RMartin111

Q: Eye strain from LED backlighting in MacBook Pro

There is one relatively serious con of the new LED backlit displays in the new MacBook Pros that seems to not get too much mention in the media. About a month ago I bought a new MacBook Pro to replace my standard white MacBook. One feature of the MacBook Pro that I was unaware of was the introduction of the LED backlit display to replace the CCFL backlight.

Once I started using my new laptop for long periods of time, I noticed severe eye strain and minor symptoms almost similar to motion sickness. After 20 or 30 minutes of use, I felt like I had been looking at the screen all day. Much longer and I would get headaches. If I used the old white MacBook (with its CCFL display), I had no eye troubles at all. Moreover, I could detect a distinct flicker on the MacBook Pro display when I moved my eyes across it - especially over high contract areas of the screen. White text on a black background was virtually impossible for me to read without feeling sick to my stomach because of all the flickering from moving my eyes over the text.

The strangest thing about all of this was that nobody else I showed the screen to could see these flickers I was seeing. I began to question my sanity until I did a little research. Discovering that the MacBook Pro introduced a new LED backlit display started to shed some light (so to speak) on what might be going on. I had long known that I could see LED flicker in things like car taillights and christmas lights that most of my friends could not see. I also knew that I could easily see the "rainbow effect" in DLP televisions that many other people don't see.

My research into LED technology turned up the fact that it is a bit of a technological challenge to dim an LED. Varying the voltage generally doesn't work as they are essentially designed to be either on or off with a fixed brightness. To work around this limitation, designers use a technique called pulse width modulation to mimic the appearance of lower intensity light coming out of the LED. I don't claim to fully understand the concept, but it essentially seems to involve very briefly turning off the LED several times over a given time span. The dimmer the LED needs to appear, the more time it spends in the off state.

Because this all happens so very quickly, the human brain does not interpret the flickers as flickers, rather as simply dimmer light. For most people that is. Some people (myself included) are much more sensitive to these flickers. From what I can tell, the concept is called the "flicker fusion threshold" and is the frequency at which sometime that is actually flickering is interpreted by the human brain as being continuously lit. While the vast majority of people have a threshold that doesn't allow them to see the flicker in dimmed LEDs, some people have a higher threshold that causes them to see the flickering in things like LED car tail lights and, unfortunately, LED backlit displays - leading to this terrible eye strain.

The solution? I now keep my screen turned up to full brightness to eliminate the need for the flicker-inducing pulse width modulation. The screen is very bright, but there are no more flickers and I love my MacBook Pro too much to exchange it for a plain MacBook with CCFL backlighting (which will also supposedly be switching to LED backlighting in 2009 anyway.) The staff at my local Apple store was of course more than helpful and was willing to let me exchange my glossy screen for matte even though I was beyond the 14 day return period. I knew that wasn't the problem though as my old MacBook was a glossy display. I've decided to stick with my full brightness solution. Sitting in a brightly-lit room tends to help alleviate how blinding the full brightness of the screen can be. In a dimly-lit room I guess I just wear sunglasses. Either way, the extreme brightness is worlds better than the sickening flicker I saw with a lower brightness setting

I would caution anybody considering buying a product with an LED backlit display to pay careful attention to make sure you don't have this same sensitivity. Turn the screen brightness down, find a high contract area of the screen, and quickly move your eyes back and forth over the screen. If you can detect the flicker, you may end up with this same problem.

I have no idea what percentage of the population has this sensitivity. I imagine we will hear more about it as more and more displays start using this technology. Hopefully the Apple engineers will come up with a way to eliminate this flicker some of us can see.

Russ Martin

15-inch MacBook Pro, Mac OS X (10.5.4)

Posted on Aug 23, 2008 8:25 AM

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Q: Eye strain from LED backlighting in MacBook Pro

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  • by mvanier,

    mvanier mvanier Mar 7, 2014 12:47 PM in response to Jessiah1
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    Mar 7, 2014 12:47 PM in response to Jessiah1

    I haven't posted for a while, but I have some new information that might be interesting to some of you.  I got a Dell U2413 monitor because it was measured to be PWM-free for all brightnesses above 20, and even below that the PWM frequency is so high that I doubt anyone could detect it (over 8000 Hz).  It also has the GBr LEDs (green + blue with red from a phosphor) which sounded interesting and which supposedly gives better color than normal white LEDs (blue + yellow from a phosphor).  I'm using it with a new Macbook dual-booted with Mac OS X and Ubuntu so I can control for temporal/spatiotemporal dithering (Mac OS X uses it, Ubuntu doesn't (at least on Intel GPUs)).  This has been a very interesting experience.  The first things I noticed were that the color really is much better than typical white LED backlights, very rich and vibrant.  Also, the flicker, if there is any, is not annoying and is certainly no worse than what I've experienced with CCFL-backlit monitors.  That left me with two potential problems: dithering and blue light (color spectrum).  When I got the monitor my eyes and brain had already mostly adjusted to the dithering to the point where it really wasn't bothering me much, but I was still getting eyestrain, which I assumed was from the blue light spike.  Using F.lux (Mac OS) or Redshift (Linux) made a big positive difference, which confirmed it.  What I've discovered is that the different eyestrain triggers cause very distinctly different kinds of eyestrain.  Eyestrain from PWM or dithering is experienced as aching eye muscles, because the flickering makes the eye move around a bit trying to follow the flicker.  In contrast, eyestrain from blue light spikes is experienced as a sore, burning sensation in the eyes.  But here is the really good news: over a period of weeks, the eyestrain has simply faded away!  My eyes have adjusted to the new monitor.  It's not complete; I still need to use F.lux/redshift for comfort, and at pretty strong levels (F.lux at about 3700K is the most comfortable currently).  But I don't have any problems using the monitor anymore, which is great.

     

    I think the lesson is this: the eyes and brain are very adaptable, and can compensate for a lot of variation in light sources.  When people get cataract surgery, the new artificial lens that is implanted is completely clear whereas the original lens was generally very yellowed.  The patients initially see everything as way too blue, but over a period of about three months their eyes adjust and things look normal again.  I think this is what is happening here.  The light from CRT monitors didn't bother me because I'd been watching CRT televisions my whole life.  Fluorescent lights were the same story.  In contrast, white LEDs have a light spectrum my eyes had never seen before, and I obviously needed time to adjust to that.  I recommend that people with this problem start using the monitor for no more than an hour a day until they adjust, then increase the time gradually.  It seems that the dithering problem can be compensated for even faster than the light spectrum problem, since after only a couple of weeks that didn't bother me either.  I don't know about PWM; it's possible that PWM is such a gross effect that some people can't learn to ignore it, but since there are lots of PWM-free monitors out now, why not just get one of those?

     

    The only other thing I did is to start taking cod liver oil supplements (in moderate doses; large doses can be harmful!).  This was just to make sure that my vitamin A levels were good, since vitamin A is a precursor to retinal, the primary visual pigment.  I have no idea if this helped, but it didn't hurt.

  • by Jessiah1,

    Jessiah1 Jessiah1 Mar 7, 2014 2:24 PM in response to mvanier
    Level 1 (0 points)
    Mar 7, 2014 2:24 PM in response to mvanier

    Mvanier, I also take fish oil supplements twice a day (For about 2 months now), there is research that points to fish oil helping keep dry eyes from going dry. This would definitely help those with that issue if it was part of their problem, no real help for me there however fish oil also helps with inflammation so there is a possibility it helps with headaches through swelling reduction in the brain? It is a tricky supplement and people should speak with their Dr. before using to get accurate amount and type recommendations, some are not processed well so a little research goes a long way when considering supps. Your Dr. may feel a higher than recommended does is needed for results as well.

     

    Also, it sounds like the monitor is using similar tech. to the Sony triluminos display and could be reducing the amount of blue light emitted, would be really helpful if someone had a good spectrometer to measure this with all the different devices and post the results.

     

    Does anyone know if there is a cell phone in the USA with a triluminos display?

     

    Jesse

  • by crazypicard,

    crazypicard crazypicard Mar 8, 2014 12:59 PM in response to RMartin111
    Level 1 (0 points)
    Mar 8, 2014 12:59 PM in response to RMartin111

    I was eating 2 cans of sardines everyday for awhile. That equaled 3 grams of Omega 3 a day. It's supposed to help with dry eyes. I didn't really notice much of a difference. The two biggest things that have helped me Is vitamin B2. It's helped with reducing the migraines. Bilberry I think was the greatest Improvement so far. Although all of these things only help a little.

  • by tfouto,

    tfouto tfouto Mar 10, 2014 3:18 AM in response to Jessiah1
    Level 1 (0 points)
    Mar 10, 2014 3:18 AM in response to Jessiah1

    Jesse, Sony Xperia Z2 has this tech. Is not yet available, but should be really soon. This month or maybe early April.

     

    mvanier: thanks for the sharing.

    I believe it's possible for the eyes to adapt, to a certain extend. If the monitor is too agressive in blue light, simply it's not possible...

  • by peter_watt,

    peter_watt peter_watt Mar 10, 2014 3:34 AM in response to tfouto
    Level 3 (910 points)
    Mar 10, 2014 3:34 AM in response to tfouto

    Blue light and UV can be completely blocked with suitable yellow lenses such as ski glasses, if that is the cause. 

  • by luisx,

    luisx luisx Mar 10, 2014 4:14 AM in response to tfouto
    Level 1 (0 points)
    Mar 10, 2014 4:14 AM in response to tfouto

    I had my beloved iphone 4 for nearly 4 years and has been like an oasis in this terrible times where I couldn't look into any new led screen. I've had 7 laptops bought and returned over the last 3 years and a handfull of monitor with the same luck... (and 3 televisions too)

     

    So, last friday I upgraded my phone to IOS7 and since then I can not look at it for even a minute! Go and explain that. Obviously the screen was good as I could use it for many hours during 3 years. Great phone with ios 5. There is for sure a software and driver issue to blame in here. Idiot of me, late I found many forums with users reporting the same and advising not to upgrade. Now here I am with an unusable phone. To my surprise it is technically impossible to downgrade again, even with jai.b.eak options. I am so disappointed, this is unaceptable. Now apple I hat.e you! Why did you do that to me??? Certainly it is over between you and me, never again a product from you. Enough

     

    I am looking forward to hear from anyone that can mention a tolerable phone. Does the experia trilumious work well?? Will the z2 be worth waiting? Any other brand recommended?

     

    Thanks for listening to my frustration,

     

    Luis

  • by tfouto,

    tfouto tfouto Mar 10, 2014 4:26 AM in response to luisx
    Level 1 (0 points)
    Mar 10, 2014 4:26 AM in response to luisx

    Luis,

     

    I guess old phones would be better. I will wait for the Z2, to see if it will be ok. That's what i hope, but i dont know.

    Xperia Z1, i think already is triluminos but technology is not advanced.

     

    So i guess wait for Z2, or go to an old phone. Maybe Android who dont have updates, or you can choose not to update.

     

    Can you lower the brightness and contrast on ios7 and see if it helps a little?

  • by spprt,

    spprt spprt Mar 10, 2014 4:32 AM in response to luisx
    Level 1 (0 points)
    Mar 10, 2014 4:32 AM in response to luisx

    I have the same problem. iOS 7 basically destroyed my iPad 4, which I cannot use anymore. I don't know what to do.

  • by LovesDogs0415,

    LovesDogs0415 LovesDogs0415 Mar 10, 2014 5:33 AM in response to luisx
    Level 1 (4 points)
    Mar 10, 2014 5:33 AM in response to luisx

    Luis, I absolutely understand because it happened to me when the iOS 7 came out.  I even found a compassionate Apple guy who tried desperately to find me a phone with the old OS.  I had to use the phone and decided I'd just use it for emergency things.  Every other phone type I tried was worse! 

     

    Now I know that this issue is related to more than brightness, but try this.  I turned the brightness down so low that the slider is between "g" and "h" above the words Auto-Brightness on the Wallpapper & Brightness under settings. 

     

    This allows me to use the phones features that I need and I don't have the trouble I used to have with strain and headaches.  Admittedly, this may not work for you.  I am SHOCKED it works for me, but it does.  Brightness adjustments have no effect on any other device and my Apple computer is so old I'm scared.   I am four OS systems back on my computer.  LED lights make me nauseous, and the LED TVs are not an option at all.  I don't go near the TV section in electronic stores and I don't go near the Microsoft store after becoming very ill visiting with my husband to buy his tablet. So many devices with that trigger light source!  So, I am definitely affected by this "phenomenon" whatever it is, but this works for me.

     

    Good luck.

  • by StefanD13,

    StefanD13 StefanD13 Mar 10, 2014 11:55 AM in response to LovesDogs0415
    Level 1 (0 points)
    Mar 10, 2014 11:55 AM in response to LovesDogs0415

    I use as well an iPhone 4 (bought Nov 2010) and is very comfortable to use. Even after the iOS7 update...

  • by Karoozo,

    Karoozo Karoozo Mar 11, 2014 2:57 AM in response to RMartin111
    Level 1 (0 points)
    Mar 11, 2014 2:57 AM in response to RMartin111

    2008 macbook pro led backlit - no issues

    2012 mba - eye strain, headache.

    Where is the problem? Glossy screen?

  • by mvanier,

    mvanier mvanier Mar 11, 2014 1:41 PM in response to Karoozo
    Level 1 (0 points)
    Mar 11, 2014 1:41 PM in response to Karoozo

    Karoozo, you might want to look at the huge backlog of posts in this mailing list to get an idea of the possible problems.  But my guess would be that you are reacting to the spatiotemporal dithering that is a "feature" of newer macbooks, since you've already had an LED backlit macbook that didn't bother you.  If you look at the screen and it seems like the letters are a bit indistinct and the background looks a bit like "snow" (random noisy pattern like on a TV that isn't getting any input) then it's definitely the dithering. If so, the odds are that you will be able to adjust to the new macbook over time; your brain will learn to tune out the dithering.  I'd recommend not using the new macbook for more than an hour at a time until you adjust.  My new macbook caused me intense eyestrain when I got it, and now I can use it all day without problems.

  • by Scott98981,

    Scott98981 Scott98981 Mar 11, 2014 4:45 PM in response to RMartin111
    Level 1 (8 points)
    Notebooks
    Mar 11, 2014 4:45 PM in response to RMartin111

    I found something curious. I have no problems with any iphones on any iOS. However I tried the new iOS7.1 accessibility feature "reduce white point" and instantly it feels like the same eye symptoms I get from other devices like the iPad air. When I turn it off, I'm back to being able to use the iPhone 5 or iPad 3 all day. This suggests to me on some levels at least that the OS can affect the experience we are having. I wonder what the software is doing.

  • by luisx,

    luisx luisx Mar 12, 2014 6:45 AM in response to Scott98981
    Level 1 (0 points)
    Mar 12, 2014 6:45 AM in response to Scott98981

    Where do I find that option? Just upgraded it and can't see reduce white point (my UI isn't in english but still I can't find an equivalent setting)

  • by peter_watt,

    peter_watt peter_watt Mar 12, 2014 11:43 AM in response to luisx
    Level 3 (910 points)
    Mar 12, 2014 11:43 AM in response to luisx

    Settings, General, Accessibility, Increase Contrast,

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