I went to the optician today. Learned that you blink too seldom when you’re looking at screens. The result is that you get dry eyes and/or headache. His advice: For every hour in front of the computer you have to get up and walk for two minutes without looking at your phone. The optimal looking distance for your eyes is about 40 cm (15 inches) and the horizon. That’s where your eyes are the most relaxed (besides from when they’re closed).