So basically nobody really knows what causes the eye strain. I'm beginning to think the problem of eye strain is a multifaceted issue. For me the following measures collectively have made a difference. I can't say which one of them is the most effective one, since they all seem to help:
- Increasing the font size and sitting further back, because it's easier to focus on "far and big" than "near and small". Also, near and small forces your eyes to converge (at the extreme you'd be crossing your eyes), which is also tiring.
- Using the Night Light function in Windows (basically a blue light filter I think, the screen turns reddish).
- Adjusting display brightness to match ambient light levels.
- Using a monitor with deeper blacks for better contrast (this enables you to turn down the brightness even further and still see detail).
- Using a flicker-free display. My Samsung phone is not flicker-free and it starts raping my eyes within seconds.
- Placing the monitor at a comfortable viewing height, that is, with the top bezel slightly below eye height.
- Using a larger display because a bigger screen keeps my eyes moving and refocusing all the time, depending on which part of the screen I'm looking at. On a small screen eye movement is more constrained and feels a bit like sitting in a plane seat for hours which can cause discomfort and you feel the need to stretch your legs.
- Placing a light behind my monitor pointed at the wall to create a light bias. This results in a more even distribution of light over the retina, rather than just a bright rectangle surrounded by darkness.