Joel Hunter, MD Refractive Surgeon, Hunter Vision Updated 08/28/17 12:23 PM
Have you ever had one of those packs of Ramen noodles that costs a quarter? I have. I had one for dinner tonight. And I did it for one reason: I think they’re delicious. My seven-year-old son had a project at school creating a book with opposing pages each listing his dad’s favorite and his favorite in different categories. For favorite food, it said, “My favorite food is lobster bisque / My dad’s favorite food is ramen.” It filled me with pride as if I was a coal miner who lived a life of labor and grime so my son could enjoy the finer things. I probably read too much into it.
The point here is I like ramen, but I don’t ever let Luke eat ramen. And if you’ve ever had it—or even if all you know of it is that it costs 25 cents—you know why. I’m positive it isn’t very good for me. I have never felt the desire to do anything after eating ramen except drink water and lay on my side. If something makes us feel bad, we assume we should probably protect our kids from it. In the case of ramen, this is accurate. In the case of eye strain and fatigue from backlit screens, it’s more complicated.
Tired Eyes Don’t Mean Damaged Eyes
When we look at a computer screen for a few hours, our eyes get tired. This fact leads naturally to the idea that it must hurt our eyes. Interestingly enough, it doesn’t. At least, not in the way you’d think. Damage to the eye on a structural or functional level can only happen if the eye is damaged. For instance, you may have rolled your eyes so hard at that obvious statement that you pulled a muscle. But that’s the point. Some physical force of change is needed to cause an eye injury, and there isn’t one to be found in the light coming from your screen.
What About UV Light?
It’s a myth. Not ultraviolet light in general, clearly that exists, or else you’d never need sunscreen or be able to fondly remember the roller skating rink from middle school skate nights. But the idea that UV light from backlit screens can damage your eyes is verifiably untrue. There is no UV light coming from your screen. Your eyes receive more UV light in one walk to get the mail than they will in a lifetime of looking at a screen. So we can rule that out as a source of damage.
When’s the Last Time You Blinked?
The real reason we get eye strain from a computer, tablet, or phone screen is because we stare at it for a long time. Two things happen during all that staring. We focus up close for a long time without taking a break, and we don’t blink. If you focus at near for a long time, the muscle in your eye starts to fatigue. It gets all crampy and spasms. Then you try to look across the room and everything is blurry because your focusing muscle takes a minute to relax again.
Adding to the strain and blur, our eyes dry out because we don’t blink when we are focusing on a screen. Some poor soul—I think of this nameless, sad junior researcher often—took on the task of counting blinks per minute observed during people’s performance of various tasks. When we are chatting or unoccupied, the average blinks per minute is around 16. When we are reading or focusing on a screen, that average drops down to about four blinks each minute. It feels bad and looks blurry when we let our eyes get unpolished. And that’s exactly what happens when the layer of tears on our eyes evaporate because we’re not blinking.
In a surprise twist, guess who is all but immune from these two problems? Kids! They can focus up close all day and their eye doesn’t give a hoot. Young lenses are so flexible and easy to focus that their eye muscles are almost fatigue-proof. And the layer of tears found on most kids’ eyes is amazing. Have you ever tried to have a blinking contest with a kid? It’s like trying to win a blinking contest with a photograph. They’re unbeatable. Since they have borderline magic tears that never evaporate, they’re also nearly immune to the eye strain caused by dryness we experience with blinking less.
How to Refresh Tired Eyes
For adults, screen time can make your eyes feel strained and the solution to both the focusing and the dryness from no blinks is the same: look across the room on purpose at regular intervals. The snazzy-named 20/20/20 method is to look 20 feet away or more for at least 20 seconds about every 20 minutes when working at the computer. Or you could just walk around for a minute if you’re looking for a less regimented solution. More and more people these days need to walk around anyway so whatever activity monitor they’re wearing doesn’t send them some digital message of disapproval. “You haven’t stood up in two hours!” Maybe just tell me the time and mind your own business, Apple watch.
A Brain Issue, Not an Eye Issue
For kids, screen time isn’t likely to cause problems or symptoms for their eyes. The brain using those eyes is the reason screen time should be monitored and intentional. Multiple studies confirm that passive screen time—just watching whatever is on the screen without interacting with it—should be limited. Shows that encourage participation and video games that develop hand eye coordination have merit. But all of these options don’t hold a candle to genuine social interaction with parents and friends. As a bonus, you can really boost their self-esteem while developing your own character if you’re willing to challenge them to a blinking contest.