Screen time and children’s eyes. What parents should know

Most parents are aware that too much screen time is probably not great for their children. But what does it actually do to their eyes, how much is too much, and what are the signs that screens are causing a problem worth taking seriously?

The answers are more nuanced than the headlines suggest. Some concerns are well-founded and backed by good evidence. Others are overstated. This guide tries to be straight with you about which is which.

Does screen time damage children's eyes?

The short answer is that screens themselves do not damage the eyes. There is no good evidence that looking at a screen causes permanent harm to the eye's structure or function. The light emitted by modern screens, including blue light, is not at levels that cause retinal damage in normal use.

What screens do cause, particularly with extended use, is eye strain. The eyes have to work hard to maintain focus on a screen at a fixed distance for long periods, blinking less often than usual in the process. This leads to discomfort, tired eyes, headaches, and temporary blurring. It is real and worth taking seriously, but it is not permanent damage.

The more significant concern with children and screens is different, and it is about myopia rather than eye strain.

Myopia and the time spent indoors

Myopia, or short-sightedness, has been increasing rapidly in children across the world over the past few decades. In the UK, rates have roughly doubled since the 1960s. Globally, the figures are higher still. Researchers have been working to understand why.

The strongest evidence points not to screens specifically but to time spent indoors doing close work, combined with insufficient time spent outdoors. Sunlight appears to play a protective role in eye development during childhood, and children who spend more time outside are significantly less likely to develop myopia or develop it later and more mildly.

Screens matter in this picture because they are part of what keeps children indoors, focused on close distances, for long stretches of time. But reading books, doing homework, and other close indoor activities carry a similar risk. The screen itself is not uniquely harmful. The pattern of behaviour it encourages is the issue.

Myopia that develops in childhood tends to progress through the school years and stabilise in the late teens or early twenties. Higher levels of myopia carry a greater risk of certain eye conditions in later life, including retinal detachment and glaucoma. This is why the trend matters beyond just needing stronger glasses each year.

What are the signs that screens are affecting your child's eyes?

Children are not always good at articulating visual discomfort, particularly if it has built up gradually. Things to watch for include:

• Complaints of headaches, particularly after school or screen time
• Rubbing the eyes frequently during or after using a device
• Sitting closer to the television than they used to, or holding devices very close to the face
• Squinting at the screen or at things in the distance
• Losing their place when reading, or avoiding reading more than usual
• Tired or sore eyes at the end of the day
• Difficulty concentrating on close work

Some of these symptoms are also associated with an uncorrected prescription rather than screen use specifically. If your child is showing several of them, an eye test is the right first step. An optician can separate what is caused by screen strain from what might indicate a prescription problem or something else worth investigating.

How much screen time is too much?

Official guidance varies and tends to be general. The NHS advises limiting recreational screen time for children, particularly under five, and encourages parents to set boundaries around screen use before bed. Most guidelines focus more on the context of screen use than on precise hour limits.

From an eye health perspective, the most useful thing is not counting hours but managing how screen time is done. Continuous use for long stretches without breaks is harder on the eyes than the same total time spread across shorter sessions with regular pauses.

The 20-20-20 rule, which applies to adults too, is a practical habit: every 20 minutes, look at something at least 20 feet away for 20 seconds. For younger children this needs to be built into the routine by a parent rather than self-managed, but it genuinely helps reduce the eye strain that accumulates with sustained close focus. We cover this in more detail in our post on digital eye strain.

What actually helps

Time outdoors. This is the most evidence-backed intervention for reducing myopia risk in children. Current research suggests at least 90 minutes of outdoor time per day offers meaningful protection. It does not need to be sport or structured activity. Playing outside, walking to school, and time in the garden all count. The key factor appears to be exposure to natural light rather than the physical activity itself.

Regular breaks from close work. Building in screen breaks, encouraging children to look up and across the room regularly, and avoiding long unbroken sessions of reading or device use all reduce the strain placed on the focusing system.

Good lighting. Screens in dark rooms create high contrast that the eyes have to work against. Reasonable ambient lighting in the room where screens are used reduces this strain.

Appropriate viewing distance. Devices held very close to the face increase the demand on the focusing muscles. Encouraging children to hold phones and tablets at a comfortable arm's length rather than close to their nose makes a difference.

Screen-free time before bed. Screens before bed affect sleep quality through a combination of the stimulating content and the light exposure. Poor sleep affects concentration and makes eye strain symptoms worse the following day.

What about blue light glasses?

Blue light blocking glasses are widely marketed as a solution to screen-related eye strain and sleep disruption. The evidence for them is weak. Large-scale reviews have not found meaningful benefit for eye strain or sleep quality compared to no glasses at all.

The strain people feel from screens is much more likely to be caused by reduced blinking, sustained fixed focus, and extended close work than by the blue light wavelength specifically. Addressing those causes is more effective than filtering the light.

If your child needs glasses for a prescription reason, wearing them while using screens is of course sensible. But buying blue light glasses without a prescription reason is unlikely to make a noticeable difference.

When should you get your child's eyes tested?

NHS eye tests are free for all children under 16, and there is no minimum age. The NHS recommends testing before school age, and then every one to two years throughout childhood. If your child is showing any of the symptoms listed above, do not wait for the next scheduled test.

Children are often not aware that their vision is not quite right, particularly if it has changed gradually. A child who seems to be managing fine at school may still have a prescription that is making things harder than it needs to be. Regular testing catches this before it affects learning or causes unnecessary strain.

If you have a family history of myopia, earlier and more frequent testing is advisable. Myopia has a strong genetic component, and children of short-sighted parents are significantly more likely to develop it themselves. For a full picture of what a children's eye test involves and what to expect, our guide to children's eye tests in Barking covers the process from start to finish.

At Iology in Barking, we test children of all ages. If your child uses screens regularly and has not had an eye test recently, it is worth booking one. Most of the time everything is fine, and knowing that is worth something in itself.