And all that extra screen time is taking a toll on your eyes.

“Working from home has given us more hours to look at computer screens,” says Tanya Polec, OD, a vision rehabilitation specialist at VQ Vision in Tucson, AZ. “The more stress we put on our visual system, the more likely we are to do permanent damage.”

It’s time to take a long, hard look at how screens affect your eyes and set your sights on some new habits.

Your field of vision

When you’re on your computer, you engage just 1% of your field of vision. The fovea, a tiny depression at the center of the retina where visual acuity is highest, does all the heavy lifting while the rest of your vision goes unused. That’s like spending an hour at the gym on nothing but your triceps.

Leaning on your close-up vision, Polec says, can hurt your ability to see at a distance. “It can cause a slight increase in the physical length of the eye.” This lengthening of the eye can lead to nearsightedness, or myopia, where you can only focus on what’s up close, not on objects in the distance.

Blinking is key

Another problem with all that screen time: staring. When your eyes are fully relaxed (think: gazing off into the distance), you may blink as often as 22 times per minute, or about every three seconds. But blink rates plummet by up to 66% when you’re in front of a computer.

To be clear, you blink less under any close-up conditions, even when you’re reading printed pages. But studies show that when you’re staring at computers and other lighted screens versus reading a book, you’re more likely to start a blink that you don’t finish.

An incomplete blink is when the eyelid lowers but doesn’t completely cover the pupil before it retracts. Even under the best circumstances, up to 2 in 10 attempted blinks may not be completed. But when your eyes are fixed on a screen, they leave even more blinks unfinished.

A lot happens in the blink of an eye. Tears spread across the eye’s surface to keep it lubricated. Without tears, eyes get dry, irritated, and tired. Your vision could also blur or double, and you may get headaches, too.

Tears aren’t just water. They contain mucus and oil. Tiny glands in your eyes called meibomian glands produce this oil, called meibum. When you blink, the glands release the lubricating oil.

“When we don’t blink, the glands can’t be expressed. Then they don’t fill and they may start to disappear,” Polec says. Like muscles that atrophy with lack of use, these glands have a “use it or lose it” policy, too. This can cause permanent damage to the quantity or quality of your tears and lead to chronic dry eye.

The 20/20/20 rule

Following the 20-20-20 rule addresses a lot of these computer-induced eye problems. For every 20 minutes that you look at a screen, stop for 20 seconds, and look 20 feet into the distance. It takes the pressure off the fovea, engages the rest of your vision, and picks that blink rate back up.

Polec suggests you take this advice a step further. “Go for a walk. You’ll look around. You’ll look further away and open up that side vision.” This might explain why studies in children have shown that those who spend more time outdoors – where they use their entire field of vision – are less likely to develop nearsightedness. When you’re indoors all day, you can only cast your gaze so far.

Adjust brightness and glare

When your device is brighter than your surroundings, your eyes have to work harder. Dimming the brightness of your screen to match the lighting around you can help prevent digital eye strain, according to the American Academy of Ophthamology.

Go analog

When possible, work on paper rather than on a screen. That is, write in a notebook and read from a printed page. You’re still engaging close-up vision only, but at least you’ll finish more of the blinks you start.

A word about eye drops

Artificial tears are a temporary fix. It’s ok to use them occasionally, but long-term use can further harm your eyes’ natural ability to lubricate themselves and lead to chronic dry eye. 

Take a load off

Some people lighten the load on their eyes with a pair of computer glasses. Even if you don’t need regular glasses, you might find that these specs ease digital eye strain. They are like reading glasses except that readers help you zero in on objects about 15 inches from your face and computer glasses magnify what’s about 24 inches away. You’ll need to see an optometrist to get the right pair.

If you already wear glasses but still get screen-related eye strain, you may find that a computer-specific prescription is easier on your eyes while you’re at your desk. 

“If you’re working more than three to four hours on the computer, which is probably most of us,” Polec says, “you’re going to need to reach into your pocket to buy glasses for that use.”