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 Dovez,

    Dovez Dovez Sep 11, 2012 1:43 PM in response to StefanD13
    Level 1 (0 points)
    Sep 11, 2012 1:43 PM in response to StefanD13

    I just think that the information that is sent to the monitor from win 7 at the subpixel level would be lost with an unnative resolution and the same with using a VGA input. My theory says that something at the subpixel level is going on. Perhaps it is, perhaps it is not. Whatever windows 7 is sending to the LCD is definitively lost when you use an unnative resolution, at least I think it is. It's a good theory for now. Well see later what's really going on. Perhaps it's exactly that. Who knows?

  • by CoreLinker,

    CoreLinker CoreLinker Sep 12, 2012 2:07 PM in response to willison
    Level 1 (0 points)
    Sep 12, 2012 2:07 PM in response to willison

    Excellent, informative post willison! You seem to know your eye strain.

     

    Now...

     

    Some you have said you felt improvement using f.lux software and removing the color blue from the spectrum in graphics option. Improvement, but the issue was not completely gone.

     

    I think if there is any harshness coming from the LED because of it's blue peak, that does not completely solve the issue. The LCD matrix itself cannot block all blue light coming from the LED no matter how hard it tries. So I suggest trying special blue-blocking glasses as the next step. And I don't mean the slight amber tint like on the Gunnars, I mean the kind of glasses that make a blue LED almost invisible. Even if you decide you'd rather die than use a computer like that, at least you'll know where the problem lies.

     

    Sorry for not offering any solutions, only ideas, but that's all I got.

  • by StefanD13,

    StefanD13 StefanD13 Sep 23, 2012 1:51 PM in response to CoreLinker
    Level 1 (0 points)
    Sep 23, 2012 1:51 PM in response to CoreLinker

    Bought a Galaxy S3 and when filmed with high speed camera, you can very clearly see black bands running down the screen. Width of the band increases as the brightness is reduced.

  • by FNP7,

    FNP7 FNP7 Sep 26, 2012 5:37 AM in response to Dovez
    Level 1 (0 points)
    Sep 26, 2012 5:37 AM in response to Dovez

    I don't understand why, but changing the resolution on my MBP has made an enormous difference to my experience of eye-strain/ discomfort.

     

    Under 'display preferences', I've changed the resolution from what I think was the default (1440 x 900) to 1344 x 840, and now I can pretty much use the MBP for hours at a time. The text/ image is obviously not quite as sharp as on the default, and I do experience some discomfort after eg all day use, but nowhere near the 15min threshold by which point I suffer when the display is on the native setting. Now, I'm no longer tied to the desktop CCFL display, which is very good news.

     

    I had to play with the display calibration a little to help my eyes see text (at a colour temperature of 4500 I couldn't focus on the text; at 6000, it's fine. I have the gamma set to 2.2. I guess this stuff might be relevant for f.lux users who change their resolution. I don't think brightness is an issue.

     

    Hope this helps - it's worked a treat for me

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Sep 26, 2012 11:21 PM in response to FNP7
    Level 1 (5 points)
    Sep 26, 2012 11:21 PM in response to FNP7

    Thank you very much for your findings FNP7!!

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Sep 26, 2012 11:52 PM in response to Eric Leung1
    Level 1 (5 points)
    Sep 26, 2012 11:52 PM in response to Eric Leung1

    I would like to share a little bit of findings I have noticed recently too.

     

    It seems that the mobile devices manufactured lately generally has uncomfortable LED screens...

    It seems to hold true even if that particular device used to have comforatable LED screens... (i.e. old ones are comfortable, new ones are not)

     

    Here are what I experienced:

     

    I played with a Samsung GS3 for 10 min, and I could already feel it to be uncomfortable...

     

    And then I played with someone's iPad 2 that was bought around last year end. I found that the screen seems to be noticeably less comfortable to look at compared with mine. (mine was purchased early last year when it first launch) Perhaps some thing has been changed during the manufacturing process?

     

    My aunt has bought an iPhone 3Gs a couple months ago, when I helped her checked on a problem last week, I quickly noticed that the screen is also the not too comfortable kind... this further makes me feel that the LED manufacturing process / method might have been changed lately...

     

    Now, I bought the new iPhone 5, and I am a bit disappointed (though not too surprised) to found that I got eye strain, pain, etc. with it too...

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Sep 27, 2012 12:04 AM in response to Dovez
    Level 1 (5 points)
    Sep 27, 2012 12:04 AM in response to Dovez

    Dovez, my apology for my super late reply!

     

    Regarding the test you mentioned about staring at a white screen compared with a black one. I can confirm that when I'm looking at a color inverted screen (white texts on black background) on my MacBook Air, my eyes felt noticeably "easier" when compared with the normal black texts on white background setting.

     

    I could read longer when using the color inverted screen, though it's still quite tiring.

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Sep 27, 2012 12:26 AM in response to willison
    Level 1 (5 points)
    Sep 27, 2012 12:26 AM in response to willison

    Willison:  Since you said you had problem with CCFL displays (displays lit with fluorescent backlight), I suggest having a try with those FL-41 coated glasses.

     

    It's like a sunglass with a rose red coating. The theory behind is to block the blue/green light from fluorescent light that causes discomfort to some people. While I'm not really sensitive to fluorescent light, I do found it to be comfortable when putting it on.

    I purchased my FL-41 glasses through Axon Optics. They can refund (you need to pay shipping though) if you don't find it useful.

    (Disclaimer:  I have no interest with this company! And I don't know if those glasses would help or harm too! What I said is just an honest recommendation based on what I tried Also, it doesn't seem to work with LED displays from what I tried, only CCFL.)

     

     

     

    CoreLinker:  I purchased the above mentioned FL-41 glasses in the hope of cutting the blue from the uncomfortable LED screens, but I'm disappointed to find that while it seems to work with fluorescent lights, it doesn't seem to help me work longer with my MacBook Air... perhaps a even stronger lens in filtering the blue light is needed...

  • by LovesDogs0415,

    LovesDogs0415 LovesDogs0415 Sep 27, 2012 4:58 AM in response to RMartin111
    Level 1 (4 points)
    Sep 27, 2012 4:58 AM in response to RMartin111

    A couple of years ago I had to return my MacBook Pro because of the LED lights.  I can't even use the new iTouch or iPads.  What happens to my eyes has been verified by my opthalmologist.  I thought I understood LCD and LED. I follow this thread.  However, now I am completely confused again.  Here's what happened.

     

    After a visit to the Apple Genius bar to get my MacBook checked out.  It's one of the last with an LCD screen, I was told, born in 2009.  On the way out I stopped to take a quick peek at the new machines.  I say quick because even a few minutes in the added glare of the store sometimes leaves me with red eyes and a little headache.  I go to a MacBook Pro and happen to select About this Mac and look at the Display info and it says, "backlit LCD."  What???   I check another machine, even one with retinal display and it says the same thing.   I ask a Apple employee and he says they are all LED.  He has no idea why it says backlit LCD.  He and I find a manager.  No clue.  We ask another employee.  "I don't really understand the difference between LED and LCD."  I was aghast.  Here we are out here suffering and the damned Apple employees don't understand the difference?  No one could explain and they all look dumbfounded.  I felt foolish for trying to be so loyal, but Apple computers are so superior. 

     

     

    Anyway, the first person I asked promised to track down the answer and call me.  We'll see.  I figure someone here knows.

     

    Please help me.  I trolled the thread for answers, but couldn't quite get it.  What does this mean LCD backlit?  Still LED?  Does this offer any hope for those of us whose eyes can't tolerate the LED backlit screens?  I did not think that LED and LCD could co-exist.

  • by dmdimon,

    dmdimon dmdimon Sep 27, 2012 5:13 AM in response to LovesDogs0415
    Level 3 (840 points)
    Sep 27, 2012 5:13 AM in response to LovesDogs0415

    Backlit LCD stand for LCD display with supporting light from back side. Nothing is told on source of that light. It can be CCFL or LED or even tungsten lamps or torch - the thing still will be a backlit LCD.

  • by LovesDogs0415,

    LovesDogs0415 LovesDogs0415 Sep 27, 2012 5:33 AM in response to dmdimon
    Level 1 (4 points)
    Sep 27, 2012 5:33 AM in response to dmdimon

    So the LED screens (LEED that Apple is so proud of are backlit by LCD?

     

    The internet says this:  Retina display: 15.4-inch (diagonal) LED-backlit display with IPS technology; 2880-by-1800 resolution at 220 pixels per inch with support for millions of colors.

     

    But the computer itself said Backlit LCD on display information.

     

    Thanks for reading and responding.  Sorry to be so obtuse. 

  • by dmdimon,

    dmdimon dmdimon Sep 27, 2012 5:45 AM in response to LovesDogs0415
    Level 3 (840 points)
    Sep 27, 2012 5:45 AM in response to LovesDogs0415

    So the LED screens (LEED that Apple is so proud of are backlit by LCD?

    exactly vice-versa : LCD (liquid cristal display) is backlit by LED (light emitting diode)

    So nothing wrong with backlit LCD - it is lit from backside by LED (or something else).

     

     

    Retina display: 15.4-inch (diagonal) LED-backlit display with IPS technology; 2880-by-1800 resolution at 220 pixels per inch with support for millions of colors.

    IPS Is just one of (and good one) variant of LCD. So message is the same - LCD lit with LED

  • by Dovez,

    Dovez Dovez Sep 29, 2012 2:27 PM in response to Eric Leung1
    Level 1 (0 points)
    Sep 29, 2012 2:27 PM in response to Eric Leung1

    Eric, I have a theory that you would have no prolems looking at a completely white screen of your problematic device. Inverted colors are not quite the same as a black screen and a completely white screen isn't exactly the same as using the screen in normal mode. This experiment would help me understand this problem better.

  • by Eric Leung1,

    Eric Leung1 Eric Leung1 Oct 2, 2012 8:26 PM in response to Dovez
    Level 1 (5 points)
    Oct 2, 2012 8:26 PM in response to Dovez

    Dovez, for my eyes, a completely black screen feels easier to look at than a completely white one.

     

    And if I'm watching full screen videos on the screen, my eyes are a lot more toleratable to it too. It seems if I'm not concentrating on reading texts, it's relatively less hurt to the eyes. Not sure if that helps your theory.

  • by Dovez,

    Dovez Dovez Oct 3, 2012 2:58 AM in response to Eric Leung1
    Level 1 (0 points)
    Oct 3, 2012 2:58 AM in response to Eric Leung1

    Thanks Eric. I'll have something to think about with the results. Did the white screen feel just as bad or worse (better?) than when you have normal content on the screen, like when reading internet sites? It seems that you have problems with the backlight rather than with the screen, but I'm still not completely sure. I final experiment would solve this: a transparent matte plastic bag over the screen with a white screen would diffuse all of the screen content and would leave only diffused light entering the eyes, just like the experiment with the light boucing of the wall I suggested. With this, all of the properties of the screen would be dismissed, leaving only the properties of the backlight. If you had no problems with a white screen and a diffuser bag, then the properties of the screen are to be blamed. If the opposite is the case, then it's the LED's fault. I'm not saying you have to try this, but it would give us data to work with in solving what the cause for the eye problem is.

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