Eye will give you this tip

Blink. Chances are, you haven't done that in a while. Now, focus on something 20 feet away for 20 seconds.

• If you do that every 20 minutes, you're following what eye doctors call the 20-20-20 rule.

Why it matters: More than 18 years of our adult lives are spent online, data suggests. That's not great news for our eyeballs.

How it works: When we stare at a screen, we forget to blink and our eyes dry out.

20-20-20 briefly jolts people away from devices and redirects their focus on something else, relaxing eye muscles and encouraging hydrating blinks.

• Plus, patients who follow this rule are "generally happier."

More of the doctor's orders