorporate something to make it blue light absorbant.
I'm a bit concerned about the durability of hydrophobic top coats. Your adding a blue absorber to it would make it possible to see how long it takes to wear off. The thing that totally turned me off to Essilor's anti-fog formula was the news that even ONE cleaning removes it, so it has to be re-applied after every cleaning of the lenses. I clean my own glasses at least 2x per day.
Why blue absorbent? What frequency(s)? At what density (how much will you absorb?)
Where is the peer reviewed, and replicated data showing this to be required in humans? Science folks - it's more than vague guesses at the latest protection required from the latest bad thing out to get us. If the data backs it up, we should be easily able to replicate results, and come up with a scientifically and factually based consensus as to what frequencies of visible light can be considered harmful, and at what exposure levels. Further, a determination if cumulative exposure over time is also a factor should be easily made.
I would fully expect, should such data be found, that we could then isolate the particular LED screens, both by manufacturer and specific model and make, that would be the most problematic. From there, a pt could make the best informed decision if they would want to pay for expensive "blue blocking" lenses...or just use the free buttons or software adjustment to attenuate the "bad" blue on their own.
I believe you are forgetting that, just like pharm companies, you must create the demand.
for the record, not to argue for or against,
but the same can be said for selling impact resistant lenses, polarized lenses, anti reflective coatings, titanium frames, etc...
none of these things are to treat or cure a medically proven harmful effect
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