LEDs and Eye Safety

Luxeon Publication AN16, "Custom Luxeon Design Guide", has the following warning:

LEDs and Eye Safety:
In the 1993 edition of IEC-60825-1, LEDs were included: "Throughout this part 1 light emitting iodes (LED) are included whenever the word "laser" is used." The CENELEC document EN 60825-1 contains all the technical content of the IEC standard. The scope of the IEC standard states that "…products which are sold to other manufacturers for use as components of any system for subsequent sale are not subject to IEC 60825-1, since the final product will itself be subject to this standard." Therefore, it is important to determine the Laser Safety Class of the final product. However, it is important that employees working with LEDs are trained to use them safely.

Most of the products containing LEDs will fall in either Class 1 or Class 2.

A Class 1 label is optional:
CLASS 1 LED PRODUCT

If a label is not used, this description must be included in the information for the user.

Class 2 products shall have affixed a laser warning label, and an explanatory label:
LED RADIATION
DO NOT STARE INTO BEAM
CLASS 2 LASER PRODUCT

Amendment 2 to IEC 60825-1 is expected to be published in January 2001. The CENELEC equivalent is expected to follow three months after the IEC publication. This document contains increased Class 1 and Class 2 limits, as well as the introduction of less restrictive Class 1M and Class 2M.
For the exact classification and further information, the IEC documents can be used:
IEC-60825-1

This also is discussed in 21CFR 1040.10.

Does anyone have any idea of what the implications of this all is?
Has anyone characterized an LED illuminating device under these standard?

I'm a bit bewildered.

Actually, I've wondered about the safety of staring directly into the light of a white LED. My 2 year old likes to play with my flashlights (apparently it's genetic) , but I don't like him looking directly into the beam because I'm concerned it might damage his eyes. Do I need to worry about this?

Maybe telephony will have something to say... But those warnings were for luxeon star LEDs which are much brighter than the LEDs most of us have in our flashlights and keychain lights. Also the color matters I suppose.

I suppose with the nichia white LEDs it might be damaging if you mercilessly kept staring at the beam of your led at close range (an inch or two) and refeused to stop looking even when your eye started to hurt. Id be surprised if any adult was able to permanently damage their eye from occasionaly flicking it at their eye - but who knows. As far as kids go I wouldnt let one use a bright flashlight unsupervised.

I'm not aware of any documented case of eye injury caused by momentary viewing of an LED.

There is a potential for damage; most of this will be from LEDs radiating in the 400s to low 500s of nanometers - violet, blue, blue-green, and green; but it would generally take a sustained blast and intentionally defeating the eye's aversion reflex before any damage would occur.

The act of flashing any visible small-junction LED of any color into the eye (from point blank range) on a momentary basis (less than 200 milliseconds) will *not* cause any injury. The source is too large and cannot be focused to a pinpoint on the retina like a laser can.
Large junction devices like the Luxeon should also not cause damage this way, but the much higher optical power might cause other types of damage I haven't yet read up on. So just don't do it with a Luxeon.

Shorter wavelengths have a different danger though, and that is from a photochemical reaction between the higher energy photons and the proteins that make up the transparent parts of the eye. UV and near-UV LEDs shouldn't be stared into at all, even if you're a risk-taker and stare into other kinds of LEDs. A brief flash is alright, as is extended exposure from a distance of a couple of feet or more. But it's a no-no to put one of these directly up to your eyeball and push the button. The damage mechanism is a photochemical reaction that could cause clouding or cataracts in the eye's lens. And because the eye's sensitivity to radiation just outside the visible spectrum is so low, the iris is usually wide open and the lens is irradiated much more strongly than it would be with a yellow or green LED of the same optical output power (milliwatts).

The best advice is don't.
At least not from point-blank range.
As for kids playing with white LED flashlights, if you're concerned that he's doing more than just occasionally flashing himself with it, resistor it down (to reduce its intensity) and give it to him as his own, then go buy another one for yourself.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> As for kids playing with white LED flashlights, if you're concerned that he's doing more than just occasionally flashing himself with it, resistor it down (to reduce its intensity) and give it to him as his own, then go buy another one for yourself.
<HR></BLOCKQUOTE>

All right! An excuse to buy another flashlight!!!

I'd imagine there would be little risk of eye damage from the LEDs currently sold.

A recent study has found typical laser pointers harmless:

Laser Pointers and the Human Eye: A Clinicopathologic Study

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by The LED Museum:
The best advice is don't.
At least not from point-blank range.
As for kids playing with white LED flashlights, if you're concerned that he's doing more than just occasionally flashing himself with it, resistor it down (to reduce its intensity) and give it to him as his own, then go buy another one for yourself.<HR></BLOCKQUOTE>
I suppose one could also frost the LED using that method w/ Ajax or Comet and the Pink Pearl eraser (suggested by that, uh, that one guy whose name I can't remember). The more diffuse beam would probably be less damaging to a kid's eyes.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by AtomicCow:
I'd imagine there would be little risk of eye damage from the LEDs currently sold.
<HR></BLOCKQUOTE>

One other item to keep in mind is that an LED that is really overdriven can possibly achieve output of 20 to 40 milliwatts, or up to nearly ten times that of a common laser pointer near the top of its Class IIIA range.
Violet and blue LEDs would be more likely to be in this higher power range; followed by white, blue-green, green and some of the reds. Yellow-green and yellow LEDs usually turn to a burnt orange color when you overpower them to this degree, so this isn't done as often with them as it is with some of the other colors.

Wider viewing angles are also inherently safer, as it's much more difficult to get all of their light through an already constricted iris.

I think the only ones I'd keep out of the kid's hands are the violet, UV, and infrared. The damage mechanism for short wave visible and UVA is understood less, but the potential for biochemical/photochemical damage exists where it does not with other visible LEDs. Infrared LEDs shouldn't be stared into by anybody, at least not those emitting more than a few milliwatts.

I remember asking an opthamologist about laser pointers damaging the eye - he said the only way to damage your eye with a laser pointer is if you poke yourself in the eye with it!

Craig's advice is best - don't look at the UV and IR leds, and don't stare at any of them up close. Simple and sensible.

The chances of any of the visible LEDs actually damaging the eye approaches 0. You'll do more damage looking at a lit p61 module up close (and you'll get a nice suntan to boot!).

Luxeon Stars kick major butt, iyogii. They're a very good product.

I put a topic with a lot of references into the Cafe' section a while back.

Short answer -- macular degeneration is the big risk; it happens due to cumulative blue and UV range light, over a lifetime. The way the lens of the eye yellows after the first few years of life offers some protection (and people like me with old style cataract replacement plastic lenses lose that protection and can see into the ultraviolet range -- I can use a UV Arc-AAA as a flashlight if I look at the scenery underfoot using it with my left (cataract implant lens) eye, but can barely see its light with my normal 50-ish natural lens. And I've read that the UV lines in spectroscopes from mercury vapor lights (including office fluorescents) are visible through these lenses.

Short answer again -- blue is dangerous because it's cumulative over time. And it can be a short time -- there are a couple of documented cases where opthalmological slit lamps of the older blue style were left shining into a patient's eye when the examiner got distracted and the person lost sight in that eye. Newer slit lamps have blue blocking filters.

Now, about those d*mn*ble electric blue headlights, I dunno.

The LED Club pendant I gave my youngest is flatened on the end with a file, so it no longer produced a beam instead giving off diffused light, he is still happy with it.

These Luxeon stars might damage the eye is you stare into them, but my thought is this:-

Will there be any adverse effect from long term use of white LED's in a torch for reading a couple of hours a night ?

In an under-developed country without electricity, a solar powered white LED torch could be the only option.

There is some grim reading, which I can`t put my finger on the reference to, at mo, regarding testing of LEDs on monkeys.

The conclusion was much as Craig has said, UV, blue,true green and IR are not for staring into. Blue LEDs IIRC had a particulary bad effect in a suprisingly short exposure time.

Think it also has to do with power density from a point source, but the maths and phsyiology will leave to someone better qualified.

No one wants the hysteria that surrounds laser pointers and where possible would like to avoid having to put Laser warning and class labels on LED products particularly consumer LED products...

However education to end users not to stare into the pretty blue lights would be a good thing.

Adam

I've noticed that the newer high power Crees come with warnings, at least on eBay. I suspect this will all turn out a bit like the laser thingeys, which were initially deemed to be as harmless as mother's milk, but later on we all wised up. See
http://en.wikipedia.org/wiki/Laser_safety