Yep... focusing (as in, your eyes keeping focus) on a thing that's at a fixed distance infront of you for extended periods of time seems to be very bad for your eyesight... "back in my times", the parents used to blame stuff like this on screens (tv back then), but books do the same thing. Basically all the workplace safety trainings here include the "stare at something in the distance every now and then", so you focus on something else, not just the screen <1m away from your face.