Why do Screens Cause Eye Strain ?

Normally, we blink about 15-20 times a minute. 

That spreads tears evenly over your eyes, which keeps them from getting dry and irritated. 

But researchers have found that people blink less than half as often when they’re reading, watching, or playing on a screen. 

Also, the contrast of text against the background, the glare, and flickering from digital screens can be hard on your eyes.