The trouble started every day at around 3 p.m., after Cathy Higgins had spent five or six hours staring at an array of computer screens at her desk. Her university job overseeing research projects involved peering closely at numbers and details on contracts, applications and budgets.

“My vision was so blurry, I couldn’t even see what was on the screen, and I was squinting so much that I could not function,” Higgins said.

When her eyesight got bad, Higgins walked around and spoke with members of her staff. She began planning in-person meetings for afternoons. But she would resume the computer work late at night.

“If I had to continue working through the blurry vision, that’s when the migraines would happen,” Higgins said.

Digital screens are pervasive, not only at work but in our homes, schools and shops. An estimated 104 million Americans of working age spend more than seven hours a day in front of screens, according to the American Optometric Association. All that screen time can take a toll.

Too much exposure to screens can lead to dry or watery eyes, fuzzy vision and headaches. It can also lead to myopia, or nearsightedness, in some people, especially children.

One reason for the discomfort is that staring closely at screens for prolonged periods causes the muscle that helps eye focus to tighten up.

“That muscle’s not supposed to stay tight all day long. And if it does, it’s like picking up a light weight and trying to hold it over your head for hours,” American Optometric Association President Steven Reed said. “It’s not hard to pick it up. But after a while, even though it’s not a heavy lift, your body just gets tired.”

Here are some tips from eye health professionals to reduce strain.

Follow the 20-20-20 rule

Take a break from sitting at a computer every 20 minutes. During the break, focus your eyes on something that’s about 20 feet away for 20 seconds. Pausing close-up work and looking at something in the distance gives tired, tight muscles time to relax.

“Luckily, eye strain is temporary,” said Raj Maturi, an ophthalmologist at Midwest Eye Institute in Indianapolis. “The best way to avoid these symptoms is by taking breaks from our screens or near work activities and using lubricating eye drops, if needed.”

People usually blink about 18 to 22 times per minute. But when looking at a screen, the rate drops to three to seven times per minute, according to the Cleveland Clinic. That’s where eye drops come in.

Change your desk setup

Some people find that using a larger computer monitor helps reduce eye fatigue. You can also increase the font size on your laptop, monitor or smartphone screen.

Sitting an arm’s length away from your screen and adjusting it so you’re looking slightly downward also can help reduce eye strain, according to the American Academy of Opthalmology.

Be wary of product claims

Some products, such as blue light glasses, are marketed with claims that they will reduce digital eye strain, improve sleep and prevent eye disease. But several studies have found the glasses are not very effective, according to the American Academy of Opthalmology. It’s really our behavior with digital devices that causes symptoms, not the small amount of blue light coming from screens, the group said.

Sleeping soundly

The blue light that digital screens emit can increase alertness, so watching Netflix on an iPad or scrolling through social media feeds in bed may make it hard to get restful sleep.

Doctors recommend turning off screens one to two hours before going to sleep. You can also set devices to “dark mode” in the evening to reduce. If you’re used to streaming videos at night, try listening to an audiobook or podcast instead.