You really ought to be treating your eyes like you do your feet—especially if you’re part of the 60 percent of Americans who spend at least 5 hours a day staring at digital devices, according to the Vision Council.

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That’s because the more devices you look at from different distances, the more strain you put on your eyes while trying to adjust to the screens.

You generally view your desktop monitor, for example, from a distance of around 26 inches, says Mark Rosenfield, Ph.D., of the State University of New York College of Optometry. But your eyeballs creep closer to your laptop, tablet, and smart phone.

That’s why he recommends asking your eye doctor for a custom lens prescription for each device you use.

You might sport one prescription at night and on weekends—when you’re most likely to use your phone or tablet—and the other when you’re at your office and working on your desktop.

Still, no matter what prescription you use, spending too much time glued to your devices can be bad news for your eyes.

Gaze at your smartphone, laptop, or TV long enough and you’ll experience dry, tired, or aching eyes, as well as headaches or blurred vision.

These symptoms make up something called “computer vision syndrome,” says Rosenfield.

When you keep your eyes peeled on a screen for long periods of time, you don’t blink as often or produce enough tears.

And the cells on top of your cornea—the dome-shaped surface in the front of your eye that needs to be well-lubricated—start to flake away, causing dry eyes.

One way to help your tired eyes: Follow the “20-20-20” rule. Every 20 minutes you’re using your phone or computer, focus on something 20 feet away for 20 seconds.

Temporarily shifting your focus will produce more lubrication, which can reduce the symptoms you feel when your eyes become dry.

Additional reporting by Christa Sgobba

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