More screen time is linked to a higher chance of short-sightedness (myopia) in children, and the risk climbs fastest between about 1 and 4 hours a day. Screens aren’t the whole story, though: time outdoors is one of the few things shown in a randomised trial to lower the number of children who become short-sighted, so the most useful change is often less screen time and more daylight.
Myopia means distant things look blurry while close things look sharp. It happens when the eyeball grows a little too long. Once a child is short-sighted, it usually gets worse as they grow, which is why both prevention and slowing it down get so much attention.
What the latest research says about screens and myopia
The biggest analysis so far pooled 45 studies with more than 335,000 participants. Published in JAMA Network Open in February 2025, it found that each extra hour of daily screen time was linked to 21% higher odds of myopia.
The link wasn’t a straight line. The odds rose only slightly at 1 hour a day, then more steeply up to 4 hours, when the odds were roughly double. The authors suggested a possible “safety threshold” of under 1 hour a day of screen use.
| Daily screen time | Odds of myopia compared with no screen time |
|---|---|
| 1 hour | About 5% higher (OR 1.05) |
| 4 hours | About 97% higher (OR 1.97) |
| Each extra hour (average across the range) | About 21% higher (OR 1.21) |
Two caveats matter. Most of the studies were snapshots taken at one point in time, so they show a link, not proof that screens cause myopia. And the authors rated the certainty of the evidence as low. Children who spend hours on screens also tend to spend less time outside and more time on other close-up tasks, and it’s hard to separate these effects.
Is it the screen, or the close-up focus?
Probably both, plus what the screen replaces. Researchers think several things are at work:
- Near work: phones and tablets are held close, often closer than a book, for long stretches without breaks.
- Less time outdoors: an hour on a tablet is often an hour not spent outside in daylight.
- Family history: the NHS notes that short-sightedness often runs in families, and says it’s not fully clear why it happens.
A small phone held 20 cm from the face for an hour isn’t the same as a TV across the room for an hour, even though both count as “screen time”. If your child does use screens, distance and breaks matter.
Why outdoor time protects children’s eyes
This is the part with the strongest evidence. In a trial in Guangzhou, China, six schools added a 40-minute outdoor class to every school day and six didn’t. After three years, 30.4% of children in the outdoor schools had developed myopia, compared with 39.5% in the other schools (JAMA, 2015).
Bright daylight is thought to slow the eye’s growth, though the exact mechanism isn’t proven. Indoor lighting is much dimmer than outdoor light, even on a cloudy day. The American Academy of Ophthalmology suggests at least one to two hours of outdoor time each day.
Outdoor time doesn’t have to be sport. Walking to school, playing in a park, reading on a balcony or eating lunch outside all count. In winter, short daylight trips still help. Don’t forget sun protection in summer and warm layers in winter. If you live somewhere with long, dark winters, our article on vitamin D and winter sunlight covers the other side of getting outside.
How much screen time is OK for kids’ eyes?
There’s no single number everyone agrees on, but the main guidance points the same way:
| Age | Guidance | Source |
|---|---|---|
| Under 1 year | Screen time not recommended | WHO |
| 1 year | Sedentary screen time not recommended | WHO |
| 2 to 4 years | No more than 1 hour a day; less is better | WHO |
| School-age children | Reduce recreational screen time to 1 to 2 hours a day, with 1 to 2 hours outdoors | American Academy of Ophthalmology |
Schoolwork on a laptop is hard to avoid, so focus on the screen time you can control: leisure gaming, videos and scrolling.
Eye-friendly screen habits: a checklist
- Use the 20-20-20 habit: every 20 minutes, look at something 20 feet (about 6 metres) away for 20 seconds. The AAO recommends this for children.
- Prefer a bigger screen further away (TV or laptop) over a phone held close.
- Set a kitchen timer or device limit so breaks actually happen.
- Keep screens out of bedrooms and off for an hour before bed. It helps sleep too.
- Agree on screen-free zones, such as meal times and the car on short trips, and follow them yourself.
- Swap one screen session a day for something outdoors.
- Book regular eye tests, even if your child isn’t complaining.
Screens can also dry the eyes because we blink less while staring at them. Our guide to dry eyes and screens in winter explains why. Blue light, by contrast, isn’t the cause of myopia. We cover what it does and doesn’t do in the truth about blue light.
Signs your child might be short-sighted
Short-sightedness usually starts between the ages of 6 and 13, according to the NHS. Children rarely say “I can’t see”. Instead, you might notice them:
- Struggling to read the board at school or road signs
- Sitting very close to the TV or holding a tablet close to their face
- Squinting or screwing up their eyes to see things far away
- Getting headaches
- Rubbing their eyes a lot
Teachers often spot it first, so it’s worth asking at parents’ evening.
Can myopia be slowed once it starts?
Yes, there are now treatments that aim to slow how fast the eye grows, on top of glasses that sharpen vision. The American Academy of Ophthalmology lists:
- Low-dose atropine eye drops, used at bedtime in children aged about 5 to 18. Side effects may include redness or itching around the eye.
- Specially designed glasses that blur side vision slightly. In the US, the FDA has approved such glasses for children aged 6 to 12.
- Peripheral defocus contact lenses, worn by children aged about 8 to 12.
- Orthokeratology (ortho-K), rigid lenses worn overnight to reshape the front of the eye temporarily.
Availability and cost vary a lot between countries. In the UK, the NHS says myopia management lenses aren’t available on the NHS because more research is needed, though children under 16 get free NHS eye tests. In the US and India, ask a paediatric ophthalmologist or optometrist what’s offered locally.
Slowing myopia matters because higher myopia raises the chance of eye problems later in life. The AAO names cataract, glaucoma and retinal detachment.
When to see a doctor or optometrist
Book an eye test if your child:
- Has any of the signs above
- Has a parent or sibling who is short-sighted
- Hasn’t had an eye test in 2 years (the NHS suggests going at least this often)
- Already wears glasses and seems to be struggling again
Get urgent help the same day if your child has sudden loss of vision, sees a shower of new floaters or flashes of light, has a shadow or “curtain” across part of their vision, double vision, an eye injury, or a painful red eye. Go to an eye emergency service or call your local emergency number (911 in the US, 999 in the UK, 112 in the EU and India) if they’re hurt.
Frequently asked questions
Can screens cause permanent eye damage?
Screens can cause tired, dry or sore eyes, but these usually ease with breaks. The concern with heavy screen use in children is the higher chance of myopia, which is long-lasting once it develops.
Does reading books cause myopia too?
Long periods of any close-up work may add to the risk, but nobody is suggesting children read less. Take breaks, hold books at a comfortable distance and read outside when you can.
Will glasses make my child’s myopia worse?
No. Glasses correct blurry vision. Not wearing them doesn’t slow myopia, and it makes school harder. Ask about myopia control options if you’re worried about it getting worse.
Is 2 hours of screen time a day too much for a 10-year-old’s eyes?
It’s within what the AAO suggests (1 to 2 hours of recreational screen time). Pair it with at least 1 to 2 hours outside and regular breaks, and the overall balance is reasonable.
Do blue light glasses prevent myopia?
There’s no good evidence that they do. Outdoor time, screen breaks and, where needed, myopia control treatments are the options with evidence behind them.
This article is for general information and is not a substitute for advice from a doctor. If you have symptoms or a health condition, please consult a qualified healthcare professional.
