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How Staring at Screens Affects Your Eyes
The effects may not be long-term, but doctors are seeing more people with screen-related vision problems
If you glance at the news today, order groceries, or schedule a playdate for your child, chances are you’re doing it in front of a screen. Research shows that the average American adult spends up to half their waking hours on a phone or other electronic device. It’s starting to impact physical health in a few detrimental ways — including issues with the eyes.
“It’s something I see on a day-to-day basis,” says Dr. Christopher Starr, an ophthalmologist at Weill Cornell Medicine in New York. “There are so many people who have symptoms from spending time on digital devices.”
Starr, who specializes in ocular surface disorders like dry eye disease, says screen time can affect people differently based on age, underlying health conditions, and the amount of time spent on digital devices like computers, phones, and tablets. There’s no official guideline as to how much time spent looking at screens can cause damage, but Starr says that depending on the person, too much time can result in eye fatigue, irritation, redness, headaches, blurred vision, and more — a constellation of symptoms known as Computer Vision Syndrome, or CVS. Ophthalmologists are seeing an uptick in CVS, Starr says, along with nearsightedness, which experts think is caused by holding screens less than an arm’s length away from the eye, combined with being indoors during screen use. Nearsightedness is expected to affect nearly half of the global population by 2050.
How do screens damage the eye, exactly? CVS encapsulates symptoms like muscle fatigue and headaches, but Starr says that the primary way screens can cause damage is by drying out the eye. According to the American Academy of Ophthalmology (AAO), staring at a screen automatically reduces how often a person blinks and can also result in incomplete blinks. Research shows that people blink an average of 14 times per minute under normal circumstances, but one-third or one-half as often while staring at a screen.
“The role of blinking is to distribute tears across the ocular surface to keep it well lubricated,” Starr says. When this doesn’t happen, dryness depletes what’s called the tear film — the protective layer of moisture and oil that sits on top of the cornea. This, in turn, leads to dry spots on the surface of the eye which can cause irritation and even fluctuations in vision. When the tear film is depleted and you do blink, there’s a potential for friction on the eye’s surface, which creates inflammation that could eventually require medical intervention to fix.
Research shows that people blink an average of 14 times per minute under normal circumstances, but one-third or one-half as often while staring at a screen.
Dryness that accompanies screen use can even change the chemical structure of tears, Starr says. When people fail to blink, the moisture in tear film evaporates, leaving behind salt — a phenomenon called hyperosmolarity. The combination of less lubricant and high salt content leads to more inflammation, which in turn can clog the oil glands that prevent tears from evaporating in the first place. “It’s a vicious cycle,” says Starr.
People tend to practice poor ocular hygiene, which exacerbates the dryness problem. According to research, wearing contact lenses makes dry eye worse, as does keeping screens less than 20 inches from your face.
“We’re not going to avoid screens and computers altogether,” Starr says, “but the best thing we can do is take small breaks, and set up reminders for us to take breaks.” A useful benchmark is the 20–20–20 rule, which means taking breaks from the screen every 20 minutes to focus vision at a point 20 feet away for at least 20 seconds. Specialized computer glasses (available at any optometrist’s office) are also helpful, says Starr, along with omega fatty acid supplements, which are thought to preserve the health of oil glands in the eyelids (though some other researchers debate the usefulness of supplementation).
The AAO hasn’t made any formal recommendations on limiting screen time due to eye damage and experts like Starr agree that screen use is generally safe over the long-term, even if it causes short-term complications. “As far as we can tell there’s no long-term damage in using screens,” he says. “We’re not all going to go blind when we’re 70.”