Long-term and prolonged computer use can lead to eye dryness. Use of computers, and also display devices with a screen, decreases the number of eye blinks, leading to incomplete blinking and evaporation of tears. Staring at a computer screen can reduce the number of times a person blinks by 30%. This can lead to eye strain and dryness.

Eyes need to stay moist to stay healthy. Normally, people blink every 10 seconds or so. When you blink, your eyes release a “tear film” that soothes and coats your eyes. But you don’t blink as often when you’re on a tablet, computer, or watching TV. Less blinking means drier eyes.

There’s more to your tears than just water. Oil and mucus are in them, too. You need all 3 substances to keep your eyes moist and comfortable. A 2014 study in Japan found that people who spent hours on their computers had a lower amount of mucus in their tears (Web MD).