According to https://www.allaboutvision.com/. To reduce your risk of tiring your eyes by constantly focusing on your screen, look away from your computer at least every 20 minutes and gaze at a distant object (at least 20 feet away) for at least 20 seconds. Some opticians call this the "20-20-20 rule."
Blink more often. Blinking is very important when working at a computer; blinking moistens your eyes to prevent dryness and irritation.
Find out more at: https://www.allaboutvision.com/