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 stylinexpat,

    stylinexpat stylinexpat Feb 14, 2010 8:59 AM in response to RMartin111
    Level 1 (14 points)
    Feb 14, 2010 8:59 AM in response to RMartin111
    I also have been getting severe eye strain and headaches recently from using my Macbook Pro. I was considering getting rid of this one and getting a regular Macbook instead of the Macbook Pro. The regular macbook seems to have less glare from he screen.

    Any thoughts..?
  • by thisisit,

    thisisit thisisit Feb 24, 2010 11:12 PM in response to stylinexpat
    Level 1 (0 points)
    Feb 24, 2010 11:12 PM in response to stylinexpat
    I don't think it's the glare that causing the problem. I used a Mac Book pro with Glossy screen for some time, and suffered from the eye strain symptoms described in this thread. I've since purchased a Mac Book with a matte screen, and no difference, I still get terrible eye strain when using the laptop. So I primarily use it with an external LCD screen now with no issues.

    It's all together possible a Mac Book would be different for some other reason.

    I cannot pin down what causes this eye strain after looking at what seem to be the 4 main potential causes Glossy (i don't belive it's this given my experience with the matte screen), LED Backlight Flickering as part of the dimming process, Brightness or the amount of Blue light from the LED Backlight.

    I am suprised given the number of people that seem to have this problem with the LED Backlit screens that no one has a real answer.
  • by BSteely,

    BSteely BSteely Feb 25, 2010 8:38 PM in response to thisisit
    Level 5 (7,635 points)
    Feb 25, 2010 8:38 PM in response to thisisit
    I have an interesting update to offer. Apple may be listening to us. I just purchased, in January, a new 15" MBP. When I go into Display Preferences and view the color profile, the panel is listed as a 9CA4. This is a glossy panel. I can tell from other sources that this panel is made by Samsung.

    Anyway, what I wanted to share is the fact that the chopper circuit that controls the LED backlight dimming is operating at a far higher frequency than have been previous versions of LED backlit panels in Apple's notebooks. In fact, it looks to my eyes to be an order of magnitude higher, which would mean higher than 3 kilohertz switching. This is really good news. The frequency is so high that normal phosphor decay dominates the operating characteristic of the white LEDs in dimming mode, and not the switching frequency as was the case before. That puts LED backlit LCDs much more on par with previous generation CCFL backlit LCDs, and perhaps even better than, at least with respect to this particular type of flicker.

    If people really were suffering ill effects from the lower blinking frequency of the LEDs before, then the new ones should start reducing the number of complaints about eyestrain, headaches, dizziness, nausea, etc. that have been seen on these discussion forums. Time will tell. But I'm really encouraged by this development. Someone is listening somewhere.
  • by rgrodevant,

    rgrodevant rgrodevant Mar 8, 2010 9:31 AM in response to RMartin111
    Level 1 (10 points)
    Mar 8, 2010 9:31 AM in response to RMartin111
    Fwiw, I had a 15" MBP purchased April 21, 2008; with a matte screen (my preference). For the first year and a half, I assumed it had a CCFL backlight.

    I have a seizure disorder, and I want to preface this by saying that there is nothing uniquely triggering about the MBP, as far as screen glare inducing "halos" and "auras" and migraines -- I can't use a CRT (I can see some of them rolling out of the corner of my eye), I avoid watching television, I can't stand flourescent lighting, you get the picture. What I did notice was that browsing web pages or using textedit, or any app with a lot of white real estate on the screen, was intolerable for long periods of time, probably moreso than any laptop I've owned yet. I had to keep the screen brightness to a minimum, use a dark desktop image, etc. I have just assumed that its "me" because of my longstanding sensitivities.................

    I only learned it was an LED backlight when it went in for service and the array at the bottom was replaced a few times for vertical streaking.

    Purely anecdotal here but I now have a 15" MPB purchased December 16, 2009, also with LED backlighting. It has a glossy screen, which I dislike -- I miss the matte screen -- but that is the worst thing I can say about it. So far (March 2010) I cant recall a single incident that I've had to walk away from the computer or shut it down and resume working later because of blindness / auras / etc.

    No vertical "stage lighting" effects and other issues I had with the 4/2008 MBP either so I'm guessing they're making improvements as they go along. This is "new" tech for Apple, I'm going to guess they do care and that they do pay attention to this issue.
  • by EdgarMarsalla,

    EdgarMarsalla EdgarMarsalla Mar 10, 2010 1:40 AM in response to rgrodevant
    Level 1 (0 points)
    Mar 10, 2010 1:40 AM in response to rgrodevant
    I own a MBP early 2008.
    I had never noticed a flickering on my screen.
    After I've read this forum I made the test on http://www.lagom.nl/lcd-test/inversion.php and I realized it flickers (just in one test (4a)

    I want to buy an external monitor.

    I would like to know if the flickering is about the MBP screen o the video card.

    I mean, with an external monitor, will I still see a flickering?

    Thank you
  • by Jeffason,

    Jeffason Jeffason Mar 10, 2010 1:48 AM in response to EdgarMarsalla
    Level 1 (40 points)
    Mar 10, 2010 1:48 AM in response to EdgarMarsalla
    when i scroll every single one of those flickers on mine....not so much with 6a/b but it still does a little i think

    when the screen is stable, 4a or b flickers

    Message was edited by: Jeffason
  • by EdgarMarsalla,

    EdgarMarsalla EdgarMarsalla Mar 10, 2010 12:29 PM in response to Jeffason
    Level 1 (0 points)
    Mar 10, 2010 12:29 PM in response to Jeffason
    Could anyone confirm me if the flickering is caused by the LED screen or the video card?
    If it's the screen I'll buy an external monitor


    Thank you
  • by EdgarMarsalla,

    EdgarMarsalla EdgarMarsalla Mar 11, 2010 6:58 AM in response to EdgarMarsalla
    Level 1 (0 points)
    Mar 11, 2010 6:58 AM in response to EdgarMarsalla
    Nobody can tell me if it's the LED screen or the video card?
    I would like to buy an external monitor and I would like to know

    Thanks
  • by BSteely,

    BSteely BSteely Mar 13, 2010 5:17 PM in response to EdgarMarsalla
    Level 5 (7,635 points)
    Mar 13, 2010 5:17 PM in response to EdgarMarsalla
    Those particular test patterns flicker because of architectural requirements for driving LCD screens having nothing to do with LED backlights. So an external monitor will show the same flicker regardless of the type of backlighting used and regardless of the video card.
  • by Howard_9xg3,

    Howard_9xg3 Howard_9xg3 Apr 21, 2010 9:16 PM in response to BSteely
    Level 1 (0 points)
    Apr 21, 2010 9:16 PM in response to BSteely
    I tried a Macbook Air about a year ago and experienced the same problems. In spite of my best attempts to resolve -- lighting, dimming the screen, putting a filter on it, getting the 'shades' application, etc., nothing worked. I was really bummed. The problems were pretty severe....I couldn't last 30 minutes on the machine.

    I had to go back to an old Dell laptop with an LCD/CCFL backlighting.

    I remembered this forum thread from back then too, and I recently checked it to see if there was any good news. I read the most recent posts from the person with the seizure disorder and the person who checked the 'chopper' circuit and was encouraged. I decided to give a mbp another shot.

    Long story short, whatever they did between then and now works, at least for me. I am writing this after having sat at my new mbp for 15 hours and my eyes are fine. I'm really really grateful this got fixed. I hope it works for others.
  • by apple.gaurav,

    apple.gaurav apple.gaurav Apr 23, 2010 11:28 PM in response to noelsmart
    Level 1 (0 points)
    Apr 23, 2010 11:28 PM in response to noelsmart
    I just bought a new MBP 13.3 inches and started using it for more than 3-4 hrs a day. I started feeling headaches and motion sickness kind of feeling. Till today, I could not pin point what was causing it, in fact I also visited emergency one day just because I started feeling throwing up after coming home and felt terrible.

    After reading this article today, I felt like I have some clue about the issue. I have faced similar problems with computer monitors in the past and I know my eyes are sensitive, but I liked the colors of the LED backlit MBP so much I decided to move to mac.

    I have also ordered a matte finish filter for my Macbook thinking that might solve the problem, but until now I was trying to reduce the screen brightness and thought it will going to fix the issue. I will going to now increase the brightness as suggested by this post and see if this solves the problem. I am still under 14 days return period. I just hope it fixes the problem because I just love my new Macbook Pro.

    Thanks for this great post. I will update this if it resolves my issue.
  • by BSteely,

    BSteely BSteely Apr 24, 2010 7:51 AM in response to apple.gaurav
    Level 5 (7,635 points)
    Apr 24, 2010 7:51 AM in response to apple.gaurav
    apple.gaurav, I'm sorry to hear about your troubles. It sounds like Apple have not rolled out higher blinking frequency of the LED dimming control circuit across their whole product line. In that case, any enthusiasm about the improvement is premature, even though an improvement has been observed in some of Apple's notebook products. Message to Apple: Fix them all!
  • by Andrew Tallon,

    Andrew Tallon Andrew Tallon May 10, 2010 1:20 PM in response to RMartin111
    Level 1 (95 points)
    May 10, 2010 1:20 PM in response to RMartin111
    Add me to the list. Just got the latest MBP i7 15inch with the hi-res matte screen. And I can't bear to look at it for very long. If I set the desktop to a basic blue, it appears to 'swim'--the pulsation is quite evident. A local tech thought I would be well to send it back, which of course I'd rather not do, but I'm not sure I'm going to be able to get used to this...
  • by sb32,

    sb32 sb32 Jun 11, 2010 11:42 PM in response to RMartin111
    Level 1 (0 points)
    Jun 11, 2010 11:42 PM in response to RMartin111
    I also traced my headaches to the backlit displays on my macs. We bought an imac and mbp abt three months ago and it wasn't long after that I started getting headaches. I work on dual screen LCDs for 60 hours a week and never experienced headaches.

    Fonts all appear to me as though they are blurry, to accommodate someone with less than perfect vision. I have better than 20/20 vision and can't stand the blurry fonts on my macs. Turning the brightness up seems to make the txt less blurry, probably because my pupils are shrinking to the point I can't see with the precision I'm accustomed to. None of the cleartype settings helped either. Forgive the rant, hope this helps someone if they experience similar issues.

    I would elaborate more but I'm getting a headache as I write this :-\
  • by prestoncrawford,

    prestoncrawford prestoncrawford Jun 16, 2010 4:27 AM in response to sb32
    Level 1 (0 points)
    Jun 16, 2010 4:27 AM in response to sb32
    Is there any difference between a MacBook and a MacBook Pro? I picked up a MacBook Pro a couple of days ago but the aluminum cut into my arms and it caused finger pain typing on the keyboard. I returned it and picked up a MacBook. The MacBook is much better, but the display just seems "off". I'm not sure what it is. Compared to my old LCD and my current (2009) HP Laptop the screen really pops. But it seems kind of "wrong" or off. I don't know what it is. Like the whites are too white and the blacks are too black. Is this part of the phenomenon of the LED being different from an LCD monitor?

    I checked the model number of my display and I don't have the Samsung mentioned earlier. I have an LP133WX2-TLC7. Hopefully I'm going to be okay with that. Right now the monitor seems strange. Like I can't quite focus on the text the way I usually can.
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