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  • Dovez Level 1 (0 points)

    My view: These are neurological flicker symptoms. PWM flickers and newer hardware combined with newer drivers makes the LCD pixels flicker in a snowy fashion. Snow is hard to detect because the light gets somewhat mixed. One would have to measure a single isolated pixel for flicker in a PWM-free monitor that causes flicker symptoms to be able to detect the snow flicker if it was there.


    Some people have both flickers present in their devices, some one, some none. PWM duty cycles and frequencies play a role.


    Flicker puts a certain load on certain parts of the nervous system. Strong people can deal with that load, but for some it is too much and the body tells them to stop exposing themselves to the harmful light by causing symptoms. Pain serves that function.


    Blue light contains much more data for the system to process than red light. The brighter the light entering your eyes, the more data comes in that needs to be processed. That is why filtering the blue light and dimming the light without PWM takes off some on the load on the nervous system, but doesn't solve the problem. Flicker is so the key role here that by removing it other factors would hardly play a role. Exceptions are persons with real eye disorders.


    Many light sources flicker with problematic 120Hz/100Hz (twice the mains frequency). Many light sources use electronic ballasts and the kHz are too fast to create problems. These same electronic ballast lights cause strong problems by flickering within the problematic Hz numbers whenever they don't get enough voltage or are nearing the end of their lifespan without the flicker being visible to the naked eye for a long time.


    Many will disagree with what I write and my current view may not be the real problem, but it's the best conclusion I can make with the data I have. I have read about people seeing the snowing pixels by looking at the screen closely from a certain angle. The smaller the pixels, the harder to see/detect the snow. Retina displays disguise it most successfully. Pixel flicker seems to have been introsuced at about the time PWM got removed from the backlights of Apple products (Slightly after LED bcklighting was introduced). Just something to think about.

  • iobe Level 1 (0 points)


    that's pretty much my experience as well. I could see the "snow effect" you mention with the two screens I've had problems with: my retina MBP and in boot camp Windows with my older MBP.


    The fact that the 2011-MBP is absolutely fine for my eyes (and no snow) in MacOS but causes problems when I boot into Windows makes me wonder if there is a software solution to this problem. The only difference is the OS and driver.

  • logoo88 Level 1 (0 points)

    Yes, I can see the snow effect as well and I presume it has a role in what we experience.

    But what's weird is that my HP pavilion g6 laptop has both a LED screen and the snow effect (on windows 7). And I'm fine with it. But frequency and spatial organisation of the flickering are probably different.


    One should try to put windows XP/vista on a problematic Apple Laptop (I don't know if it's possible?) and see what happens because the first windows known to handle the Snow effect is 7

  • David Turnough Level 1 (0 points)

    I remarked the other day at work how 'noisy' the HP ElitePad's screen is. On a white screen there is noticable coloured noise. It was visible to others too, others I might add who are not effected by the LED issue.

  • Anastasia80 Level 1 (0 points)

    My eyes have recently started being sensitive and feeling tight. I work with an iMac (it's old-doesn't have an SD slot), and have a iPhone and recently upgraded my ipad2 to a mini.


    I'm wondering if my mini has exacerbated an underlying problem, because I've only just noticed it. I'm not using devices more often.


    I work in IT, am studying online and gererally have a paperless existence, but this is totally ruining it for me. To make things worse, I am addicted to my devices. I actually wrote on a piece of paper last week and immediately lost it! How am I going to cope? Having an app for everything certainly isn't helping!


    Is this the new asbestos? Are we all going to go blind?

  • Jessiah1 Level 1 (0 points)

    It may not be a recent development for you and you may just be sensitive to LED back lighting like many of us. Your new MINI is LED back lit, I am not sure about your IPAD 2 but I think it may not be if it never caused you discomfort before? Someone else here will know for sure, I know the MINI is LED back lit because I was going to buy one for my wife at Christmas and when I told her it was LED and would make me sick she said she didn't want it if she couldn't use it sitting next to me....

  • Gurm42 Level 1 (0 points)



    I think we need to differentiate here between LED and "new, high-intensity, low-power LED's".


    Your iPad2 uses the former. Your iPad Mini uses the latter. Both are LCD displays, backlit by LED. But one of them is hurtful to look at. (Guess which?)


    I have no problems with LED panels from 2010-2011, but the newer ones hurt after just a little while.


    - Gurm

  • Gurm42 Level 1 (0 points)

    So this week I'm at a major technical conference. The GOOD news is that my eyes haven't completely bugged out. The BAD news is that I just can't play with any of the new toys. The large-size touchscreens are vaguely tolerable (but not for long periods) but the smaller touchscreens are terrible. Yesterday I had the option to try a new phone - the Nokia Lumia 928, it's really an amazing device. The verdict is still out, but my eyes were tired when I tried it.


    The new tablets here (Surface) are tough to use, but again verdict is out until I have fresh eyes. Maybe after my midday siesta today I'll give them another go.


    The good news is that awareness of this problem is growing. One of my friends who I'm with turned to the other friend - who I hadn't caught up with in years - and said "has he told you about his LED sensitivity problem lately"?


    The other friend - who had not heard of this from ME - said "oh, you mean LED's newer than about 2 years ago? Lots of people can't use them... they changed the light or something". So people know about it - or are starting to!


    - Gurm

  • Jessiah1 Level 1 (0 points)

    That's fantastic news Gurm that other people are becoming aware of this issue, still lots of work to do in order to fix it I'm sure. It sounds like if I was at the same conference I wouldn't be doing well at all, I also wouldn't recover enough within hours to understand if any of the monitors were better than others. There is definitely a big difference in the level of sensitivity between folks with this issue.

  • Kxtr73 Level 1 (0 points)

    Today I have removed myself PWM brightness control from new TV/monitor AKAI 32' AKFL3274HF3 on CCFL bulbs

    It have: 32' LG 1920x1080 with passive LG 3D with no visible input lag and good viewing angles. (IPS ?). I don't recognized disturbing flicker in most tests from:



    In comparision to 24' ACER G245h which was comfortable to my eyes: 2 CCFL edge monted bulbs with no PWM flicker by turned on 100% brightness, AKAI has: unknown number of CCFL bulbs behind screen and constant (smaller or lower) PWM flicker on all settings. Any colour shifting, brightness and even many good eyeglasses + window with three glasses before screen failed to protect against eye fatigue and pain in the right eye.


    Before removing PWM camera showed flicker even with 100% backlight. It looked like noise.


    So I opened the TV. And disconnected brightness control wire from main board to inverter build on OZ9966SN chip.


    There is no brightness control now, but dimming by monitor contrast has very wide level. A screen finally is super stable. Camera shows nothing like in ACER monitor.


    I can't say how this will work for my eyes now, becouse I have a pain from yesterday day. So removing PWM from CCFL/LED monitors and TV could be very easy.

  • Gurm42 Level 1 (0 points)



    Yes there absolutely is a huge differential in symptoms. In fact, there's a difference in symptoms within the SAME individual sometimes. If I take a week off from work, rest my eyes, mostly stay at home or outside during the day, with incandescent lights and no dodgy screens or lighting... then my tolerance for bad screens and fluorescents is HUGE. Like hours and hours without issues.


    On the other hand, if I'm having a particularly bad day of symptoms, come home and overtax my already tired eyes, and then have to go back to the office a second day in a row... then it is exponentially worse!


    These symptoms are EXTREMELY similar to eyestrain symptoms, but aren't caused by the same thing (overworked eye muscles). Even some of the itching/stinging/burning people experience are classic eyestrain-related symptoms. This leads me to hope that there will be a "fix" for this sometime in the near future.


    I've been at this conference for 5 days now, and I'm discovering that the latest phones and monitors aren't AS bad. I think that manufacturers may be (finally) leaning away from the bright blue lights. Or maybe it's just that lots of things have anti-glare or are behind layers of glass and digitizers.

  • Jessiah1 Level 1 (0 points)

    Interesting, believe it or not I cannot tolerate LED light of any kind for any period of time, 10-15 seconds and its down the rabbit hole for me. My symptoms are greater than eyestrain and Migraine though, my neurologists are trying to figure out what's going on with me, they feel so far it is light triggered migraines however they have not ruled out some type of seizure disorder or something like that. I wish I could even just drive at night without getting sick from LED tail lights, sounds like you can get through that kind of exposure just fine. The only difference for me is if I am away from the lights for a period of time than I can get away with a glance here and there of LED light, its compounding each time I get exposed within a 24hr period and doesn't go away sometimes for 2-3 days after a few minutes of exposure. Sometimes I feel like there is no one else out there as sensitive as me but I am sure there is.

  • David Turnough Level 1 (0 points)

    I had a Vistual Field test for Glaucoma as part of my eye exam. It was basically a red LED matrix which would illuminate a single LED and I had to hit the button when I saw it. After images made this very difficult, I struggled to distinguish between the illuminated LEDs and the after glow. I felt very disorientated prior to going in for the main VA exam. Also, any idea what type of light they use in the hand held Retinoscope? It took a couple of mins to get my eyesight back before the test could continue.

  • cameronreilly Level 1 (0 points)

    I'm glad I just discovered this thread. For the last couple of years - since I bought my 2010 17" MBP - I've been getting headaches after 3 or 4 hours of continual work. I need to take a break (and a few ibuprofen). I thought it might be my eyes but they check out fine. I also don't get it on my MBP while watching movies, only when I'm working and the screen is bright.

  • cadette61 Level 1 (0 points)

    I'm now on my second external CCFL monitor (with HP Envy 4 laptop) and I'm still having some problems. The first monitor (an iiyama) was definitely worse, but the new one (Asus vh242h), while better, is not entirely comfortable. I'm getting dry eyes and the screen (which is matte) just seems a bit garish. Which leads me to think: might this be caused by the OS? I'm using Windows 8. Perhaps its colours are just too much for me, its whites too bright? Never had an issue with Vista in this regard. I'm connected via HDMI, screen resolution is 1920x1080 (native). Am currently experimenting with monitor brightness set to 100% and brightness/contrast reduced on the graphics card, but not sure it's making any difference.


    Hard to know where to go from here. Change the OS? Am even considering buying a 6-year old Macbook and sticking an SSD in there, but that seems like a rather desperate measure. But...current Macbook Pros give me big problems (headaches, dry eyes), LED Windows laptops are hard for me to look at, and even now using an external CCFL with Windows 8 I'm not comfortable.

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