Are modern LED lights harmful to your eyes or health?

[ssanasisredna]

I don't know, I know my eyes feel kind of sore after staring into the computer screen a couple of hours.

Work in a brighter room with higher CCT lighting ... and yes I am serious.

I have the same problem if I work in a room that is too dark, especially with lower CCT lighting.

I would also check your computer screen with your cell phone to make sure there is no low frequency PWM dimming. It's not too common anymore, but I understand they are still out there. The effects of flicker/PWM on a direct view screen are worse than when done with environmental lighting.

 

[ssanasisredna]

Kuse et al. reported that 661W cells are more sensitive to light-induced damage when exposed to light emitted by blue (464 nm) LEDs than when exposed to green (522 nm) or white LEDs (wavelength peak at 456 and 553 nm) of the same intensity (0.38 mW/cm2​). The exposure to blue light, unlike the exposure to white and green LEDs, also produced a significant increase in ROS and induced cell damage. Similar results were also observed in primary retinal cells. These data support the idea that exposure to blue light in the range of 400–470 nm (even at low levels) may damage photoreceptors and retinal pigment epithelium cells.


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I think this section makes my point nicely. You are I both know that that white LED contains a significant portion of light from the exact spectrum of a blue LED. However, they claimed that the blue LED produced a significant increase in ROS and cell damage, while the white did not. Now how much different was that damage? 10x ?? Was it a direct correlation of intensity of light in the damaging portion of the spectrum?

The other issue with these studies is they don't do enough studies at various intensities to determine if the damage level is linear or not. That is pretty critical as it could set far more effectively a "safe" level.

This brings me back to the original study you posted where 500 lux directly at the eyes was used, a value far outside "normal", and perhaps at a level that is not relevant if the level of damage at a realistic levels is not well understood (and proper CCT light was not used, and comparison sources not detailed).

... AND as we both noted, while LED bulbs at 80 CRI do have higher levels of blue, it's not as large as most people think, and LED bulbs have no very short blue, but incandescent does.

Heck, most of these studies do not even look at relative exposure to interior light and being outside for an hour or two. Maybe the people we need to worry about most are garbage collectors?

Really though, I worry most about looking at my computer screen .... one of the reasons I keep my light level high in the room as it forces pupil closure reducing exposure level (and improving focus).

 

[seery]

Are modern LED lights harmful to your eyes or health?

No, only to your wealth!

 

[JoakimFlorence]

Ha ha

 

[JoakimFlorence]

My personal opinion on the matter is that exposure over time to excessive amounts of blue light probably is at least somewhat detrimental to the health of the retina, but not as detrimental as violet light. I think the effects get exponentially worse the shorter the wavelength is.

I don't know what the exact comparisons would be, but I'd imagine it would look something like 400nm being 3 times as bad as 450nm, and 490nm only half as bad as 450nm. (And I'm sure the relationship is probably not a smooth function of the wavelength either)​

and LED bulbs have no very short blue, but incandescent does.

That's a somewhat complicated comparison to try to make. While it's true that the average wavelength of the blue light coming from an LED is a shorter wavelength than the blue light from an incandescent spectrum, it's also true that incandescent has some level of very far blue-violet light, whereas LED essentially doesn't. Nevertheless, the amount of violet light compared to the amount of blue light is not so big. (There's about a 4:1 ratio of light between 450-490nm compared to light between 400-450nm, although that ratio is going to be different with a halogen bulb at 3000K) The blue light from an LED is, for practical purposes, almost all composed of a single peak between 450-455nm.
(That's an oversimplification, but it's relevant for making this comparison here)

Then there's also that effect I mentioned. With the spectral profile from incandescent having a larger ratio of the longer wavelengths of blue light, and 480-490nm having a stronger effect on pupil constriction than 450nm (by about a factor of 2) , it may be that incandescent light results in less blue light overall from being able to enter into the retina. (if we are comparing incandescent to an LED of the same correlated color temperature)

 

[ssanasisredna]

I don't know what the exact comparisons would be, but I'd imagine it would look something like 400nm being 3 times as bad as 450nm, and 490nm only half as bad as 450nm. (And I'm sure the relationship is probably not a smooth function of the wavelength either)

Then there's also that effect I mentioned. With the spectral profile from incandescent having a larger ratio of the longer wavelengths of blue light, and 480-490nm having a stronger effect on pupil constriction than 450nm (by about a factor of 2) , it may be that incandescent light results in less blue light overall from being able to enter into the retina. (if we are comparing incandescent to an LED of the same correlated color temperature)

You have written something essentially like the second part twice now. It was not accurate the first time, nor the second.

"If you compare the spectral energy of the exact same lumen 2700"K Incan and 2700K - 80CRI bulb, from 450-520nm, they are pretty close (within 10% for typical LED). If you look at the more critical 450-500, the white 2700K bulb is up about 20-25%. Adjusted for the total ipRGC action spectrum, the LED carries a similar advantage. Of course if you use a 4000K LED, which would be much better for reading under ... you have nothing in the incan world to compare it to."

When I add in the first part of the comment, I could extrapolate that the Incan will do more damage ...

 

[HighlanderNorth]

You have written something essentially like the second part twice now. It was not accurate the first time, nor the second.

"If you compare the spectral energy of the exact same lumen 2700"K Incan and 2700K - 80CRI bulb, from 450-520nm, they are pretty close (within 10% for typical LED). If you look at the more critical 450-500, the white 2700K bulb is up about 20-25%. Adjusted for the total ipRGC action spectrum, the LED carries a similar advantage. Of course if you use a 4000K LED, which would be much better for reading under ... you have nothing in the incan world to compare it to."

When I add in the first part of the comment, I could extrapolate that the Incan will do more damage ...

So, does all the current data show that modern, indoor a/c LED's aren't any more harmful to your eyes, as long as you choose the right bulbs with an ideal color temperature? What would that ideal color temperature be, and/or which particular bulbs?

 

[JoakimFlorence]

So, does all the current data show that modern, indoor a/c LED's aren't any more harmful to your eyes, as long as you choose the right bulbs with an ideal color temperature? What would that ideal color temperature be, and/or which particular bulbs?

There's probably not a definitive cut-off.

I would imagine 4000K and less would be better than 5000K and higher, but that's not based on any particular research studies.

To make matters more complicated, it may not be entirely just dependent on the color temperature. I would imagine very high (>94) CRI LEDs might be a bit less damaging than normal LEDs (maybe by 20-30%, but that's just a complete guess) because of their slightly different shaped spectral distribution.

Anyway, it's not like LEDs are insanely more damaging to your eyes than any other light source. There's no way a 2700K LED could be more than twice as damaging as old-style incandescent lighting, if that helps put things into a little perspective. If we're talking about 3000K LED versus 3000K halogen, that difference is going to narrow even more, or it's possible they may be about the same (I don't know).

If we're talking about Metal Halide discharge lamps, it's very likely LEDs are less damaging.

Some of the early LED streetlamps that appeared were 8000K, which corresponds to 45% blue light. These caused a lot of glare.