The only thing that helped me was to take regular breaks from looking at a screen. My daily habit now is that, at least once per hour, I get up and take a walk

The only thing that helped me was to take regular breaks from looking at a screen. My daily habit now is that, at least once per hour, I get up and take a walk around the block. This hugely improved my eye strain problem as well as a few other physiological oddities. Actually going outside seems to be a critical part of this. Just strolling around the office doesn't have the benefits.