Q: Eye strain from LED backlighting in MacBook Pro

PWM could certainly be a problem, but let's get back to what's already been established far back in this thread: new MacBooks don't use PWM, and they still cause eye strain for a lot of people.

So far my experience is this

- MacBook Retina 15" mid-2012: severe eye strain, headache, nausea

- MacBook 15" mid-2011: no problems at all

- MacBook 15" mid-2011 with Bootcamp Windows 8: eye strain, head ache

- Samsung 15" Chronos 7 2013 (Win 8): very minor eye strain that seems to wear off

None of these use PWM.

So far I've seen two theories that I find somewhat credible but still very much unverified:

1) Strong blue light that my eyes cannot handle well

2) Some kind of pixel level flicker technology for creating color tones. I forget what it's called. But it corresponds to what I'm seeing when I look closely on the screen - the pixels that are supposed to display a static color, let's say green, are in fact randomly flickering between darker and lighter shades of green. Looks like someone is applying a very faded random noise filter 50 times / second.

Edit:

I would also like to point out that not everyone has the same problem or any problem at all. I'm pretty sure I belong to a small minority with this problem. If we don't acknowledge this and present it like LEDs are the end of civilization, we lose credibility to the anyone in the majority who are absolutely fine with any of these screens.

Hello everyone, it has been quite a while since my last post. During the past many months, I have been searching for ways trying to reduce my eyes stress while working with computers at work.

My eyes used to stressed out within a very short time in office. But I think I have now found a combination of ways that work for me, and I can feel that my eyes are still able to focus clear and sharp even when I leave office in the evening.

I'm detailing below four items that I think have most impact to my eye stress. Hope what I experimented could help some of you.

1. Environmental lighting
   It may sound obvious, but if your eyes feel irritated sitting in office even just reading a normal book, you're kind of screwed... I think the first benchmark is that the lights should let you read a normal book comfortably.
   
   I fortunately am allowed to change the lights around my office desk, I have tried many different kind of lights (different brands of fluorescent lights / ballast / halogen lights / incandescent lights / LED lights (!!), etc.). To my surprise, a cheap unbranded T8 fluorescent tube on traditional magnetic ballast works best overall for my case.
   Normally, I would believe indirect incandescent to work best most of the time, but for my case, I guess it also relates to how well that can be physically installed around my desk and how well it blends with other lights in my office (which are all fluorescent).
   Generally speaking, try experimenting with different lights until you find the most comfortable one.
   
   I think it's also important to note that the light shouldn't be too bright and has to be evenly lit around the working desk. So, while the incandescent lights are comfortable in general, it probably won't do good if you put only one bright incandescent to lit up your working area. The eyes would tire out eventually if there's a high contrast of light.
   
   
2. Glare
   Despite some people has reported improvements when using anti-glare displays, I really don't think the anti-glare coating is a solution to most of the "sufferers" in this forum. Lots of discussion on this already, so I'm not going to eloborate.
   
   Having said that, I think the glare issue needs to be delt with. Generally speaking, we should place our monitor so that we don't see any glare (bright spots) even if we uses a glossy disply. And we should see no bright lights behind the screen too (it's not a bad idea to place the monitor in front of a wall).
   
   If necessary, install blinds on windows and / or re-orientate the desk.
   
   Also, try to avoid placing the monitor right below any direct light, whether that's incandescent nor fluorescent. It seems that our eyes tend to use more effort during those situations. The situation seems especially worse if the monitor is a LED. A CCFL monitor appears to have relatively less adverse effect in that light setting.
   
   
3. Spectacles
   I have no problem focusing close, and don't require a reading glass normally. But since I was desperate in trying every way to help my bad eye strain, I went ahead and prescribe a pair of spectacles specifically for computer use.
   
   It is a slightly less power (-0.5) spectacle than my usual one, and I found it to be surprisingly helpful!
   In fact, I am now recommending all my friends who have eye tiredness issue to give that a try. I think a less power spectacle helps the eye muscles relax, even for those people who have no problem with their monitors.
   
   
4. Monitor
   Finally, the monitors (!!!). I have tried many different monitors! To cut things short, it doesn't seem to me that all LEDs are troublesome. Earlier generations of LEDs appear to be much more comfortable than current ones. For example, I think my first generation of LED iMac at home and my old iPad 2 are very comfortable. However, it's now harder and harder to find any new LED displays that's not uncomfortable...
   
   Anyhow, after trying and trying, I think my eyes like the old CCFL aluminum Apple Cinema Display most. The one I'm now using is a 24 inch model, I bought it used online.

The "methods" that I discussed above are not something ground breaking, but I think they all helped little by little together.

Instead of almost feeling handicapped, I can now work normally. And I think that's a very big difference, at least to me!

Good information, I think something important for everyone in this discussion to acknowledge is how we do not completely understand exactly what each of us is experiencing and what may work for some people may not have a positive effect for others. The reason I say this is after reading about this for almost a year now the common theme is that there are varying degrees of sensitivity. I myself have only established 3-4 other individuals through direct conversation who have the exact degree and sensitivity issue I myself have ( I do believe there are many more discussing the issue in this forum I have not spoken with yet who are probably experiencing the same level of sensitivity).

I will say that Fluorescent lights do give me eyestrain accompanied by terrible headaches however LED lights make me VERY VERY sick, Vertigo, severe migraine, poor motor function and general brain dysfunction. I have a friend in IT who is complaining about eyestrain from his new LED monitors and he believes he is more tired and getting headaches more often, to be clear this is not the same thing I am experiencing and many others who are here discussing this issue. I cannot look at any LED monitor at all without immediately being affected, after 5 minutes I am completely looped out! I am currently on disability because of overhead LED lighting, this is what everyone here should be very concerned about, when overhead LED lights are everywhere your monitors will be the least of your problems.

So my message is not to say that we should stop trying to cope but to please be aware there are some of us who are so sensitive there are no methods we have found so far that dull the effects for us.

I have stated this already but I will be more detailed: Crizal anti-glare "Sapphire" coating on my plain power glasses works for CCFL back lighting and stores like Walmart who have intense fluorescent overhead lighting however this does not work at all for LED. These glasses block a small % of a wide spectrum of blue light. There is a new anti-glare coating in pilot phase that may be the complete answer for those like Eric above who gets some relief from changing his environment and can view LED screens for some period of time, I have tried it and it will not completely solve my problem but maybe there is more to come with this type of product. This new coating blocks %20 of a specific spectrum of harmful blue light LED lights are strong in, I may be involved in a trial for something more aggressive sometime in the near future. This is the only thing that has had any positive affect for me in regards to LED lighting in over a year of trying all sorts of methods. When I wear them I still feel affected by the lights initially however I get about 10-15 minutes before my symptoms really start kicking in compared to seconds without the glasses, this is a huge difference considering how sensitive I am. 

The new coating that you mentioned sounds really interesting!

Just curious, would this be the coating that you're testing?

http://www.axonoptics.com/next-gen-light-sensitivity-glasses/update-on-next-gene ration-lenses/

That would not be it however if you look at that image of the lenses you can see how they have an interesting purple, orange maybe yellow? Hue coating. Something I would share is that if the reflective coating appears purple/blue or green it is probably blocking certain wavelengths/spectrums of those colors. This is the same concept as the lenses I am trialing right now http://www.crizalusa.com/Crizal-Lenses/Crizal-Prevencia/Pages/default.aspx

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.