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Comment by justin_vanw | Hacker News Reader

I'm curious why LEDs used in light bulbs could cause eye damage, but not for backlights in computer monitors or other common uses? I kindof get the impression that the blue-tinted led's are being considered 'evil' and studies are 'showing' that they are 'harmful'. Certainly these blue led's have far far far less of any wavelength at all of output than say the sun at noon...

I wouldn't be surprised to see that this study is never reproduced.

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Just a guess how this could happen with LED bulbs but not the sun: at noon, there is certainly more short-wavelength power in sunlight but if you're outside without eye protection your pupils are going to shrink down to limit retinal exposure. Out of the sun, your pupils can be open wider but the short wavelength light is still there with these LED bulbs. This is a pretty new development: humans have of course had artificial light sources since before recorded history, but flames (and much later, hot wires) had much less blue output than these specific LEDs they're testing.

Another guess: they might actually find similar retinal problems from sunlight exposure in people who spend most of their working life outdoors, but since most people in developed nations don't work in agriculture anymore their baseline population doesn't reflect a lot of sunlight exposure.

Turn the lights off in a room, and see how much of it your monitors can illuminate. Our eye's logarithmic response to light can end up confusing us about the mile-wide canyon between a glow and a light.

Sure but at the same time we are not staring directly at light bulbs for 8 hours a day.

Sure but a mile-wide canyon is a mile-wide canyon. They're just not in the same ballpark.

I think, although I'm not entirely sure, that LED backlights work in one of two ways. Either there's a white LED that is behind red, greed, and blue filters, or there are separate red, green, and blue LEDs. In the former case, the filters are likely to reduce short-wavelength light and, in the latter, case, the red and green LEDs would be inherently safe and the blue LED would most likely be selected to be longer-wavelength for efficiency reasons.

(IIRC blue and violet LEDs are close to 100% efficient, but our eyes are much more sensitive as the wavelength gets farther from violet. This means that the "efficacy" of less violet LEDs is much higher. The backlight power will be set to achieve some desired apparent brightness, so a longer-wavelength blue primary would save power.)

I wonder what OLED would be like

They didn't test computer monitors.

There's more information about the blue hazards in this report from Cree (LED manufacturer)

http://www.cree.com/~/media/Files/Cree/LED%20Components%20an...

Backlights very well might; They weren't tested in this study.

Many studies have already produced similarly disturbing findings, although I don't know if this specific study has been replicated. See my other comment.

Why are you sure monitors don't harm our eyes?

Most people don't stare directly at the Sun for hours every day like a lot of people do with cell phones.

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