Do LED lights cause permanent eye damage?

July 2, 2014 1:49 PM

I came across this article and became concerned about my eye health, in light of a new LED monitor that I recently bought and use for about four hours each day at home (at work, I look at an older LCD monitor with a CCFL backlight for eight hours). Is this something to be concerned about? Also, can some sort of (UV) filter be placed in front of the screen to reduce risks? Currently, I have my LED monitor set to 0% brightness and 25% contrast.
posted by kalsifur to Health & Fitness (6 answers total)

I found the paper in question here. I don't have time to read it now, but maybe someone else can take a look at it.

I will say this: I'd be hesitant to make any lifestyle decisions based on the results of a single in vitro cell culture study.
posted by mr_roboto at 2:05 PM on July 2, 2014 [3 favorites]

For what it's worth, this occurred to me when I started working in front of two 21" LED monitors. I never followed up on it because I wear glasses, and normal, untreated plastic lenses block a lot of UV on their own, and I've heard polycarbonate lenses are even better. On top of that, I always pony up $15 or whatever for the extra UV-absorbing dye treatment.

So, if you wear eyeglasses, I would guess that you really have nothing to worry about.
posted by pullayup at 2:13 PM on July 2, 2014

I wouldn't worry about it. The paper in question took cells in a petri dish and shot lasers at them, basically. The test was the equivalent of staring directly at a 100w lightbulb for 12 hours. Not something you'd be likely to encounter with an LCD monitor, and you'd stop before it got that painful.

Plus, this quote from the researcher - ""Eyes are not designed to look directly at light — they are designed to see with light" makes no sense at all. Light reflected is the same as light emitted, except, possibly in intensity.

If you do the usual stuff - look away once in a while, don't strain your eyes, etc etc. Then, there is little risk of long term harm.
posted by Pogo_Fuzzybutt at 2:18 PM on July 2, 2014 [11 favorites]

Also, this:

Eyes are not designed to look directly at light — they are designed to see with light," Sánchez-Ramos said.

Is an almost nonsensical statement. You see stuff because light enters your eyes. It's possible that it is a bad translation or an incredibly poor way of stating that there is a meaningful difference in the amount of UV light that your eyes receive by looking at something reflecting sunlight vs. the amount of UV light emitted into your eyes by an LED of equivalent brightness, but I doubt it. Sunlight contains hell of UV (enough to damage the DNA in your skin cells so bad in about an hour of exposure that it triggers cell death via a self-destruct mechanism, a.k.a. gives you a sunburn), and it's freaking everywhere for most of the day.

p.s. Wear sunscreen and sunglasses that provide UV protection when you're outside, and make sure you wear appropriate eye protection if you ever use an arc welder.
posted by pullayup at 2:24 PM on July 2, 2014 [5 favorites]

You can certainly say that perceptually white light emitted by an LED contains proportionally more blue light than perceptually equivalent light emitted by a fluorescent or incandescent bulb, or white light from the sun, without being wrong, but it would be more helpful to say that white light from an LED contains *proportionally less* violet, green, red, and infra-red light than sunlight does.

A white LED is actually a blue LED with a phosphor coating which absorbs some of the blue light and re-radiates it as yellow-orange light. This mix is calibrated to stimulate all three of the color receptors in our eyes in the same ratio that they would be stimulated by white light, so even though the light coming out of the LED doesn't actually fill the same spectrum as sunlight or incandescent light, it still looks white. ("Warm white" means it has more phosphor, "cool white" means it has less, adjusting the balance of blue to yellow-orange light.)

The phosphor cannot add energy to the photons it re-radiates, so it can only drop that blue light down to longer frequencies. A typical "InGaN" blue diode produces light in a very narrow spike centered on 450nm. There is effectively nothing at 400nm, and the low end of "ultraviolet" is generally considered to start at 380nm.

With only a very small degree of approximation, then, we can safely say that "LEDs do not produce any ultraviolet light".

So what about the blue light? Photons at blue frequencies certainly carry more energy than photons at yellow or red frequencies, so could the "extra" blue photons emitted by LEDs be causing more damage?

Well.... maybe. That's an interesting question. But like I said above, it's not really the case that white LEDs are producing more blue photons than other lights of equivalent brightness: it's more like they are producing less green, orange, red, and infrared for the same amount of overall illumination.

You can see what's going on with the light, you know? If it's too bright, it's too bright, and you turn it down, because it feels too bright. If there's too much blue for the amount of yellow-orange, then it feels like "cold" light, and if you're like most people you say "yuck" and buy different bulbs with more phosphor on their diodes.

This article is nonsense, and it's possible that the research it describes is also nonsense. Either way, you have nothing to fear from LED light.
posted by Mars Saxman at 5:07 PM on July 2, 2014 [3 favorites]

With just a single study, I don't think I'd be too concerned. More information is needed. However, I think keeping the brightness and contrast low, as you're doing, is a good preventative.

"Eyes are not designed to look directly at light — they are designed to see with light"

I believe this statement refers to looking into the direct, unfiltered source of a light itself (ie: the sun, the bulb, ect.).
posted by stubbehtail at 5:15 PM on July 2, 2014