Eye strain from LED backlighting in MacBook Pro

Thank you for sharing Jessiah1, really look forward to seeing a coating that could effectively fliter the harmful light so that we could look at the LEDs with comfort! Though, I think that coating should apply onto all the LED themselves instead on our spectacles!!

Speaking of filtering, I came up with a way to let me temporary use an uncomfortable screen much longer than I originally could. I found that a dark sun filtering film (those we stick onto windows for dimming the sunlight) can be very effective in cutting down the discomfort from some type of LED screens.

I cut out a small piece and now keep it in my bag all the time. So whenever I need to look at an uncomfortable LED display (e.g. when someone show me photos or ask me help them diagnosis a problem on their iPhone 5), I took out that film and place it onto the phone/display. Since that's a pretty dark film, the screen brightness will need to bring up a bit. But I would say that by using this method, the discomfort could cut down by about 80%. Enough for me to enjoy the time with my friends while looking at the troublesome display.

Note that while the effect is similar to bringing down the brightness of the display, there's a huge difference in terms of comfortability.

This method is useful for those displays with harsh bright bluish LED backlight, but probably won't help much with displays that cause trouble due to flickering.

And since those sun filtering films can be stuck onto glass, for those who desperately need to use a portable device with a troublesome display (harsh bluish LED type), they may consider sticking the sun filtering film onto those displays. I haven't tried that myself, though.

Also, many of those sun filtering films need water when sticking, so be very careful when doing that.

Further to my previous post, and regarding to those harsh bright bluish LED lights, I think the "problem" is highly related to the bluish light, but probably not entirely just about the spectrum.

Why I say that is because, on an uncomfortable screen, it's very likely that it's still uncomfortable even if it's just displaying pure green or red (but probably less uncomfortable compared to blue or white). And there should only be a minimal of blue inside the spectrum when the screen is displaying green or red.

I guess the LED is probably emitting "something" that doesn't filtered away by the screen's color filters. It also seems that "something" doesn't reduce much even if the brightness is lowered.

However, it seems those sun filtering films (which basically cuts down everything throughout the whole visible spectrum and maybe more) is able to reduce that "something" that's causing the problem.

from: http://en.wikipedia.org/wiki/Liquid-crystal_display

(...) liquid crystals cannot completely block all light from passing through. (...)

So even when screen is totally dark some light from backlight is leaking through liquid crystals. It means the LCD screen is like curtain with many small holes. By those holes light flows always in the full light spectrum of used type of backlight (CCFL or LED).

I've been following this conversation a long time. I've also posted several entries.

I would like to point out my opinion again: Sunlight has the full light spectrum. People who work outdoors near the equator do not get any symptoms from the blue sky or any other light like reflections from the sea. Also, The sun is quite intense in the Alps in the summer, and the snow reflects also the blue light that is present in the sunlight.

I've also discussed this with a couple of eye doctors, staring at a led backlight LCD is not harmful, even if it is 100% backlight level.

When I was researching, what caused my eye strain, I tried orange glasses that block the whole blue light spectrum. I tried Gunnar gaming glasses. I tried regular sun glasses. I tried the F.Lux program. None of these helped at all. When I finally read about the PWM, that was it. When I turned all of my displays to 100% backlight, the eye strain vanished and has not come back. I made sure that both of my TV's are 100% backlight, my Galaxy s3 is 100% backlight and my computers are 100% backlight, the exception being the HP ZR2740w which does not have PWM. I can have this at the lowest setting, without having any problems. Also, the higest setting, which is reall bright, does not cause any problems.

I found that it took a couple of weeks for my eyes to recuperate from the PWM flickering problem, but after that, I don't get any problems from displays where there are not PWM flickering. Be it LED or CCFL.

So I still would like to argue, that the blue light from LED is not the problem. The fact that some people report improvement from programs like F.Lux or using some blue light blocking glasses, might be placebo. Because to be really sure what causes the problems, you need weeks of testing. That's because one day you might be tired and your eyes are irritated because of that, not the blue LED. And as I said, it takes a while of not watching the PWM flicker for eyes to recuperate.

It would really help if we could try keep this as "scientific" as possible and not try to blame the problem on all kinds of "I think it's this or that" type of things.

Bottom line: Sun has the full spectrum and people working in intense sunlight do not get any symptoms. So why would a LED backlight cause a problem, especially when it is dimmed to the max (when it is not dimmed with PWM)?

I too have been following this thread for a long time. I have an eye condition called Uveitis so eye problems with LED can literally make me blind. So I have been trying to understand this problem for a while.

I am not sure if this would apply to everyone but consider this.

I first noticed that reflected light of any sort would harm my eyes, whether it be reflected sunlight or reflected indoor lighting off tiles and mirros etc. From what I understand reflected light runs in straight lines as apposed to normal light which is wavy. This is the concept behind polarised lenses. They block out certain straight lines of light. Thus reducing glare from seawater etc.

Could it be possible that the LED light mechanism is creating light similar to reflected light??

I am not sure about any of the above but it is worth noting.

I wear polarised lenses when i am outside but havent tried on an LED screen, I know that when I tilt my head on most displays the image dissapears as a result of the lenses. So I only use CCFL backlit screens without polarised glasses on and I am generally fine.

Cool guys

Later

Z

Uveitis might be a completely separate issue, I agree.

But have you tried a LED display that has been confirmed not to flicker?

All LCD displays do have a polarizer to be able to see the picture. If you remove the polarizer layer, you can see the picture only with polarized sunglasses. Both CCFL and LED.

So you could be on to something with the polarized light. Though, I'd say that the light that is emitted from LED or CCFL is already reflected light and the polarizer does the same thing as sunglasses to the light.

The CCFL does not bother your eyes probably because the PWM is lesh harsh than with LED or that the PWM is a different frequency. Some years ago I had a CCFL LCD which did not bother my eyes so much, but the PWM frequency was 130 Hz. A 180 Hz LED PWM causes severe eyestrain in 30 minutes.

Mojarvinen:

I come from a scientific background, although this area is not my expertise. I am familiar with scientific method. I submit that your desire for us not to talke about "this or that" is absolutely contrary to scientific investigation. However, it is not in keeping with being closed minded and selective. Authentic scientists gather information from various places to reach a verifiable truth, not just another idea in keeping with current trends.

Doctors who say that staring into an LED of any kind is not harmful are likely a bit pompous. How can they possibly know that. The statement is contrary to experience and logic.

The sun has a full spectrum, indeed, but we are talking about artificial light. Big difference. This statement lacks validity: people working in intense light do not get any symptoms. Returning inside from a bright day without having worn sunglasses demonstrates that the eyes experience something and have to adjust, if nothing else. That moment of blindness and blurriness could be considered a symptom and have long-term consequences if repeated.

Why LED light would cause a problem is exactly what we are all seeking to know. Clearly it causes a problem.

If you do not have the temperament for the "this and that," so be it, but do not discourage or condemn it. This is not the place for judgement. We are all bringing what we have, within reason, to support finding an answer. Pooling resources and collecting data is what we have.

Please understand that no malice exists in my response to you. The tone of your email was a bit condescending, compelling this reply.

I remember your post on the PWM flicker and was glad to be reminded of it.

Very useful and enhanced my understanding of PWM. Thank you.

Yes, sorry about the condescending tone. It's just frustrating to see that we go over an over the same suject. Few people understand what is a LED display or CCFL or and LCD.

I still would like to contest that it is not the LED light. It is the PWM flicker. And if one has not tested a PWM flicker free display, then he/she should first test it, before commenting that a program or glasses or taking vitamins helps.

That's why I want to remind every now and then, that I have completely removed the problem by using only PWM flicker free (LED) displays.

Thank you for being gracious to my comments. This post is very compelling, and I must admit that I didn't get it the previous time you mentioned. I am printing to pursue and to review lists for what others have said about PWM.

I use my computer the way most people drive their cars. I want it to operate when I turn it on and I don't want to know how it functions. I don't have the time or desire to digger deeper on electronic displays, but I must.

Frustration is a good word for this experience! It frustrates me completely that I have this sensitivity, which interferes with my work and recreational use of innovative electronic devices. I may live past my ability to use a computer or watch television!

I wish the glasses, programs and vitamins worked en masse, but I agree, success along those lines is atypical, anecdotal and probably related to placebo effect. To get an iPhone and a new computer, I'd try almost anything...anything I could understand. 🙂 Thank you for making the PWM more accessible.

Now that I understand it a bit better, I can torment the Geniuses at the Apple Store whose eyes glaze over when I mention this sensitivity.

Permit me a question about flicker. Do you think that those cheap LED Christmas lights have a high flicker rate?

Thank you again.

Here's the thing - some of us DO experience problems with artificial lights that is NOT related to PWM.

In my company's new office, they chose to use exclusively "eco-friendly" lighting, which is a combination of CCFL (with which I don't have a problem), high-intensity fluorescent (very painful), LED (also very painful) and regular fluorescent (acceptable, but still overbright) lights.

In the areas with high-intensity fluorescents, my eyes IMMEDIATELY become tired, and if I attempt to READ anything - books, magazines, the screen of my laptop which has never given me problems in the years I've used it - I experience eyestrain and headache within a few minutes.

In the areas with CCFL, my eyes are ok if I use a good source. We have a workroom where we build servers and network stacks, and I can be in that room for quite a while without problem. The only issue in there is TOO MUCH light, as they put CCFL cans every couple feet, 9 lights in a room that is only 15x15 which is maybe 4 lights too many.

In the areas with regular fluorescent, my eyes are ok but again it's TOO BRIGHT. They put mirrors, reflectors, and doubled-up light fixtures everywhere. Instead of the normal distribution of light, there's maybe 50% too many fixtures so my eyes quickly get tired.

And in the areas with LED, I literally cannot focus. This is not made up - MANY people have noticed this. The new LED streetsigns that businesses put up to advertise their wares have actually been the subject of lawsuits due to the fact that people are blinded by them, and there are rampant problems in places that have switched to them exclusively.

I suspect that this problem will only get worse - right now it's a very small minority of people affected, but as these lights become more common it will be a much larger percentage and organizations will be forced to act.

For me, a combination of the following has worked out "ok", but not perfectly:

1. I only go to the office every other day most weeks. This week I have to go in 3 days in a row and it's really wearing on my eyes. I'm very lucky that my employer is ok with a 3-day in-office schedule per week, and that I was able to arrange Monday/Wednesday/Friday. The days at home really give my eyes a break most weeks.

2. I have removed the high-intensity fluorescent over my desk and use natural light from the side through a translucent shade as my primary light source. This is imperfect, since 6 feet behind me and 6 feet to the right of me are MORE high-intensity fluorescents, but if I wear a visor the glare from those ones are minimized.

3. I wear Gunnar-tinted glasses over my contacts when I have to be at my desk for long periods. This further cuts the glare. When I walk around the office from light source to light source, the gunnars really help as well. I am currently custom-ordering some gunnar-tinted "computer glasses" optimized for my screen distance (2-4 feet) and tinted with Gunnar (and Crizal Sapphire if I can double up!)

But I still suffer. 9 months ago this wasn't even remotely a problem as I worked under old-style "white" fluorescents.

Is PWM a problem? Absolutely. Even under the best lighting, screens with intense PWM are a problem. But the laptop I am using right now causes me no eyestrain, and it has PWM and LED backlighting.

There is SOMETHING about new LED's - whether it's their light spectrum, their transmission matrix, or SOMETHING - that makes this problem much MUCH worse for most of us.

I'm glad eliminating PWM fixed your problem - it's the easiest thing in here to control! A new monitor solves it! Our other problems are much harder.

One thing I was wondering. Am I correct in saying that the dimming effect from using pulse wave modulation is that the 'perceived' brightness is reduced. The big question in my mind is, does everyone perceive the brightness the same?

David,

Yes, and no in that order. The overall effect is a dimmer screen, but not everyone perceives it the same. 99% of the population just sees a dimmer screen. 1% can see flicker, and maybe 10% of that 1% is in this thread and sees it as pain or strobing.

Everyone has a different sensitivity level.

PWN on a CCFL is less harsh because the light "fades" instead of being instantly off. Kind of like instead of a strobe light you take a flashlight and wave a translucent piece of plastic in front of it. The light never goes OUT, but gets dimmer and brighter. Much less painful.

Some people in this thread claim that the MBP and the latest iphone & ipad dont use PWM. Personally even if i keep the iphone at full brightness, while i feel it is better than having the backlight lower than full, i still get a strange headache. I have tested the iphone and MBP at full brightness even after a long time of adequate rest.

What i can say is that if at full brightness, personally, my eyes recover much faster, but still it makes me think twice to use the phone or laptop. This for me makes the devices unusable. With the older apple laptops (ccfl backlight) i could work without the slightest discomfort for many hours.

I have also tested the same way Lumia 920 and SG3 and i get the same discomfort (i.e. at full brightness and after adequate rest).

Do you also imply that if used at full brightness the eyes in due time get accustomed to the display since there is no flicker?

Gurm24,

I can appriciate that you have problems with office LED lights and other lights. You say that your laptop with LED and PWM does not cause problems. This is exaclyt to my point about that we should be as scientific as possible. You should measure the PWM flicker frequency with a camera or oscilloscope and if possible, find out what kind of LED's the display has. If the PWM frequency is the same as with other PWM's that cause problems to you and if the LED light spectrum and intensity is aboutu the same as other LEDs, then it's a strange thing and we should continue to research this, to find another reason why some displays cause eye strain. But you complain about too bright lights, mirrors etc. I'd say that it's quite atypical. Now, this whole problem with PWM is atypical, but the point here is sensitivity to LCD displays, not general atypical sensitivity to bringht lights and office LED lights.

I mean, there are all kinds of problems that people have with their eyes, but those might not be related to the same issue that this discussion is about. As I've understood, many are like me, no other problems with the eyes, except the sensitivity to LCD PWM flicker.

If we want to draw manufacturer attention to this, we can't have people with all kinds of eye problems reporting sensitivity to LCD's, though as problematic their cases might be.

David,

I don't see any flicker, not above about 80Hz. So I do percieve the PWM dimming as dimmer and do not see any flicker, but my optic nerve does register the flicker, which is probably the reason it makes my eyes red and ichy.

I don't think that Christmas lights flicker, as I think they would need to have the PWM for that, but I'm not sure. No data on that.