Effects of Light-emitting Diode Radiations on Human Retinal Pigment Epithelial Cells In Vitro

November 14th, 2013

Default Re: A Study Shows LED May Damage Human Eyes

It sounds like a commercially funded paper meant to drive sales, just from reading the comments above.

There is some real concern about blue light — anyone who’s had an eye exam from an opthalmologist (medical doctor, not an optometrist) has probably noticed they no longer use the very bright blue light after dilating your eyes to look at the retina — at least where I go (a teaching hospital) for eye exams. Blue photons are are high energy photons compared to anything toward the red end of the visible spectrum — energetic enough, I recall, to knock the occasional electron off a molecule. That’s reason for caution.

‘oogle Scholar, limited to 2013: http://scholar.google.com/scholar?as…ght+eye+damage
Plenty of research going on about this (limited to 2013 just to reduce the total; the papers go way back if you don’t limit the year searched).

My take on this kind of thing is that common sense is scarce enough that doctors do raise concerns — and that industry generally is very eager to teach the controversy, fund wackos on both sides of any issue, and try to delay any action that affects sales of the products that might turn out to have some risk.

Statistical risk is what public health is all about — at least when there aren’t bodies stacked on the sidewalks, most of us never see anyone who’s had any of the statistically risky results. I don’t know anyone with lung cancer, right now; I don’t know anyone with Thalidomide damage now either — though I did when I was young. It’s been a decade or more since I had a friend who got polio, back when that was fairly common.

Precautions are taken for relatively low risk problems like lung cancer, flipper-limbs, or infantile paralysis once the statistics add up.

Blue light damage seems likely, to me, to be in that same ballpark — decades from now people will wonder how come nobody realized there were issues to take care of to reduce the small real risks. But at this point, you need a fairly big study, and a competent statistician, to show most of the effects.

Just speculation on my part — but I do know people with macular degeneration, and I did when I was young know sailors and others who lived with bright sun and glare who did get macular damage, and even then the suspicion was that it was the blue light photons that did the damage, slowly over decades, to their retinas.

Time will tell, on this stuff. We should live so long …

But it looks to me like the LED manufacturers — at least Cree, who’s come out with a very pure amber phosphor Rebel, among others — have understood this.
The cheapjack manufacturers can make more money faster selling LEDs driven by the intense blue with a phosphor cover — we know those leak enough blue light to definitely affect biological systems, of all sorts (look up “turtle safe” lighting, for an example with charismatic megafauna that the newspapers love — or on the other end, look at how bug lights work and why we use them).;

LEDs driven by green primary emission also solve the problem — drive the right mix of phosphors and you get perfectly acceptable color rendering, and no risk.

So it goes.

Well, heck, nobody’s bothered to read all the stuff I already wrote, so I might as well do a little more.

Looking back at the original post at the top, I’m going to try to find the paper. If someone else did, I missed seeing it. Pointer welcome.

I have verified that there is, for sure, a city named Madrid, and it’s in Spain 🙂

Starting with the newspaper text, I tried
http://scholar.google.com/scholar?q=”Dr+Celia+Sanchez+Ramos”+Madrid+”Complut ense+University” — found nothing.

But — aha: “Dr” confused the Scholar search.
This finds the scientist and quite a few publications:


I’m guessing the paper written about may be:


Effects of Light-emitting Diode Radiations on Human Retinal Pigment Epithelial Cells In Vitro

Eva Chamorro1,*, Cristina Bonnin-Arias1, María Jesús Pérez-Carrasco2,
Javier Muñoz de Luna3, Daniel Vázquez3, Celia Sánchez-Ramos1,2

Photochemistry and Photobiology
Volume 89, Issue 2, pages 468–473, March/April 2013
Article first published online: 9 OCT 2012
DOI: 10.1111/j.1751-1097.2012.01237.x

That looks (to my amateur self) to be a respectable journal; part of the American Society of Photobiology, which I’ve heard of for years, serious science.
Vision researchers here comment?

Funding for the paper is cited to www.fundacionmapfre.org, which looks respectable: they publish about highway safety, home fire prevention, and much else.

One last thought, for anyone who did manage to read this much — you know that stuff about yellow filters?
It’s real. The lens of the human eye slowly yellows over time as we get older.
That explains why old ladies used to come from beauty parlors with blue-white hair (and some still do).
The optical brighteners that fluoresce in sunlight get added to white-hair cleaning and setting stuff, just like they are added to many laundry products.
And for the same reason — to brighten the blue end, which aging eyes don’t see very well.

(And vice versa — young children’s lenses haven’t yellowed at all, so they get a LOT more blue delivered to their retinas than adults — which is how macular damage may start to accumulate)
(something to remember when giving kids LED lights, or computers, or phones — they don’t see what we see. They see much more blue)

I had a cataract replaced some years back — the last year _before_ the standard replacement plastic lens began to be made with a far-blue-UV filter material.
Nowadays a cataract replacement lens transmits light about like what gets through a normal aging human lens.

But — lacking that filter — my operated eye through the clear plastic lens sees a much bluer world than I see with my normal eye’s naturally yellowed, old lens.

And — yo! I can see into the ultraviolet in the eye that has the cataract-replacement lens.
I can see a couple of spectral bands from fluorescent lights that normal people can’t see at all.

That’s a bug, not a feature.
I have to be damn careful about protecting the _operated_ eye in sunlight, as the UV is a real risk to that retina.

But I can walk around at night, using that eye, with a well filtered ultraviolet flashlight that emits almost no light that normal people can see.

It’s a stupid party trick. Or a superpower. Not sure which, yet.

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