Hello everyone!
I am currently researching the topic, experimenting and trying to find a solution.
I made a huge post with the results here (in russian):
Forum 4pda.to
Thread Второй смартфон - болят глаза. Помогите с выбором
Post 568
Sorry for these directions, link approval takes time. I'll post direct link in the next comment.
(Might probably later translate my findings for this forum)
If there are any russian-speaking engineers here, could you please join and contribute? I am coming to conclusion that it might be connected not to backlight but to polarizing film, need to check it out somehow.
I am facing this only on modern phones, but super severe.
Whatever this is, it is some characteristics of light. I have an excellent binocular vision, but this light immediately breaks it leading to my inability to accomodate (or rather vergent) my eyes for far objects. Other than the modern smartphones, nothing can affect my vergence or binocular vision. This light is invisible to vision (brain), or interpreted as non-bright, while for an eye it is super bright. My subjective feeling is that screen is extra bright with any brightness settings and this feeling is widespread when people with this issue have excellent vision. I have no problems with sun or any artificial sources of light except for modern phones. I am trying to find what can create this effect if not PWM. I tested for invisible spectrum and blue light and both were negative in tests. It may be something in direction of light rays.
There also could be something like this: this characteristic is present in led light, becomes much worse with polarizing film and then becomes even worse with pwm or software.
Or other path of light that makes this characterisitic worse and worse, untill it hits even non-sensitive eyes. And then no matter how good is binocular vision, people get eyestrains both from something breaking vergence and from bright light with the physical symptoms like redness or immediate light sensitivity.
Those two things could be connected through the pupil somehow, cause pupil reflectively reacts on light, but also, independently from light, pupil reflectively reacts when focal point is changing distance. This reflex is initiated by movement of vergence muscles and accomodation.