Is Screen Time Bad for Your Eyes? What the Evidence Says

The short version: Screens do not permanently damage adult eyes, according to the American Academy of Ophthalmology, and there is no scientific evidence that the light from them harms your eyes. What screens do cause is digital eye strain: tired, dry, or blurry eyes and headaches after long sessions, mostly because we blink about half as often while staring at a screen. These symptoms are temporary. The bigger question is for children, where large reviews link more daily screen time with a higher risk of nearsightedness (myopia). Breaks, distance, blinking, and time outdoors are the habits with the best support.

It is eleven at night. You are lying on your side in the dark, phone a hand's width from your face, one eye half shut against the pillow. You finish the video, and the room looks soft around the edges for a second.

We have all done this. We did it last night, if we are being honest, and then woke up with eyes that felt like they had sand in them. So the question is a fair one, and the answer has two parts: what screens do to adult eyes in the short term, and what they might do to children's eyes over years.

Does screen time affect your vision?

For adults, mostly in the short term. The American Optometric Association calls the cluster of symptoms computer vision syndrome, or digital eye strain. It lists:

  • eyestrain
  • headaches
  • blurred vision
  • dry eyes
  • neck and shoulder pain

The AOA says the risk is highest for people who spend two or more continuous hours a day on a computer or other screen. Screens are harder on the eyes than a printed page, it explains, because letters are less sharp, contrast is lower, and glare bounces off the glass.

The reassuring part comes from the American Academy of Ophthalmology. Its guide to computers, digital devices, and eye strain says these symptoms are temporary and that screen use does not permanently damage your eyes. When you rest, they go away.

Why screens tire your eyes out

Three things happen when you look at a screen for a long time.

You blink less. We normally blink about 15 times a minute. The AAO says that while using computers and other digital screens, we blink only about 5 to 7 times a minute. Each blink spreads a fresh layer of tears over the eye, so fewer blinks mean a drier, more irritated surface. That gritty feeling at the end of a long day is usually this.

Your eyes hold one focus for a long time. Looking at something close keeps the focusing muscles inside the eye working. Hours at the same distance tire them, and when you look up, distant things can take a moment to come back into focus.

The setup works against you. Glare from a window, a screen too close or too high, and an old glasses prescription all add to the strain. The AOA points to uncorrected vision problems, poor lighting, and poor posture as common contributors.

What about blue light?

Blue light gets most of the attention and has the least evidence behind it.

The AAO says there is no scientific evidence that the light coming from computer screens damages the eyes, and it does not recommend blue light glasses for computer use. Its own page on screen use for kids repeats the same point.

The best summary of the research on blue light glasses is a 2023 Cochrane review led by researchers at the University of Melbourne. It pooled 17 randomised trials with 619 people. The authors found that blue light filtering lenses may not reduce the short-term eye strain linked to computer work, compared with ordinary lenses. They found no clear evidence either way on sleep or on protecting the back of the eye.

So if your eyes ache after work, a pair of blue light glasses is unlikely to be the fix. Light at night can still affect sleep, which is a separate question from eye health.

Can screen time cause nearsightedness in children?

This is the part worth taking seriously, and it is mainly about children.

Myopia, or nearsightedness, makes distant things blurry. It usually starts in childhood and gets worse as a child grows. It is becoming much more common. A 2016 study in Ophthalmology by Brien Holden and colleagues projected that about half the world's population could be nearsighted by 2050 if current trends continue. The AAO notes that the number of people developing nearsightedness in the United States has nearly doubled since 1971.

Two large reviews have looked at screens specifically.

The 2021 Lancet Digital Health review. Foreman and colleagues pooled the available studies on smartphones, tablets, and myopia. Smart device screen time alone was linked to about 26% higher odds of myopia, and combined with computer use the odds were about 77% higher. The authors were careful: many of the studies measured screen time poorly, and some did not adjust for other factors.

The 2025 JAMA Network Open review. Ha and colleagues combined 45 studies with more than 335,000 participants, whose average age was about 9. Each extra hour of daily screen time was linked to 21% higher odds of myopia. The risk rose most steeply between one and four hours a day, and the authors suggested that less than an hour a day may be a safer range. All the studies were observational, so they show a link and cannot prove the screens caused it.

There is also an honest counterweight. A 2024 umbrella review from the Norwegian Institute of Public Health found the evidence on screens and myopia uncertain and partly conflicting, with prospective studies showing little or no link.

Put together: more screen time and more nearsightedness tend to go together in children. Researchers cannot yet say how much the screen causes, and how much comes from what the screen replaces. Which brings us to the outdoors.

Time outdoors seems to protect children's eyes

The strongest evidence on children's eyes is about daylight.

In a randomised trial published in JAMA in 2015, researchers in Guangzhou, China, added one extra 40-minute outdoor class to every school day for first graders at six schools, and compared them with six schools that carried on as usual. After three years, 30.4% of the children with the extra outdoor time had developed myopia, compared with 39.5% in the other schools.

The AAO's page on screen use for kids says time outdoors, especially in early childhood, can slow the progression of nearsightedness.

So alongside "how many minutes of screen time?", parents can ask a second question: does my child get outside every day? An afternoon at the park does two things for their eyes at once. It is time away from close-up screens, and it is time in daylight.

For the wider picture on how much screen time children of each age should get, our screen time by age guide goes through the AAP's guidance band by band.

How to protect your eyes from screens

The habits below come from the AOA and AAO. None of them needs special equipment.

  1. Use the 20-20-20 rule. The AOA's version: every 20 minutes, take a 20-second break and look at something 20 feet away. A window works well.
  2. Blink on purpose. It sounds silly. It helps. The American Migraine Foundation even suggests a sticky note next to a child's screen as a reminder to blink.
  3. Keep the screen at arm's length. The AAO suggests about 25 inches from a computer screen, and positioned slightly below eye level.
  4. Cut the glare. Move the screen so windows and overhead lights do not reflect off it, and match screen brightness to the room.
  5. Rest after long stretches. The AOA suggests resting your eyes for 15 minutes after two hours of continuous screen use.
  6. Use artificial tears for dryness. The AAO suggests them when your eyes feel dry, and a humidifier can help in dry rooms.
  7. Get your eyes checked. An old prescription, or a vision problem nobody has caught, makes strain much worse. This matters for children too, who often do not notice that the board at school has gone blurry.
  8. Go outside. For children, this is the habit with the best evidence behind it.

Apple's Screen Distance feature

iPhones and iPads with Face ID have a feature called Screen Distance. Apple's support page, What is Screen Distance?, says it uses the TrueDepth camera to notice when you hold the device closer than 12 inches (about 30 cm) for an extended time. It then covers the screen until you move it farther away. It is on by default for children under 13 in a Family Sharing group, and it needs iOS 17 or iPadOS 17 or later.

On iOS 17 through iOS 26, Apple's guide puts it at Settings > Screen Time > Screen Distance. Apple's iOS 27 user guide does not have its own Screen Distance page yet, so check under Settings > Screen Time on a device running iOS 27.

The AAO is lukewarm about it. In an AAO article on Apple's eye features, ophthalmologist Sunir Garg says it will not harm your eyes, but that it is not clear screen distance is the main cause of digital eye strain. He points to going outside, taking breaks, and artificial tears instead.

Where Unglue fits

Most of the advice above is a version of "look up more often." That is easy to agree with and hard to do when the feed keeps going.

Unglue is our attempt at that problem. It keeps the apps you choose blocked until you earn minutes with something real, like a walk outside or a glass of water. On iPhone it works through Apple's Screen Time framework. A short walk to unlock an app is a 20-20-20 break with interest, and if it happens in daylight, so much the better. Yes, we are an app asking you to look at your phone less. We have made our peace with it.

If you want to bring your own total down, our guide to how much screen time is too much has the numbers by age, and the guide to limiting time on specific apps shows how to cap the one or two apps that take the most.

Common questions

Is screen time bad for your eyes?

For adults, screens cause temporary strain rather than lasting damage, according to the American Academy of Ophthalmology. Tired, dry, or blurry eyes after long sessions are common and go away with rest. For children, studies link more daily screen time with a higher risk of nearsightedness, though the evidence cannot yet prove that screens cause it.

Does screen time affect vision permanently?

The AAO says screen use does not permanently damage your eyes, and that eye strain symptoms are temporary. The open question is in children, where long-term links between heavy near work, little time outdoors, and nearsightedness are being studied.

Can screens make my child need glasses?

Possibly, in part. A 2025 review of 45 studies found each extra hour of daily screen time was linked to 21% higher odds of myopia in children and young people. The studies were observational, so they cannot show cause. Time outdoors has the clearest protective evidence: in one Chinese trial, an extra 40 minutes outside every school day lowered the number of children who became nearsighted over three years.

Do blue light glasses help with eye strain?

The evidence says probably not. A 2023 Cochrane review of 17 trials found blue light filtering lenses may not reduce short-term eye strain from computer work compared with regular lenses, and the AAO does not recommend them for computer use.

What is the 20-20-20 rule?

Every 20 minutes, look at something about 20 feet away for 20 seconds. The American Optometric Association recommends it to give your focusing muscles a rest and to remind you to blink.

Is it bad to look at your phone in the dark?

The AAO says there is no evidence that light from screens damages the eyes. Late-night scrolling is still hard on sleep, and the eye strain advice above applies in the dark too: hold the phone farther away, blink, and stop sooner.

How long should I look at a screen before taking a break?

The AOA suggests the 20-20-20 rule for short breaks, and resting your eyes for about 15 minutes after two hours of continuous screen use.

Sources

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