Computer vision syndrome (CVS), or digital eye strain, as it’s also known, results when you spend extended periods using and looking at devices with digital displays. There are several reasons for this. First, and probably most commonly known, a major portion of the visible light that many screen types produce falls within the blue light range. When blue light enters your eyes, it scatters, requiring additional effort to refocus and see properly.

What’s more, most screen types combine pixels—no matter how small and fine, or subtle to your eye—of different colors that contrast to create the images on your screen. Even if you do not consciously notice the difference, the text on your screen is less precise and sharp as the text printed in traditional media, like books, magazines, and newspapers. Text on screens also tends to have a lower contrast between the background and the actual text. Making matters worse, when your screen is made from glass or there’s a lot of light in the room, you may experience a reflection or glare that you must “look past” to see your work. When your eyes try to compensate for these added difficulties, they must work harder to keep everything in focus, eventually overexerting them.

Solution?
Fortunately, it can be remedied with a helpful trick called the 20-20-20 rule: Every 20 minutes, look at something 20 feet away for 20 seconds.