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  • David Turnough Level 1 Level 1 (0 points)

    "I'm curious (David) about your blurred vision comment, what exactly are you experiencing? It sounds a little different from what most people here are talking about, do you get headaches or nausea as well?"


    Generally, I'm not a person who suffers from Nausea or Headaches, I can probably count the number of times I've taken paracetamol this year on a single hand. I’d certainly be very aware of an increase in either. However I don’t own a problem causing screen at home or in the office, both of which are aging TFTs. My eyesight is excellent. My office is illuminated with T5 fluorescents and a decent volume of daylight and my mobile phone (HTC OneX) doesn’t cause me problems, although the illuminated buttons at the bottom do, I quite often obscure them by holding my thumb over the light. Reading some of the comments on here, this would be considered a ‘pleasant environment’ for some sufferers.

    Working in IT, I use a large range of devices for a very short space of time. Most of the display hardware at my place of work is aging, so the only modern screens I usually encounter are mobile phones, laptops and tablets, but my use of these is limited to short bursts during set up and installation. I would say there are two types of devices that cause me problems, devices where I can tell that the device is ‘bad’ and devices that seem ok, but cause me problems afterwards from as little as 10-20 mins of use, symptoms such as blurred vision. The bad devices are disorientating to look at often forcing me to look away. Samsung seem to be the worst devices for this problem and fortunately I’ve been able to avoid prolonged exposure to these devices.


    To put the ‘blurred vision’ into better words, after using some devices, I experience difficulty focusing on items near me, my screen, paperwork on my desk, I don’t think my distance is effected. My eyes feel fatigued. This effect goes after an hour. This seems worse on devices that appear ok on first inspection, such as newer iPads and the HP ElitePad, most likely because I am not actively avoiding looking at them.


    Hope that helps.

  • CoreLinker Level 1 Level 1 (0 points)

    Just a quick note on the Christmas lights question.


    They do flicker, AND VERY BADLY.


    Since cheap Christmas lights are by default plugged in directly to mains, they flicker at 120 or 100Hz just like a lightbulb would depending on region even if their effects are not controlled by PWM.

  • Jessiah1 Level 1 Level 1 (0 points)

    David, this is very interesting because you are experiencing a different symptom however I would be willing to bet it is caused by LED lights because of your distinct description of the buttons on your phone which are obviously LED back lit. I am curious what happens when you see LED tail lights at night, do they create severe after images in your vision? You would probably do very poorly with an overhead light like this one because it is basically a bunch of really bright lights just like the ones behind your phone buttons. These are not common yet and when they become common more people will have issues because this lighting is so much more sever backlight monitor. Overhead LED.jpg

  • David Turnough Level 1 Level 1 (0 points)

    “I am curious what happens when you see LED tail lights at night, do they create severe after images in your vision?”


    Yes. LED tail lights are horrible. Worst still because they are moving. Moving LEDs or LEDs that move in relation to my eye are very disorientating, they jump around as I blink and leave horrible tracer images, like a sparkler on bonfire night . A simple figure of eight in front of my vision is a good test for devices. With my OneX’s back lit buttons, the figure of leaves behind a distinct tracer. Worst still, my Friend’s Galaxy SIII the whole screen leaves tracer effects, noticeable as he passes me the phone if lets say he’s showing me a video.

  • Eric Leung1 Level 1 Level 1 (5 points)

    With all respect, I disagree with the notion that PWM being the sole cause of eye strain that a lot of us are experiencing in this forum.


    There has been no trace of PWM in all recent Apple devices, and yet, we keep on seeing discomfort reports in this forum. I think that alone is enough reason to believe that there are other causes of the eye discomfort.


    I believe the harsh bright bluish LED is highly related to the "other major cause" of the eye discomfort. I'm pretty sure there's some problem in here, but I couldn't pin point what exactly that is as yet. It could be due to the huge blue spike in the specturm, it could something else.


    However, please understand that this is not a "PWM vs blue spectrum" arguement. They can both exist at the same time! Though, it is apparent that not everyone is affected by both issues.

  • Jessiah1 Level 1 Level 1 (0 points)

    That is very interesting David, there is a group of people who have an issue just like yours especially with taillights and ghost images and tracers. Very concerning when headlights become LED isn't it?

  • Jessiah1 Level 1 Level 1 (0 points)

    I agree with you Eric, I provided this link earlier because even though this coating hasn't fixed my extreme sensitivity I can say with a certainty it helps me for 10-15 minutes, it may help others who are less sensitive completely and is designed specifically for the blue light issue:



    Even if you do not need glasses you could get this coating applied to plain lenses and give it a try.

  • Jessiah1 Level 1 Level 1 (0 points)

    The difference between this coating and others I have tried is that they put science into blocking the specific harmful spectrum of blue light emitted by LED lighting. I have been working with the company and providing feedback to them about this product, I see more coming in the future from them on this front and they are investing real scientific research in this area.

  • Kxtr73 Level 1 Level 1 (0 points)

    My symptoms:


    LG 27' DM2780D LED - after using this one in 5 days with 100% backlight with no flicker and dimmed by graphic card  even more then my CRT screen (dimming by PWM - the same results)

    - feeling hot face when working with it

    - quick both eyes fatigue and strong burning eyes effect

    - display was sufficiently dimmed but always seemed still too bright ...

    - very big pain at morning in right eye (like I was hit by a fist) and congestion of this eye

    - in day 4 and 5 I felt dizzy


    Wearing even sunglasses did not bring improvement.



    Stop using it. 3 continous weeks of: pain, congestion and blurred vision when reading something in right eye and photophobia ....

    Big problems with any artificial light. Problem finally passed away The monitor had in total 24 Watts of Led backlight (info from monitor service manual). There is a lot of light. My kitchen LED has 2,5 Watt and it's enough for washing dishes.



    Acer 24' G245H with two CCFL bulbs - ok.



    Akai 32 TV with 6 CCFL bulbs used as monitor (dimmed like my old CRT) - Unfortunately, burning eyes but not severe



    Generally speaking I don't like too much light (from bulbs, sun etc.) When the sun shines strongly I have often a headache.

  • mvanier Level 1 Level 1 (0 points)

    You know what you experience.  You do not know what other people experience, and it isn't the same as what you experience.  I myself have found that f.lux makes a tremendous positive difference even on CCFL-backlit monitors.  You didn't find this, and thus you conclude that everyone is just like you.  That isn't scientific, or even rational.  Don't speak for others.  If you want to set up a psychophysics lab and do actual research on this topic, go ahead, but don't just make blanket statements in the name of "science".  As far as your statement that since sunlight has all wavelengths (true) and people don't seem to get eyestrain from it (not sure about that, but I'll accept it), and thus there is "no way" that blue light could be the problem, that's nonsense.  White LEDs have a radically different light spectrum than sunlight does.  They have very little red and green components, a lot of yellow (due to the phosphor) and a huge narrow spike in blue.  We have three kinds of color-detecting cells in our retinas (cones): those that are most sensitive to red, to green (roughly) and to blue.  If you can't understand how white LED light could affect eyes differently than sunlight, you're not qualified to speak in the name of science.  Sorry for the harsh tone, but I really can't stand when people say "this is the way it is for me, anyone who says otherwise is just imagining things".  You found that PWM caused your problems; well done!  What if someone told you "PWM doesn't bother me; you must be imagining things!"  That's the kind of thing you just did.  Eyestrain can come from many different factors, and they affect different people to differing extents.

  • mojarvinen Level 1 Level 1 (0 points)

    I understand. I don't want to say that what works/doesn't work for me, is the same for all. But as I said, I've monitored this discussion for a long time and there are a couple things that pop up every now and then, without any real evidence. Like the display driver between Windows 7 and 8. I'm sorry, but I just can't believe that a display driver between different operating systems could cause problems. The problems that people have with the blue ligth from a LED seem also inconclusive. As I said, tried the blue filtering glasses my self. Also, those Uvex glasses can be purchased from Amazon for something like $7. So if there are persons that really think that the Blue light is the problem, buy glasses that filter out blue and test for a coupld of days. Then we would know for sure. I mean, my problem was so severe, that I just needed to find out what helps. That's why I tried several monitors and invested quite a lot of money. I could not work without having found out the PWM problem. So if blue light problem is so severe, I urge people to buy the glasses and try. Then we'd at least know if is the blue light or not.  It is confusing if people with severe eye conditions report probelms in this thread. If you can't deal with normal office lights, then it's likely that you cannot deal with any display for a long period.


    And here the frequency is 60 Hz in the electricity, so Christmas LED's would flicker at 60 Hz which would be visible to most if not all.

  • Jessiah1 Level 1 Level 1 (0 points)

    "And here the frequency is 60 Hz in the electricity, so Christmas LED's would flicker at 60 Hz which would be visible to most if not all."


    This is very interesting, I have read that the Hz needs to be above 75 Hz to be "undetectable". If our power supply is running at 60Hz for everything then it is possible there is a perceivable flicker in everything.

    I personally know for sure through painful testing that flicker is an issue, I also know that 5000K spectrum lighting is an issue for me and probably anything bright white or blue. There is a much greater intensity of vertigo, nausea and migraine for me with anything bright white or blue and I have not found something with that spectrum that does not bother me yet. I feel you both have valid points and I still feel there is a strong possibility both flicker and spectrum are at play here.

  • Jessiah1 Level 1 Level 1 (0 points)

    The UVEX glasses only work for me with fluorecent lighting and this is my personal finding, other people who get random migraines suggested them to me and they fixed my constant migraine issue until LED lighting was installed at my work. The Crizal coating for normal glasses is designed to filter out harmful blue light and it would be the only true test if your having issues with LED. I'm pretty severe but I still have doubts the UVEX glasses would help with LED, just to be clear.

  • Gurm42 Level 1 Level 1 (0 points)



    Saying that you "can't believe that a display driver update" could cause problems isn't helpful. People are seeing REAL problems here, and the fact that you don't understand the mechanism is not helpful.


    There are MULTIPLE issues happening:


    - Blue light

    - Flicker

    - Temporal dithering

    - ???


    To discount any of these is hybristic and unhelpful.


    HOWEVER, now that I've said that - it IS the case that this thread is a bit of a clearinghouse of problems, and it WOULD be helpful to have some consistency in the troubleshooting process!

  • Jessiah1 Level 1 Level 1 (0 points)

    Money being no option we could set up several experiments. We could use a power filter, flicker free monitors, monitors that use PWM and some that don't and some people who are sensitive

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