I've now yet again tested 3 laptops. Matebook X Pro 2020. PWM at some 60 % brightness. Zenbook S U3939, no PWM and Dell XPS 9300. None of these are OK. All cause significant eye strain. Not like PWM, which gets my eyes bloodshot in 30 minutes, but if I use a full workday, my eyes are reddish and watery. Next morning my eyes feel like the lids would be sand paper. So it seems that temporal dithering must be the cause. I've had several laptops over the years which cause no eye strain at all, like Lenovo x280 and some other lenovo's. They all had PWM, but not at 100% brightness, so I was fine if I just set them at full brightness. Same with many phones. OLEDs cause immediata blood shot eyes. I've had many where there is PWM, but only on lower brighness levels, so I just make sure I disable the auto brightness and use them at levels where there is no PWM. But there have been phones with no PWM, Like some Huawei's and Xiaomi's which still have caused severe eye strain. But those have had better color reproduction, so I suppose this means FRC or temporal dithering. Now I'm thinking of getting a native 10bit desktop display to confirm that temporal dithering or FRC is the problem. My thinking is that it is the pixel flickering that is my issue among PWM flickering and then if a display is native 10 bit, there would not be any pixel flickering like temporal dithering. Would anyone who is more knowledgeable in these, care to comment if this might make sense? For me it is not Windows version or driver related, since those laptops and desktop monitors that don't cause eye strain, I have always used the newest Windows versions and drivers. Then of course, if there happens to be a laptop with 10bit screen, I would be interested to try it, almost no matter the cost of it, since really, I need to have a laptop due to my work, but now it starts to look like there simply are no new ones. I may have to start hoarding old Lenovo's with poor displays to be future proof for a few years. But what then - some day those will just be too old and I need to get a laptop with the modern display tech, which I simply cannot use. Well, I can, I don't get migraines, but it is really irritating to have bloodshot eyes constantly and use eye drops to compensate the dryness, the dryness which is only caused by the flicker. And anyway, there are number of forums discussing this problem. How can it be that we make no progress?

I would also like to understand why some Android phones are completely OK, not causing any eye strain and some are not. With phones it seems to be PWM related, so that if there is a PWM, it is OK when used in the brightness level where there is no PWM. But all Phones that I have tried, that do not have PWM, will cause eye strain. How come there is nobody from the actual display industry participating in these discussions. There must be someone who has this problem and knows the actual technology. There are so many places around the net where people are discussing this that it is clear that this problem is not that rare anymore. Though I see one of the problems being the fact that many of these discussions end up discussing food supplements or other health issues, giving outsiders the impression that it is a vague issue that comes and goes and would have some placebo components in it. For me it is totally binary without anything circumstancial or vague. If there is flickering in a display, it irritates, if not, it does not irritate. I also find it a bit annoying that sites like Notebookcheck keep pressing the disinformation that frequencies over 500 hz would not cause a problem. I've had several phones with a PWM of some 2500 Hz and it is without doubt irritating my eyes. If I use the phones with brightness level where there is no PWM, I will have zero irritation even if I would use the screen for 12h a day. My optic nerves are able to sense a flicker of 2500Hz. I could show this in a blind test any day easily as people would be able to observe my eyes turning bloodshot by the 2500Hz flicker.

Maxx How come there is nobody from the actual display industry participating in these discussions. There must be someone who has this problem and knows the actual technology. We had a Microsoft employee (that someone tried to bring here to investigate alleged Windows 10 display issues and a few other things), but he seems to have gotten lost as COVID got worse. Maxx I also find it a bit annoying that sites like Notebookcheck keep pressing the disinformation that frequencies over 500 hz would not cause a problem I do agree that generalized statements like that are harmful. The closest to empirical data I've seen here was an old "lighting industry" paper that claimed certain "strobe" effects rapidly dropped off after a few KHz. Again old paper, and I'm not sure of the methodology used.

It would be nice to meet a person with similar situation than mine. Most of the time people seem to have all kinds of other issues which kinda obscures the situation. I've had the PWM sensitivity for more than 25 yeas, so most likely since birth, or at least since puberty. I don't have any other health issues or any other rare issues. It is just the flicker that causes my eyes to go red. Though related item is that my eyes turn bloodshot by even moderate alcohol use. This of course happens to many others, but my case my eyes get so red even after a few beers that people start commenting my red eyes. So my eyes do get red easily, but with a flicker free monitor I have zero problems no matter how much I use the monitor.

Has anyone had any success with g-sync or freesync laptops?

Maxx I think g-sync in the case of laptops means the screen has no PWM by default, but a) those are often "bulky" gaming laptops, and b) "Other" software issues can still come into play.

Maxx of the time people seem to have all kinds of other issues which kinda obscures the situation I think part of the issue is you get triggered by one source (PWM), then if you don't improve your situation, your condition gets worse over time.

@JTL Disagree totally. Like I wrote, I've had this for more than 25 years and particulary some 15 years ago, when I had no idea what was causing it, except for that the cause is a computer monitor, I was using PWM monitors constantly and my eyes were constantly bloodshot and very irritated, but once I learned about PWM and was able to get a PWM free monitor, the problem disappeared completely. It is just in recent years that manufactureres have started to utilize the FRC/Temporal dithering with many screens that also cause flicker, this problem has come back. But always when I find a device without Temporal Dithering and use it with brightness levels where there is no PWM, the problem disappears. The thing is that it does not seem to be possible to eliminate the flicker anymore with most devices. Even if there is no PWM, there is Temporal dithering and there is no way to remove that. Programs like Ditherig or Iris do not help at all.

There is nothing mystical abou this problem. It is very much like excercising muscles. If you excercise too much, your muscles will get sore, but when you stop it, they will heal. Similarly, as the optic nerve senses the flicker it will get strained and strain the muscles in the eye, which cause the bloodshot eyes, but when you stop doing what causes it, then the muscles / nerves heal.

I think the issue is that not everyone is affected by PWM, Muscle strain wouldnt be immediate, a 'bad' screen device will affect me almost immediately I have a CCFL monitor that has PWM and I used it for 11ish years with no problems, I didnt know what PWM was! I had an OLED samsung S6 phone, had PWM was fine untill I dropped it 🙁 Then I got other devices with PWM and they were not fine, then I got other devices that dont have PWM and they were not fine, I've returned motorola phones with and without pwm and laptops without PWM but they still caused problems The only consistent thing for me is that devices that are using technology up to around -2018 are OK, newer items are NOT ok for me. - my newest OK device is an Ipad from 2018 but I have to use reduce white point. There are some exceptions though but I think this is firmware related OR I have irreversably damaged myself Anyway - how can we tell if we have a 10 bit screen? I would also like to hoard old lenvo machines as I've had success with them although one died on me recently.

I have now tested 5 laptops in a few weeks: Matebook X Pro 2020 - LCD pwm at 60%, used at higher brightness but still caused some eye strain after several hours of use, not usable for work purposes as it would require daily 10 h usage. Asus Zenbook UX393 - LCD without PWM, but causing much more eye strain than Matebook, probably Temporal dithering? Dell XPS 9300 - LCD with PWM at 25%, but used at higher brightness, similar to one above, might be a bit less eye strain, but still difficult for work usage Lenovo Legion 5 Pro - LCD witout PWM, Nvidia 3060 discrete, 165Hz refresh rate. Seems to not cause eye strain, at least not that bad. I have to try it a couple of more days at work. Suspected cause of not causing eye strain is Nvidia discrete graphics and 165 Hz refresh rate. Asus Zenbook Flip U371 - OLED with PWM below 52 %, 60 Hz slight lowring of brightness above 52%, similar to PWM, but does not seem to cause major eye strain. I will still keep testing.. Suspected reason of not causing eye strain: 10bit OLED without FRC / Temporal dithering and lack of actual PWM above 52%. The slight eye strain that seem to feel might be due to the 60Hz slight banding above 52%, but will it be a problem after using 10h on consecutive days, remains to be seen. @HAL9000 there are very few actual 10bit screens in the market, none for laptops that I know of. Mostly high end photo editing screens. I was also able to use CCFL screens with PWM (at least some of those) with minor eye strain. That is because CCFL dims and lights up slowly, so the flicker is not as abrubpt as with LED and OLED. I personally think that the newer devices are problematic as manufacturers are squeezing more colors out of lower quality panels with Temporal dithring / FRC. Now why this does not seem to be the case with the Lenovo Nvidia combo is that I disabled the integrated GPU from the bios and use only Nvidia GPU, which might have different type of dithering or no dithering at all. But who knows. The problem with the non PWM screens causing eye strain is that the eye strain is not immediat like with PWM. it requires several hours of usage. So often times I might think that the screen is OK, but after the second workday where I've used the screen for 8 h or so, I see my eyes being bloodshot. This is similar to CCFL PWM. if ai was gaming every night for several hours, my eyes started to get strained and bloodshot in a couple of days. This does not happen with my HP ZR40w27 display that does not have PWM. (some 8 years old) or e.g. with Surface Pro 2 at full brighness. Or with Sony televisions without PWM. Even if I would have strained eyes from PWM, I can rest my eyes using the HP display or a sony TV.

Laptop for those with PWM and flickering sensitivity

Maxx

@HAL9000

You have an interesting situation with the problems starting on previously found OK devices.

I have not experienced anything like that during the 25 years I've had this.

I also have had no success in getting a device to be OK by disabling dithering with ditherig.exe or anything else. No matter if I use polarized sunglasses, blue blocking glasses or computer glasses or no glasses or a glass of milk.

If there is PWM it is always bad, less bad with CCFL.

As for the temporal dithering or FRC, I've not yet been able to fully confirm. On a previous job I used a HP laptop that did not have PWM, but had the temporal dithering type of eye strain and when I connected that laptop to an external display, I was fine.

So for me it is kinda straight forward. Most new devices with great screens, even without PMW will cause bloodshot eyes. In that sense it is even more straight forward (or should be e.g. for doctors) as they can actually verify my bloodshot eyes. For persons with migraines it can be more difficult ans migraine is difficult to verify and is oftentimes thought to be associated with stress. This must make it more frustrating, as e.g. for me, migraine is not associated with stess, but a couple of times people have inferred that is is related to stress, though it is completely and absolutely random. I can get it on a long holiday while relaxing by the lake, or sitting in an aeroplane or sleeping.

But the red eyes are quite a physically verifyable symptom, but still all doctors try to infer that it is something psychological, while clearly it is not. Or then I have some phychological super powers as my eyes will turn red in 30 min with a display that has PWM at 99% but not 100%. My magic psychological powers are able to sense the 1% difference in brighness and absolutely without fail turn my eyes bloodshot in 30 min 😉

HAL9000

Maxx

I think the issue I have with some software, such as games is if they update the game engine or whatever or change the way colors are presented / flicker etc is what gets me. I want to be able to try things with a 144hz screen but at 75hz still an issue. There are some games that I've played and refunded that trigger my symptoms immediately so I believe its also related to game engines etc again.

I get what you mean though, it can be very stressful to be told you're stressed when you're not!

The PWM / eye bloodshot is easy to proove as you say. Think of a strobe light when describing it, think what your iris is doing, opening and closing rapidly as the light flickers and this with slight eye movment causes the muscle pain around the eyes.

Maybe with flicker at 1000+hz some people have eyes that still react in such a way thus making the eyes tired and red, then people like me also get migraines from it - but again I still dont think these are migraines / they are a different sort of migraine.

I'm 3 or 4 days into one now, its levelling off. I have a Lenovo t440 on the way that should have a TN screen so I have some hope that my migraine is totally gone soon and this new old laptop will be ok

weasley

@Maxx I've always had Lenovo laptops and I love them overall.
But since eye-fatique is getting worse i'm more dedicated to find a solution.

The feedback you give on Lenovo Legion 5 Pro does give me a spark of hope, since I'm really interested in this laptop.
And i'm glad you can disable igpu in the bios, I didn't think this was possible.
Do you have any instructions?

Maxx

weasley I'm still testing the lenovo today and tomorrow before I decide if it is OK Or not. Yesterday I concluded that the Asus with the OLED would be ok to use a few hours a day, but now waking up I do have a bit irritated eyes from using it yesterday some 8h.

I still have to test the Lenovo similarly today to be sure is it better or not

The igpu disabling does not require any instructions. Just hit f2 to enter bios and select from a dropdown. Actually, I think it was disabled by default.

Maxx

I have clear evidence that my eyes get red with PWM of 2400Hz. I had Sony Xperia phone that had 2400 Hz PWM at 33 brightness. When ever I let auto brightness lower it or manually lowered it, my eyes got red. Finally I just kept it manually over 33 and I had zero problems with it for the 2,5 years that I had it.

I know it sounds unbelievable and sites like notebookcheck also kinda claim that it is not possible to sense such high frequencies, but my eyes do without a doubt. Anyone could verify this by seeing my red eyes.
If the ears sense 20Khz why would the optic nerve be able to sense 2,5Khz? I dont claim that I see the flicker, the flicker just makes my eyes bloodshot.

JTL

Maxx I have clear evidence that my eyes get red with PWM of 2400Hz. I had Sony Xperia phone that had 2400 Hz PWM at 33 brightness. When ever I let auto brightness lower it or manually lowered it, my eyes got red. Finally I just kept it manually over 33 and I had zero problems with it for the 2,5 years that I had it.

I once read a paper from the "lighting industry" that claim that some of the effects of PWM persist up to around 10KHz, but I'm not entirely sure of the methodology involved.

HAL9000

I dont mean to hijack this thred but I've recieved my Lenovo T440, intel 4300u HD4600 - although even after updating the drivers its reported as 'intel HD graphics family' - I know its not a new machine and used is hit and miss.

Either way as I suspected / hoped this machine is totally fine for me to use - it doesnt appear to have PWM but as it was used it is not in amazing condition but refurbished to a high standard and around 1/3 the price of the HP envy that I returned recently.

Its got a HD TN screen that is very poor even for a TN and very dim - but this is good for me. I actually have 2 other IPS screens that should fit so I can experiment with that.

Hoarding old Lenovos appears to be the way forward at least for me. Annoyingly I can buy the same machine again for cheaper now but I'll hold off I think.

I do agree with the comments on Notebookcheck, sometimes they're wrong as well and devices they test have PWM - but this may be regional / panel differences, but yes I do believe some people, myself included can detect and be affected by very high frequency flicker / PWM.

Maxx

HAL9000 Yes it would be interesting to know what is it that makes an older Lenovo TN or IPS good for us, but newer with better color screens are not. PWM is an issue for me in those Lenovos also, so I have to keep the brightness at 100% as not to have the PWM enabled.

Maxx

just a status update. I had to return the Lenovo Legion 5 Pro. I was able to used it a full workday, but in the afternoon my eyes started to feel strained and then the whole evening my eyes were irritated and dry. Not that badly bloodshot as with a PWM screen, but clearly there is some flicker in that screen, maybe from temporal dithering.

Again, I could rest my eyes with the HP desktop monitor or a Sony TV after using the laptop for a day. So it is not my eyes per se, it is the bad display.

Lauda89

Maxx So at the end, what do you keep? The Asus notebook with OLED screen?

Maxx

I'm still testing the Asus Oled. Not sure yet, as I've not had a chance to used it like I would on a typical workday. But I'm pretty sure it is better than the LCD screens. I use it over 52 brightness where there is only a minor dip in the brightness at 60Hz.

I was able to use Galaxy S2 6 years ago without problems, it was and has been practically the Only Oled phone without PWM.

jen

JTL I once read a paper from the "lighting industry" that claim that some of the effects of PWM persist up to around 10KHz, but I'm not entirely sure of the methodology involved.

This may have been a reference to this 2011 paper by Bullough et al. where 20% of people could still notice the stroboscopic effect of flicker at 10,000Hz. They did not test higher frequencies, so did not determine at what frequency no one can detect flicker. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.876.126&rep=rep1&type=pdf

Maxx

So, the Asus Oled is going back as well.

After using it a full day and also in the evening, my eyes are quite irritated today.

After testing 5 laptops from different manufactures, Intel / AMD. LCD/Oled, there just is not a modern laptop that I could use.
I probably could survive with the OLED, ensuring its above 52% brightness. But I would need to limit my daily usage to a few hours. Only time would tell how much I could use it on a daily basis. But then again, there will be long workdays when I need to watch the screen for 10-12h, so I need a laptop that will not irritate my eyes.

Now I'm "resting" my eyes with this HP desktop monitor for today and maybe I'll try a couple of days more, but it is clear that the OLED is also straining my eyes.

Some people would say that of course your eyes get tired after watching a screen for 10 h. No, they will not get tired watching this HP desktop monitor or an older Lenovo with poor screen. They will also not get tired watching a Sony LCD TV without PWM. Nor reading a book even in situations when I have a real page turner and read it during the day and most of the night.

So the problem really is in the screens, not my eyes. Yes, my eyes might be more sensitive than most people, but manufactururers should still be able to make screens that do not irritate the eyes.

I've heard this countless times from people who are oblivious to this problem that their eyes get tired or they get a migraine after a long workday. It IS the flickering in the screens that is causin the issue, it is not their eyes or their migraine. They would not have the problem with a screen that does not flicker.

It is also not blue light. The blue light hype is the most outrageous marketing bs that is going around nowadays. These Eye Care moninors that supposedly emit less blue light. People's eyes do not get strained outdoors on a clear sky day, thought the amount of blue light is massive in comparison to any screen available. Blue light does not irritate eyes. Flicker does.

JTL

Maxx People's eyes do not get strained outdoors on a clear sky day, thought the amount of blue light is massive in comparison to any screen available. Blue light does not irritate eyes. Flicker does.

I think the issue there isn't with "blue light" per se, but the fact that the blue spectrum dwarfs all the other spectrum

@TechSensitive did an article some time ago measuring the spectrum of various other "lights" (sunlight, quantum dot backlit LCD, etc.)

https://techsensitive.com/how-sunlight-is-different-from-leds-and-other-lights/

Can really see the difference between the two plots...

Maxx One thing I would like to confirm is to get a 10 bit desktop monitor without PWM, to see if the lack of temporal dithering would show that it really is the 8 bit + 2 bit FRC that causes the issue. I'm pretty sure it is. In my case the drivers or the other hardware does not have any affect. It is the actual display panel tech that is causing the issue, since no matter what hardware and software I have with the HP desktop monitor, it will not irritate my eyes

Some dithering is done by the GPU itself, and some GPUs can be rather obnoxious about it (speaking from experience). I have my own video capture solution that can detect it in (most of) those cases.

Maxx

The vendors have had so many claims about irritaeted eyes, that they have come up with the marketing idea that it is blue light that is the problem, as they are not able to manaufacture screens that would have 100% RGB coverage and would not have temporal dithering.

One thing I would like to confirm is to get a 10 bit desktop monitor without PWM, to see if the lack of temporal dithering would show that it really is the 8 bit + 2 bit FRC that causes the issue. I'm pretty sure it is. In my case the drivers or the other hardware does not have any affect. It is the actual display panel tech that is causing the issue, since no matter what hardware and software I have with the HP desktop monitor, it will not irritate my eyes. Also if I connect a laptop that irritates my eyes to this HP desktop monitor, it will not irritate my eyes, but the laptop panel will.

Maxx

Yes, this is clear, the spectrum favors blue light. But the blue light from a screen is 1 and the blue light from the blue sky is 100 or more. So even if the spectrum favors blue, I don't buy the idea that it would irritate the eyes.

Macular degeneration or some other very long term eye problems could arise from staring a blue light 10h a day, I think there is some science behind that, but I have not seen any science that looking at a non flickering blue light would irritate the eyes.

In the article suns spectrum is measured most likely by taking direct sunlight. But what is the spectrum if they would measure only the light that reflects back from the blue sky?

Or what if a person is in a room painted blue lit by blue light. I don't think there would be any eye strain

So I do understand thei point with the blue light but my opinion is that it is just hype generated by marketing people, I have not seen any scientific studies showing that the blue light from a non flickering light source would irritate the eyes.

I think that in most cases they have just mixed flicker with blue light as the flicker is something (temporal dithering) that cannot be measure.

Could you detail your rig how you video temporal ditering?

JTL

Maxx Yes, this is clear, the spectrum favors blue light. But the blue light from a screen is 1 and the blue light from the blue sky is 100 or more. So even if the spectrum favors blue, I don't buy the idea that it would irritate the eyes.

I've personally seen flicker free blue LEDs on certain electronics of bright intensity, and it's not very pleasant to look at.

I don't buy that even in the case of a flicker-free display with no dithering that "everything is entirely fine, move along", hence the drive for more research.

Or what if a person is in a room painted blue lit by blue light. I don't think there would be any eye strain

I mean, this kind of brings back an earlier point of mine. CRT monitors had a more even spectrum compared to "modern" WLED backlights, and I don't recall people obsessing over color temperatures with those.

I think that in most cases they have just mixed flicker with blue light as the flicker is something (temporal dithering) that cannot be [measured].

Could you detail your rig how you video temporal ditering?

There are still many unknowns with the dithering problem, one being that the display outputs on a laptop versus the connection used for the internal LCD do differ, so it's not trivial to reliably detect dithering on a laptop as using the internal LCD.

I haven't written up all my notes and testing, but here's some info on my project "VideoDiff"

https://ledstrain.org/d/848-project-videodiff
https://wiki.ledstrain.org/docs/appendix/tests/dithering/

Maxx

@JTL Yes, I agree that staring at a blue light for hours every day might not be good for eye or sleep health. So I agree that the lightspectrum should be as close to natural sunlight as possible.

But does the blue light spike in the spectrum actually cause any significant eye strain? Not at least for me and presumably to most people, since most people do not experience any eye strain from any screen, even with PWM or Temporal Dithering.

So that's why I argue that the marketing BS about blue light is misleading as it tries to connect blue light to eye strain, while most people do not experience any eye strain with screens. Those who do, the cause is most of the time PWM or dithering.

Maxx

I was thinking if the dithering could be detected by purchasing a cheap microscope and filming that with a dlsr or even mobile phone.

Phip

hi, i use the razer studio 2020, with the quadro 5000, older driver, but the screen is pwm free, one of the very few. maybe test it as it works for me really well.

Quad43

Phip which drivers?

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