I think the problem is that we all have different neurological / optical / other issues and have problems trigerred by different technology aspects. For example - I get different strain from PWM, different from non-PWM while with others I don't get strain in the eyes but feel nausea, head pressure, neck tension and so on.
On some devices I've had problems with I believe it's dithering or PWM, but with my new Surface Pro that's giving me this head pressure I believe it might be its backlight. The screen itself is nice, but there is something strange in color of its backlight - I even notice it while not looking directly and get this feeling within seconds, I bet getting tired with dithering would require more time.
This may be a specific frequency, excess of wave at specific length or some other property of LED light. I'm really getting tired of looking for a new device that I could use as my daily laptop, to the level I think of keeping this Surface although it seems to pump my head up. At least it doesn't tire my eyes, so seems like a fair trade-off š