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 dj_rag,

    dj_rag dj_rag Nov 13, 2012 5:15 PM in response to mvanier
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    Nov 13, 2012 5:15 PM in response to mvanier

    thanks so much mvanier.....I'm seeing that as we speak (about the heavy anti-glare coating) on some reviews on amazon. does seem to be a bit of a problem.

  • by dj_rag,

    dj_rag dj_rag Nov 13, 2012 5:18 PM in response to mvanier
    Level 1 (0 points)
    Nov 13, 2012 5:18 PM in response to mvanier

    sorry for my ignorance - so does adjusting blue levels make things easier on the eye? what kind of settings would you recommend I adjust to?

    In just the 15 minutes I tried, I found the default brightness (50%) incredibly bright...I took it down to 30% or so and it still seemed very bright...perhaps as I'm just not used to such large screens...

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Nov 13, 2012 6:44 PM in response to dj_rag
    Level 1 (5 points)
    Nov 13, 2012 6:44 PM in response to dj_rag

    From the CCFL displays I have used so far, I think they are not causing problems to my eyes in terms of blue intensity.

  • by mvanier,

    mvanier mvanier Nov 13, 2012 7:45 PM in response to dj_rag
    Level 1 (0 points)
    Nov 13, 2012 7:45 PM in response to dj_rag

    I have heard that both the Dell U2711 and the U2410 are extremely bright.  Looked at in one way, this is a good thing, because you can turn the brightness way down and the CCFL tubes will last a long time.  So do that!  You may have to recalibrate the colors at the right intensity, though.  Also be aware that current CCFL monitors give better color reproduction than the standard LED-backlit ones, which is why many graphic designers prefer them.

     

    As for blue light, I'm not an expert by any means, but in my reading and experimenting it appears that blue light causes a bunch of problems.  First off, the cones in your fovea (the part of your eye responsible for the finest vision and most of your color vision) are supposedly less sensitive to blue and more sensitive to red and green light.  Therefore, if you have a lot of blue light in the backlight, it's hard to focus on it, and your eyes will continually focus and defocus in a vain attempt to lock onto the image.  That leads to severe eyestrain.  So goes the theory, anyway, and to back it up I've used the f.lux program which allows you to cut blue light levels by a very large amount. Almost immediately I noticed a significant reduction in eyestrain, as many here have reported.  Also note that good old incandescent light (which is what most people prefer to read by) has almost no light in the blue spectrum at all!  CCFLs have a lot more blue (their "color temperature" is higher), and LEDs are... interesting.  There are different kinds of LEDs.  The standard white LED that is used as the backlight in 99.99% of LED-backlit monitors (I only know of one exception, the HP Dreamcolor which uses RGB LEDs and is insanely expensive) is actually a blue LED with a yellowish "phosphor", or chemical coating.  This creates a color spectrum which has a huge peak in the blue region and a more spread-out peak in the yellow region.  The eye perceives this as white, but all whites are not alike.  In my opinion, the big blue peak in LED backlights is the source of much (most?) of the discomfort people report here.  CCFLs have a lot of blue, but nothing remotely as bad as LED backlights.  And to confuse things even more, different LED backlights seem to have different amounts of blue, suggesting that the amount of yellow phosphor on the LEDs is not regulated very precisely.  You could have (for instance) one iPhone which looks a tad yellowish but is very easy on the eyes, and another which has a much more vibrant blue but hurts your eyes.  I know because that was exactly my experience.  There is also the issue of flicker, but at least with recent iPhones I can detect almost no flicker at all; the screen is incredibly stable looking.  BTW iPhones also have an accessibility feature wherein you can set the video to reverse video; this can be helpful when looking at web pages with a white background.  You can also set up the phone so a triple-tap on the button invokes reverse video.

     

    Most of this information is in this discussion thread, so consider this a summary with my own opinions added :-)  As for configuring the U2711, I'd go into the on-screen display (OSD) and change the color temperature down to around 5000K or below and see if it helps.  There are more sophisticated configurations you can do with that monitor (actually, it's incredibly configurable) but that should give you an idea if cutting blue light helps.  Or just try the f.lux program, which doesn't require any tweaks to the monitor.

     

    Hope this helps!

  • by dj_rag,

    dj_rag dj_rag Nov 13, 2012 8:25 PM in response to mvanier
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    Nov 13, 2012 8:25 PM in response to mvanier

    Incredible info Mvanier, thanks so much for this summary, i'm sure it will help a lot of people here...lot of interesting theories here to investigate!

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Nov 13, 2012 8:37 PM in response to mvanier
    Level 1 (5 points)
    Nov 13, 2012 8:37 PM in response to mvanier

    mvanier, great summary! Agree with what you said!

     

    Just a small thing to add regarding the professional CCFL displays. Some of them may not perform very well (less color reproduction ability) when the monitor is set at a too low brightness.

    And a more important thing is that the backlight's PWM ill effect might kick in if brightness is too low. I have experienced that in both the EIZO and NEC that I have used for some time. I needed to raise the ambient light level so that the screen can be set to be above 25% brightness.

  • by mvanier,

    mvanier mvanier Nov 13, 2012 9:59 PM in response to Eric Leung1
    Level 1 (0 points)
    Nov 13, 2012 9:59 PM in response to Eric Leung1

    Eric, I see your point about color reproduction.  Oh well, nothing is free!   One thing about PWM: CCFL PWM is much less irritating than typical LED-backlight PWM; it's a softer transition between on and off (more of a sine wave than a square wave).  I use an old Apple CCFL Cinema Display, and it's pretty good even at low light levels.  But of course, everyone's sensitivity is different.  I've also noticed that my new iPhone 4S, which hurt my eyes like a son-of-a-gun when I just got it, now doesn't bother me much, leading me to believe that the eyes can adapt to LED backlights to some extent with some people.  However, I wouldn't want to try it with a full-on LED monitor!  In my opinion, the solution will come from new technologies, possibly including newer/better LED backlights or non-backlit screens.  However, the comments I've read in this discussion about AMOLED screens (which are not backlit at all) have not been encouraging.  Front-lit screens like the Kindle Paperwhite might also eventually be an option, but they're currently way too slow for regular work.  But it does seem to me that the display industry is hopping with new ideas, so hopefully we can all hang in there with CCFL monitors until something decent comes around.  Until then, protect your eyes!

     

    I would also love to hear from anyone who has used the HP Dreamcolor monitor (something like $3500 if you can believe it).  This has RGB LED backlights (independently adjustable red/green/blue LEDs) which supposedly give great color reproduction.  My question is if this monitor is easier on the eyes than regular LED-backlit monitors, or even than CCFL-backlit monitors.

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Nov 13, 2012 10:31 PM in response to mvanier
    Level 1 (5 points)
    Nov 13, 2012 10:31 PM in response to mvanier

    I guess I have become super sensitive to the discomforts on monitors after feeling seriously ill and realizing the problem around a year ago, hahaha.

     

    CCFL's PWM is surely much more easier to the eyes. Though for me, it seems it's starting to get a little uncomfortable when the brightness go too dim (but still better than looking at a LED!).

    So, for those with very sensitive eyes, I guess it's better to keep the ambient light up so that you may avoid the potential PWM problem by bringing the screen brightness too low

  • by Rabby Zhang,

    Rabby Zhang Rabby Zhang Nov 14, 2012 5:05 PM in response to RMartin111
    Level 1 (0 points)
    Nov 14, 2012 5:05 PM in response to RMartin111

     

  • by Rabby Zhang,

    Rabby Zhang Rabby Zhang Nov 14, 2012 5:33 PM in response to RMartin111
    Level 1 (0 points)
    Nov 14, 2012 5:33 PM in response to RMartin111

    Hey everyone, I’d suggest you try this Ipad app which solves this problem.  Basically, it shuts down the screen if the kid got too close to Ipad screen.

     

    https://itunes.apple.com/us/app/kids-videos-with-eye-care/id561377046?ls=1&mt=8

     

    The world’s only kid’s video app with eye vision protection.

    If the child is too close to the screen, video will be paused. Experiment shows that, after using the app for a few days, children will quickly learn to watch TV and IPAD video from an healthy distance.
    1Patented and world’s only app with eye protection feature. Cutting-edge technology based on facial recognition algorisms.2Great selection of cartoon contents for kids age 1-6. Over 60 titles available and adding new contents weekly. You can also use this app to access video sites like Youtube.3Easy to use and easy to setup.4Parents can monitor which video the kid was watching.5Parents can set time limits for watching video.

  • by CoreLinker,

    CoreLinker CoreLinker Nov 15, 2012 5:51 AM in response to Rabby Zhang
    Level 1 (0 points)
    Nov 15, 2012 5:51 AM in response to Rabby Zhang

    Yes, Rabby, thank you. This indeed solves all of our problems. I have been talking with the people here and they have all reported immediate relief of eye strain and other symptoms.

     

    We also want to say that we're enjoying the cartoons very much and especially like the time limit feature as it helps us get ready for bedtime.

     

    WE SHALL BE FOREVER GRATEFUL TO YOU!

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Nov 16, 2012 7:20 AM in response to Eric Leung1
    Level 1 (5 points)
    Nov 16, 2012 7:20 AM in response to Eric Leung1

    Today I have a chance to play with one of the least toublesome iPhone 5 screens for a longer period of time.

     

    What I found is that while it is quite a bit more comfortable to use compared with the one I own, the discomfort still exists and accumulates. So, eventually my eyes still don't like it

     

     

    May I know if any one of you have tried the iPhone 5 and feel the screen to be hard to look at?

     

    I have looked around the web, it seems there are a few reported cases, but most of them don't seem to have much follow-up since most other people are happy with the screen and kind of ignored the cases.

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Nov 21, 2012 1:28 AM in response to Eric Leung1
    Level 1 (5 points)
    Nov 21, 2012 1:28 AM in response to Eric Leung1

    I guess my posts may have put off many people here to try the iPhone 5...

    Well, I think it's really a nice phone if your eyes are ok with the screen (in fact, a lot of people are ok with it!), it's no harm giving it a try

     

    By the way, I was checking around the web recently for information on the iPad mini, and it seems it is causing headaches to a number of people. While people are mostly blaming on the resolution / glare / screen size, I suspect its screen has similar issue as the iPhone 5, but I haven't confirmed that myself.

  • by SimonStokes,

    SimonStokes SimonStokes Nov 21, 2012 3:31 PM in response to RMartin111
    Level 1 (0 points)
    Nov 21, 2012 3:31 PM in response to RMartin111

    Today I have had a bit of a revelation. I am a music production teacher and have been suffering with motion sickness, headaches and migraines from my Macbook (Late 2011) ever since I got it. I have the hi-res screen (model number LP154WE3-TLA2).

     

    I noticed today that two of the people that I teach had Macbooks which looked completely different to my eyes. Both are Early 2011 models and both have screen model number LP154WP4-TLA1. Now, here's the question: if I purchase this model of screen (available on eBay for roughly £65), can I swap out my high resolution screen (and presumably re-sell it) and replace it with this one?

     

    Any information would be greatly appreciated - I notice that in the eBay listing it states that you should not up- or donw-grade your screen resolution, is this gospel?

     

    Thanks for any information, a solution could be nearing for me..

     


  • by dj_rag,

    dj_rag dj_rag Nov 21, 2012 3:42 PM in response to SimonStokes
    Level 1 (0 points)
    Nov 21, 2012 3:42 PM in response to SimonStokes

    I'm sure someone more tech savvy will make more sense of my post for you, but I looked into this before, as I really want today's power in a laptop with a screen from back in 2007/8! (a CCFL screen much easier on my eyes) however I found a useful screen replacement website that i'll try to find the link for you ...that explains you cant mix n match screens - hope i'm not saying things you already know but if not basically laptops are built nowadays for their screens, so a certain model designed for LED can only have a LED backlit screen for example, and cant be replaced with a screen of a different technology.  so you might be able to change but I dont think you can mix n match technologies....I wonder if you can replace a glossy with a matte screen though? (that might be more relevant to your original question? I'm sure someone on here will know the answer to that)

    The site, if i can find it again, were really helpful anyway and got back to me really quick about my queries...I asked them which mac ever built were CCFL and they were happy to help even though there was no potential business in it for them.

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