Hi!
I am translating my story that was initially written here. It is both my intro and also a description of a problem that does not seem to be discussed in English, yet. I called it Problem X, simply because I had no slightest idea what causes it for a long time and now I only have a hypothesis. It is very hard to pinpoint. There are similar stories in that thread, but it seems I am affected stronger than most.
I wrote my story and the tests I made in the tiniest details so that it can help with any further research if needed.

Key features of Problem X:

  • inability to adjust the brightness: the screen is either completely dark or immediately too bright
  • white color on the screen is blinding. White text on a black background is blurry (more blurry than usual for people with astigmatism)
  • a subjective feeling of looking at welding
  • severe pain and pressure in the eyes, subsequent trouble focusing into the distance (not a specific symptom as it may be present with other problems)

My previous tech

Previous phones:
Samsung Note II - Super Amoled screen, PWM
Samsung Note 3 - Super Amoled screen, PWM
Samsung Note 5 - Super Amoled screen, PWM (PWM 240 Hz according to these measurements)
The Samsung Note 10 Lite was the first phone where I encountered Problem X; used it for 3 weeks and switched back to Samsung Note 5.
Samsung S20 FE is the current phone, I have been using it (or better to say have been avoiding using it) since the beginning of October, with some hope to find a solution.

Phone usage - many hours a day. The phone is the device I spend the most screen time on. On Samsung Note 5, I could read for several days in a row without a break, without even feeling tired.
I always immediately set up my tech for myself, to make it comfortable for me. I prefer matte screens, a warm white color temperature.
I feel comfortable with low brightness, all phones and screens are used by 10-30%, no more.

I had no previous troubles or complaints with any kind of tech, apart from two minor things about 10 years ago.

My vision

Feels perfect, the picture is absolutely clear. I have slight astigmatism (1.75) in one of my eyes, which I don't feel when I look with both eyes. Thus, I see the horizontal lines with that eye absolutely clearly, and the vertical ones are slightly blurred.
I don't need glasses or correction.
I have never had vision problems. I don't have photophobia. I walk under the summer sun without sunglasses, I don't like them.
My eyes instantly focus at any distance.

When I had my light sensitivity symptoms at their strongest, I went to a full ophthalmological examination.
It included:

  • standard visual acuity test with a refractometer
  • checking peripheral vision with a device
  • measurement of intraocular pressure
  • analysis of the nerve fiber of the retina and the head of the optic nerve, analysis of the macula with the device
  • computed tomography
  • examination of the fundus under a microscope
  • eye moisture test
    (There were a lot of tests, hope I made no mistakes in this list)

Everything was absolutely fine with me, my eyes were completely healthy except for astigmatism. Nothing more interesting was found, although they tried.

Does astigmatism affect the phone problem?
It may be more difficult for me to focus on a dangerous screen with an eye with astigmatism. In the beginning, it was the first to start to hurt, it hurt longer and stronger. But without this screen, I do not feel any problems with the eye. Later both eyes were suffering evenly. This same eye is the dominant eye (the one on which the individual primarily relies to obtain accurate spatial data).

Samsung Note 10 lite

In spring 2021, I decided to change my smartphone, from Samsung Note 5 to Samsung Note 10 lite. In the store, I had no questions about the screen. At home, it began to seem to me that it was not very comfortable to look at the screen - as if there was something wrong with the brightness, and the image clarity was poor, and something was... not right. I decided that the matter was in the factory settings and began to habitually change the font-color temperature-etc. The situation did not improve with any new setups. I noticed a strange thing: the white font on a black background was blurry. I didn't have this on other phones.
The next day, I started reading with the usual low brightness, and I noticed a strange new thing: the text seemed fuzzy, it was kind of hard to focus. When the brightness was increased, it became too bright for the eyes, but the text became clearer. I did not find a comfortable brightness.
During the first two days, I felt a weird pressure in the eyes. I don't remember at what point. The pressure on my eyes increased, I began to actively set up the phone and tried different software settings.
Then I tried, just in case, to remove PWM with the Oled saver and found out that it did not help my eyes in any way.
For the first few days, I did not realize the importance of the symptoms and thought that I would either get used to it or find a solution. Meanwhile, the pressure in the eyes was building up, and after using the phone, it became difficult to see clearly into the distance. When looking into the distance, I also felt pressure in the eyes. The pressure of a similar force in the eyes is felt when you try to look at the bridge of your nose, or look at stereo images, crossing your eyes. But the direction of pressure felt different. The pressure started the second I looked at the phone, then built up.
I realized it was bad. I checked if the matrix is ​​defective - no, it is no different from other note 10 lite in the store, they also had the same effect on me. I checked if a particular model was to blame - no, the entire Note 10 and Note 20 model line was terrible, maybe a little weaker than the Note 10 Lite.
I continued to use my phone and the pressure turned into a sharp pain the moment I looked at the screen.
In the second week, the spasm became persistent, it did not go away if the phone was not used, and to maintain the persistence of the spasm, it was enough to look at the phone for a few seconds a day. I could not see clearly at medium and far distances, my eyes were pressed and hurt when trying to focus far.
For a long time I searched for similar symptoms and a solution on the Internet, I did not find anything useful. After making sure that PWM was not to blame, I gave up, sold the phone, and returned to Note 5. In total, I used Note 10 lite for 3 weeks. In another 2 or 3 weeks after returning to Note 5, my eyes returned to normal, my vision was completely restored and I completely forgot about the problem.

Phone selection

In September, I broke my Note 5 and I made a second attempt to update the phone.
I started by walking into every retail store and looking at their entire phone range with my eyes. The original plan was to find a set of models that wouldn't hurt my eyes and then choose between them.
It turned out that there were no such phones.

Phones I have tested:
Absolutely everything that was in Ukrainian retail stores as of September 2021 and cost above $270. Gave special attention to IPS phones and AMOLED phones flickering at 450 Hz+
Including:

  • iPhone 11
  • xiaomi 10t pro

For a mysterious reason, I was most comfortable on 3 models: Xiaomi MI 11 Lite in the first place, Samsung S20 FE in the second, Iphone 11 in the third.
By "most comfortable" I mean that the phones hit me in the eye not after 5 seconds, but after 15.
At first glance, it may seem that these three phones are united by the topic of dimming: Xiaomi MI 11 Lite has a very unusual flickering scheme, Samsung S20 FE has dc dimming, Iphone 11 has ips. However, Xiaomi IPS models and high-frequency PWM phones hurt my eyes instntly on par with the rest, as did the Iphone 11 unless lowering the white point in the settings.

I have noticed that the reflective properties of modern screens, or rather their glasses, have increased: most of them are glossier and more reflective than my Note 5. The reflection of a ceiling lamp on a modern screen (turned off) hits the eyes more than the reflection on the Note 5 screen. To eliminate glare, I pasted a matte film on the screens in the store and realized that the film improves something.

I decided to experiment with S20 FE.

Samsung S20FE

Since purchasing the S20 FE, I've experienced a wide variety of symptoms. When screen protectors were applied on the phone, the symptoms vary. When I peeled off all the layers, the symptoms approached the Note 10 Lite, but were somewhat easier.
What I felt with films or glasses above the screen (simultaneously or alternately):

  • sharp pain when looking at the screen
  • pressure when looking at the screen
  • pain when looking into the distance
  • pressure when looking into the distance
  • unable to focus into the distance
  • difficulty to focus at medium distance
  • double vision of small objects at a medium distance
  • slow focusing when looking from the phone to another object
  • the picture in the camera app looked strange, distorted, "curved", sometimes a little stereoscopic
  • once or twice the movie on the screen looked a little stereoscopic: the silhouettes of the actors were as if cut out of cardboard and were close instead of being two-dimensional and far away
  • eyes perceive the screen as too bright, but the picture does not look particularly bright
  • when the brightness decreases, the first few seconds it becomes easier, and then, when the eyes adapt to the decreased brightness, it starts to burn again
  • feeling like I'm looking on a wielding
  • the screen seems to be the brightest object in the room
  • eyes burn, as from a burn
  • eyes becoming very red
  • watery eyes
  • eyes dry up, there is a feeling of sand
  • difficult to focus. I want to squint all the time to improve clarity
  • I look as if at the screen, but on a comfortable phone I look as if through the screen, without peering into the letters
  • eyes seem to twist, trying to peer
  • something clicked in my eyes. I did not know that there is something to click in the eyes - but there is, it turns out.
  • photophobia: light bulbs seem too bright
  • the colors of ordinary objects looked neon: for example, red appeared orange. This did not happen at the time of using the phone, but, for example, the next day
  • prints of ordinary light objects, such as windows, began to remain brighter and longer on the retina
  • the screen of the comfortable phone resembles a white sheet: the light seems to remain in it and does not go beyond the glass. The screen of the S20 FE resembles a LED lamp with harsh light as if the light is directed into the eyes.
  • the image of the phone is sharply imprinted on the retina if you take your eyes off it. I don’t remember such a strong effect on another technique.

Later on, at some point in time, I had to use S20 FE for a few hours per day for a couple of weeks. It added to this list of symptoms:

  • horrible light sensitivity, inability to walk on the street with cloudy weather (had to wear sunglasses)
  • pain from light sources being somewhere in my vision field
  • red blood vessels appearing on my eyes after a second or two of looking on the screen (checked with mirror)
  • after the end of these two weeks I started to see my own blood vessels in my vision field when I am very close to a light source. I see them every time when I walk under lamps in my apartment.
    Light sensitivity did not resemble migraine light sensitivity in any way (I can compare), it was something else, felt traumatic, maybe dry eye-like. Pain from light sources felt different than my other behind-the-eyes pain, I suspect it was on the surface, probably connected to visible blood vessels.

I didn't experience any neurological symptoms. No headaches, no fatigue, no brain for - only vision problems.
All of these symptoms came and went, depending on the combination of screen protectors and time on the phone.

Then I significantly decreased my phone usage to a couple of minutes per day. But I made a mistake and tried to switch to another phone, an old Redmi 4a. I had a number of layers above S20 FE that successfully limited this pressure feeling, and I got it full-scale from Redmi 4a. I am now avoiding both phones, but unfortunately, Redmi 4a added to my list of symptoms:

  • I felt strong pain and inability to move my eyes at all, for about 4-5 days, starting from the next day I tried Redmi 4a (I had to look in front of myself and avoid slightest eye movements or focusing)
  • I feel tired from my safe notebook or other screens and just from looking at anything close
  • I feel constant subtle pressure behind my eyes
  • Double vision persists

Now, this continuous pressure feeling eventually led to a couple of headaches in the middle of usage of my safe screen. When I checked my vision in the middle of a headache with the Brock sting, I found out my focal point was jumping like crazy. I lovered the brightness of my safe screen beyond minimal using Dimmer, and it seemed to prevent any further headaches.

Is there a picture that is particularly painful to look at?
Yes.

  • a white charging indicator on a black AOD, which is displayed with increased brightness. It's like a knife is stuck in the eye.
  • scroll, at any screen refresh rate. Scroll through the page or something on the screen - and immediately a sharp pain. To feel discomfort, it is not necessary to peer at the screen or read the text. If a person scrolls this screen more than half a meter away and I don't see the text, I'll still be hurt.

Experiments and hypotheses

At the very beginning, when I purchased S20 FE, I felt an immediate pain/pressure when I looked at its screen. It stopped the second when I turned it off. I had zero reaction to anything else, and I was a walking bad screen detector. I used that to make a plethora of experiments. I made the same experiment a few times to ensure that the result is correct.

What do the percentages mean in the text?
These are percentages on a scale of suffering from 0 to 100%.
I replaced the description of subjective sensations with them, so as not to write "helped quite a bit", "helped a little", "helped a lot".
For 100%, I took the key symptoms of using the Samsung Galaxy 20FE: things further from me becoming blurry, double vision, inability to focus into the distance; focusing on near objects takes from 10 seconds to several hours; pain or pressure in the eyes when looking at the phone, pain or pressure in the eyes when looking at everything else after the phone, a feeling of excessive screen brightness.
After each experiment, there is a subjective percentage of how much easier it became to use the phone.
To use the Samsung Galaxy 20FE, I need something that will help at least 95%. I can't use the phone without a solution that helps 95-100%, the phone is dangerous to the eyes. Literally.

Settings for the experiments:
color profile "Natural colors"
brightness 10-30%, at which PWM is visible on the pencil test. To double-check, I rechecked some of the experiments with the Oled saver turned on, without a PWM on a pencil test. Auto brightness is off.
power-saving mode enabled (because it dims the screen brightness a bit)
refresh rate 60 (because I can't change screen frequency with power-saving turned on)

So, I tested all the things that came to my mind, however unlikely they might be, to find some clues. Here are these things:

software settings

  • on Note 10 lite, the first thing I did was set the font size, white color temperature, brightness, screen resolution so that they visually matched with the picture on my favorite Note 5. I literally put them side by side and set up the most similar picture. - Did not help

Settings on S20 FE:

  • bold font, contrast font, enlarged font, enlarged screen scale - did not help
  • built-in blue filter - did not help
  • black theme - did not help
  • Lower screen resolution - didn't help
  • screen refresh rate 60 or 120 - felt a little different, but did not help
  • low brightness - did not help, brightness below the minimum system (using black filters) - did not help. However, when the phone dims before the screen turns off, it's easier to watch.
  • reduce the contrast with a filter (by overlaying a gray filter that makes black lighter, white darker) - did not help
  • color profile "saturated colors" instead of "natural" - worsened
  • reduce the brightness of white with black filters - helped by 5%. I went through a number of programs that lower the brightness by applying a black filter, and of them only one (Screen Filter) gave relief to my eyes. Apparently, the filters are slightly different from each other. Try several filters to find the one for your particular screen. By the way, Android 12 will have a built-in black filter.

Screen gamma may contribute to the problem; the first thing that may somehow improve the situation is to reduce the brightness of white, the brightness of light colors, reduce the overall saturation, contrast. Unfortunately, on mobile operating systems there is no way to adjust the gamma. Now it's impossible even under root. Only on older phones on some custom firmware.
An important exception: in iOS, you can reduce the brightness of whites and highlights without reducing the brightness of other areas of the picture. That is, reduce the brightness of the white point. Customizable in Accessibility. I recommend that iPhone owners try it - it should help at least 10-15%.

sinister PWM

Here are some guides about how to check if PWM is the problem. It is not enough to find out that PWM is present, there should be a correlation between PWM and symptoms.
It is necessary to check the PWM on a bright image. On dark, and moreover black, there may be no detectable PWM.

  • oled saver does not remove eye pain. It doesn't even make it easier. Paradox: oled saver makes the pain worse. Did not help
  • several other filters that remove the PWM did not help
  • using the phone at 100% brightness - did not help (plus the brightness burns out the eyes even on a bright sunny day)
  • the pencil test shows that on the S20 FE, starting from 30% brightness, the PWM becomes invisible with the pencil. Using the phone at a brightness above 30% - did not help
  • I tested IPS phones including iPhone 11, Mi10 pro, and Amoled phones at high frequency. Did not help
  • Against the PWM theory is the fact that for the last 10 years I have been using Samsung flagships with Super Amoled displays, each of which had a PWM, most likely a low-frequency one. Note 5 flicker and Note 10 lite flicker looks exactly the same on camera, but the Note 5 is very comfortable for me, and the Note 10 lite is the worst of them all.

infrared light

  • the infrared sensor on S20 FE seems to be at the bottom of the screen. I closed the entire bottom of the screen - it did not help
  • infrared light does not pass through water (at least google says so). I poured one and a half cm of water into a transparent glass bowl and looked through the water - it helped by 10%. Conclusion: infrared light has nothing to do with it (otherwise the symptoms would disappear), but for some reason the water itself helps

ultraviolet light

  • ordinary glass - did not help
  • used professional glasses BactoSfera UV BLOCK (protection from the entire spectrum of UV). They have 2 pairs of very dark lenses at once. By darkening the picture, the screen was easier to look at, but just as difficult to focus on it. When the brightness of the phone was increased, the eyes began to burn again. As the barrier helped by 25%, as UV protection did not help (because the symptoms did not disappear)

blue light

  • turned on the built-in blue filter to the maximum - it did not help
  • downloaded a couple of other blue filters - did not help
  • displayed rgb(255, 0, 0), rgb(0, 255, 0), rgb(0, 0, 255) in turn. Pure blue is harder to look at. This is to be expected, since blue light has such a feature that visual acuity decreases when interacting with it. But, most importantly, pure red and pure green are also painful to look at. Did not help
  • set background in FBReader rgb(some value, some value, 0) to exclude blue pixel. Did not help
  • I took anti-blue glasses in optics. I was shown how they block out blue light with a blue flashlight. I looked through the same glasses at the phone - it did not help

glare on a glossy screen

  • covered with a matte hydrogel film. Helped by 3%. Most likely, the film helped not from glare, but as a barrier between me and the screen

outside lighting

  • the problem persists at home, on the street, in the dark, in a lit room, under the sun, under led lamps, under cold light, under warm light. Outdoors in daylight is even worse than indoors, most likely due to the need to make the screen a little brighter - did not help
  • however, in a room that is very brightly lit with neutral temperature LED lamps, for example, in a hardware store, using the phone is a little easier - it helped by 10%

poor eyesight

  • went to see an ophthalmologist for correction. The ophthalmologist's suggestion is that the eyes may be tired due to astigmatism. I was fitted with a lens for an eye with astigmatism and I used a phone in it. It helped by 40% - it relieved some pressure. But: it was still difficult to look into the distance after the phone. An eye with a lens tried to refocus 50 times in a row, dried up and defocused (refused to see the phone clearly), but at least it stopped hurting for a while. Both eyes continued to burn, redden, dry up and be watery.
  • looked at the phone with one eye. It doesn't matter which eye I looked with, as a result, the eye suffered. In addition, although the closed eye did not start to hurt more, it did not relax and did not stop being spasmodic in the closed state. Did not help
  • later had a detailed ophthalmological examination 2 months after buying the phone, no problems other than astigmatism were found

change the phone, what if this is a bad purchase?

  • In a couple of days after buying the S20 FE I went to look at my favorite Xiaomi MI 11 Lite, and exactly 3 seconds later it led to terrible pain in my freshly tortured eyes. Why didn't Samsung lead to the same pain? Because I immediately after purchase applied a film above Samsung and looked through it, so there was a barrier between me and the screen. Did not help

stop using the phone, spend less time with it

  • pain occurs within 1-2 seconds of looking at the screen. In order for the vision problems to remain constant, it is enough to look at the phone 2-3 times a day for 1 second. So, to stop using the phone means to stop using the phone AT ALL, even to make a call or take a picture.

light emission

I tried to use different random materials as barriers, as well as materials that could potentially scatter light.

transparent barriers

  • ordinary glass (which they put in the windows) - did not help
  • random transparent objects and films that came across at hand - did not help
  • sunglasses without polarization - did not help
  • polarized sunglasses - improved by 30%
  • driving glasses with yellow lenses - improved by 20%
  • cycling yellow glasses - improved by 20%

mirror

  • I know that bright led lamps are way more comfortable if you look at them in the mirror. I tried to look at the phone screen through a mirror - it helped 70% (maybe it was an increased distance between me and the phone, but I am not sure)

film and glass screen protectors
There was a comment on another forum that matte ceramic film helped.
Then I found ensete's message that screen protector helped on some phones, it was glass with thermopolyurethane (TPU) in the composition. ensete tried different glasses / films, but only TPU glasses helped him. This suggests that TPU has some properties that other materials do not have.
Speaking of light scattering, single-layer film or transparent real glass do not scatter light well. Some glass, in which each layer refracts light in its own way, and between the layers of glue may be a better subject for testing. Sticking many layers so that there is refraction of light at the joints could also be more helpful. Or some tricky material, like "ceramics".

Hydrogel film (matte)

  • slightly reduced the spasm, but increased the perception of brightness from the screen. Helped by 3%

TPU

  • I found flexible glass (flexiglass), which had TPU in its composition. I put on 1 layer. Helped! By 10-15%. Pasted on top of the second layer. Helped by 30%! Put on the third layer. Helped again. Eventually, I applied up to 6 layers but it was definitely not enough to use the phone.

Ceramic film (matte)

  • applied one layer - helped by 15%
  • ceramic film, and on top of it layers of TPU - it became worse than with one layer of ceramic film. The matte film should obviously go with the top layer. Did not help
  • ceramic film in 3 layers - not enough of improvement
  • 3 layers of TPU, then 3 layers of ceramic matte film - still unusable

Anti-spy glass
That is a screen film that works due to polarization.

  • applied in different combinations. It helped to reduce the amount of light, but somehow either not changed symptoms or even made thing worse

polarizing film
A polarizing film is not a screen protector that sticks to the screen, but one of the layers of the screen, an inner part of a screen. The polarizing film is located above the screen matrix and is responsible for the formation of the picture. Without it, there will be no image on the screen. Among other things, it is responsible for sharpness and contrast. It also reduces the brightness of the image.
I bought a couple of different polarizing films and tried to apply them above the screen - one did not affect the problem in any way, and the second helped by 10%. I don't know if another polarization helped or if just darkening helped. Each direction of the film over the screen will change the picture (in other words, it had to be turned around a lot to find a useful position).

conclusions

All experimental results, as well as subjective feelings when looking at the screen, indicate that the source of the problem is some characteristic of the light emission from the screen, but presumably neither spectrum nor stroboscopic flicker. The matrix itself, the backlight or LEDs, the layers above the matrix through which light passes, anything within the screen.
Here is the hypothesis that was created later, upon meeting two more people who also tried to find a source of the problem within the screen.

    Mrak0020 The ability to look into the distance is called divergence; which these devices seem to make worse for you. Same as @martin who has convergence excess (inability to diverge).

    All of those ophthalmologic tests are great, but do not test for a BVD. I don't think you can rule this out until you find a competent specialist. @martin had no issues at all with his eyesight, including older devices, until newer ones came along.

    You cannot always map symptoms to BVD -- folks get many different symptoms. You can see Dr. Rosner talk about that here at around 2:41.

      ryans yep, I found that later on and I will probably make another post about that a bit later.
      These devices literally kill my ability to diverge eyes.
      But BVD can't explain either light sensitivity, the white veil above a bad screen, or the same symptoms with one eye covered. Also, I have no problems with divergence unless I am exposed. Nor anything that is visible with the Brock string test under normal conditions. My story is very different from Martin's. Including my list of safe devices.
      I wouldn't say devices make my divergence worse, I would say they make it so bad that I am unable to see beyond three meters if I do not use any screen protectors. And they affect it in mere seconds. This pressure feeling reminded me of cross-eyed stereograms, that is how I figured out what is going on.
      I tried to look one eye only a lot of times, simply to limit the exposure. The result is always the same. It hurts 😀
      Based on the number of people who complain about piercing white and eyestrain (that they never had before) on random screens recently, it is something more than a sudden BVD epidemy.

      Influence on vergence

      During the first couple of weeks after the purchase of S20 FE, I noted two weird things.

      • very strange optical illusions resembling a stereo effect while watching movies and using the camera
      • a slight subjective change in the visual location of the object on which I focus (any random thing in real life), correlating with increasing and decreasing of the spasming feeling in the eye. In other words, when looking at an object with only one eye, it may appear slightly to the left or slightly to the right.

      Also, the feeling of pressure that I felt initially reminded me of looking on cross-eyed stereograms or looking at the bridge of my nose, but the pressure direction was different.
      I put two and two together and decided to check what happens if I look at parallel view stereograms.
      At that point, my inability to look far lasted for a week, so it was permanent for the entire week, day and night, and I did not know what caused it. I tried to look at a parallel stereogram, maybe for 5 or 10 minutes (I've never tried them before and it took me some time to understand how to focus)... and a miracle happened, my ability to look far returned. So all it took was one simple exercise.
      I realized that my divergence was affected.
      My happiness lasted for half an hour, 'cause next thing I found was that phone was breaking it back in a second. Every time. I tried to fix it back, the phone was breaking it, and with every circle, it was harder and harder to use my muscles. I was not overdoing exercises, definitely less than 30 minutes per day (rather, 2 minutes 2-3 times a day). My vergence was jumping, I could not properly focus, eye movements became not smooth but like broken. I could not overcome the influence of the screen.

      Comparison with BVD
      I need to say that I do not trust any medical opinion unless it is backed up with solid scientific data (evidence-based medicine). I have not researched how many BVD claims that are made on the websites of some clinics are close to reality, but it seems that at least some of them are questionable. Anyway, I am relying on them for this comparison.

      • BVD leads to symptoms with two eyes open. For me, one open eye is enough for it to hurt and for another closed eye to hurt
      • BVD might lead to light sensitivity based on this 'double vision', which requires both eyes open. My light sensitivity does not go away with one eye open and does not correlate with my double vision. If only one of my eyes is affected by the phone, it will be the eye that gets light sensitivity. My light sensitivity is accompanied by visible red blood vessels on the conjunctiva.
      • BVD is an underlying vision problem. My symptoms completely do not appear under any normal conditions no matter what I do and are tied solely to a specific subset of screens. They are so very strong that if it was BVD I would definitely feel it everywhere else
      • if I put together a normal screen and S20 FE, the latter one will always appear brighter or wrong no matter the settings. If light sensitivity was made by 'double vision', I had to perceive both screens the same way when they were next to each other. Instead, I see a difference when I look at them together.

      And last final thought, correlation is not causation. If I have some BVD that I am not aware of but it doesn't bother me, it doesn't automatically mean that screen hurts me because of BVD.

      a month later

      "conclusions

      All experimental results, as well as subjective feelings when looking at the screen, indicate that the source of the problem is some characteristic of the light emission from the screen, but presumably neither spectrum nor stroboscopic flicker. The matrix itself, the backlight or LEDs, the layers above the matrix through which light passes, anything within the screen.
      Here is the hypothesis that was created later, upon meeting two more people who also tried to find a source of the problem within the screen."

      This is definitely true. I could confirm you without any doubt that the real problem is something with the light emission, because it not only cause me a strong pain in the back of my eyes but also in the skin of my face, arms o hands exposed to the display. Depending on the kind of display, the pain begins to appear after some minutes or one hour and remains by hours or days. It doesn´t happen to me with the natural light, only with most of the led displays manufactured since 2017 and oled displays are even worse. Displays made before this year or with CCFL as a backlight doesn´t cause me any bad effect even if I exposed myself 24hs a day.

      I expected that the spectrum could be the cause but I checked equipments with similar spectrum, some presenting symptoms and others that not, at least that some harmful light were outside of the measured range. So, maybe the cause could be the intensity of the light, and displays with PWM when the light is on emmits very intensive light that overcomes a natural supported threshold. Some old led displays also hurt me but if I set the backlight to the minimum intensity the symptoms dissapear. But this is not the case with newer displyas made after 2017. The symptoms are definitely lower with warmer light than with cooler and using a yellow filter is better for my eyes and skin.

      9 months later

      Hi everyone!

      Have some updates.
      It seems I have slightly adapted to the phone. It is still with me, and I can use it about 30 minutes daily (with breaks) with little or no symptoms. Adaptation happened starting from spring.
      I generally read messages, call, take photos or browse webpages without much troubles. Scrolling still is harmful for me, so I avoid reading, using apps like TikTok or watching videos.

      The effect on blood vessels is still visible and remarkable if I use the phone for prolonged period of time. Red blood vessels, pressure, and inflammation later.

      I use phone with the bunch of TPU screen protectors I mentioned before.

      I see this a a huge victory. The difference between 'can't use tech' and 'can use tech somehow' is drastic.

      8 months later
      20 days later

      Interested in this as well. This is the most detailed experimentation I've seen here, so I have no idea why it didn't make people interested. Would love to have Mrak0020 back here to give some updates if anyone can find a way to notify him

      I'm very interested too, Im having similar problems, so we're waiting for her to come back.

      a year later
      dev