Even if you don't wear glasses for distance or reading, consider getting computer glasses. Computer glasses have the blue-light filter mentioned in other posts,

Even if you don't wear glasses for distance or reading, consider getting computer glasses. Computer glasses have the blue-light filter mentioned in other posts, with slight magnification that helps your eyes relax while focused on a computer monitor. Take frequent breaks and focus on objects at different focal depths (stare out a window and count leaves, look for patterns in clouds, mentally trace a pattern across an opposing office building)