Myopia in children: why it is rising and what studies say about outdoor time and screens

In the second year of primary school he could read the board from the last desk. In the fourth he starts to squint, and the teacher moves him to the front row. It is a story many parents know: myopia in children usually appears during the school years, when the eye lengthens a little more than it should.

Today this story concerns many more children than a generation ago. A 2025 meta-analysis, which brought together 276 studies with more than 5.4 million children and teenagers in 50 countries, estimates that the share of myopic children rose from about 24% in 1990 to about 36% in 2023¹. Why does it happen, and what can be said with the evidence in hand about the outdoors, books and screens?

In this article

1. Myopia in children: how common it is
2. Why it appears: family, study, environment
3. Time outdoors and myopia: the school studies
4. Near work and screens: a more uncertain link
5. Why age matters
6. Frequently asked questions
7. Sources

Myopia in children: how common it is

The 2025 meta-analysis found higher percentages in East Asia, in cities, among girls and above all among adolescents, in whom myopia affected 47%¹. If the trend continues, the authors project that in 2050 about 40% of children and teenagers will be myopic, over 740 million people¹.

In Europe the picture is different. A 2025 meta-analysis of 22 studies in 14 European countries, with over 128,000 people, considered separately the studies in which vision had been measured after drops that relax the focusing muscle for a few hours (cycloplegia). In these studies myopia affected 5.5% of children aged 6 to 11 and 25.2% of those aged 12 to 17². Without the drops the values were higher, 31.2% against 18.9% overall: a technical detail that weighs heavily on the figures you see quoted².

In Europe, in short, myopia arises mainly between the end of primary school and lower secondary school; why the dioptres then keep rising into adolescence we explain in the article on what myopia is.

Why it appears: family, study, environment

A 2023 review of studies that followed groups of children over time found that children of myopic parents develop myopia more often, and that girls have a slightly higher risk, about 1.3 times that of boys³. The same authors warn, however, that the quality of the evidence on individual factors is moderate to very low³.

Genes, on the other hand, do not change in a generation: to explain such a rapid rise we also have to look at how children grow up. An International Myopia Institute review lined up the evidence with a strict criterion, asking not only whether a factor is associated with myopia, but whether there is evidence that it causes it⁴:

• years of education: the causal link was confirmed by Mendelian randomisation, a method that uses genetic variants as a sort of natural experiment;
• time outdoors: its protective effect on the onset of myopia was confirmed by randomised trials;
• near work, that is, reading, writing, looking at things up close: associations generally weak and inconsistent, although supported by a meta-analysis;
• screens: weak and contradictory evidence.

Time outdoors and myopia: the school studies

Time outdoors has been tested by randomly assigning whole schools to programmes that take children outside for longer.

In Taiwan a study of 693 first-year primary-school children in 16 schools found that, in the schools with the outdoor programme, myopia increased less: 0.35 dioptres against 0.47⁷. According to the authors strong sunshine may not be necessary: even staying outside longer in less intense light, under trees or in an outdoor corridor, is an option to consider⁷.

Putting together five randomised trials with 10,733 primary-school children, a 2024 Cochrane review found that after two years about 23 children in 100 had become myopic in the groups with more outdoor time and about 27 in 100 in the comparison groups, with moderate-certainty evidence⁵. It is a real but modest effect, and the differences in dioptres were small⁵.

One point remains open: does time outdoors also slow a myopia that has already appeared? A 2017 meta-analysis found no link with the speed of worsening in children who were already myopic⁸; the Taiwan study, however, saw a benefit in them too⁷.

Near work and screens: a more uncertain link

A meta-analysis of 27 studies and over 25,000 children aged 6 to 18 found that more time spent reading, writing and doing close-up activities is associated with a slightly higher probability of myopia, about 14% more⁹: a modest association.

On screens the numbers are more striking. A 2025 meta-analysis of 45 studies and over 335,000 participants, with a mean age of 9, found that each additional hour a day in front of a screen is accompanied by a probability of myopia about one fifth higher; the curve rose mainly between one and four hours a day, and then more slowly¹⁰. But these are observational studies: they show that the two things go together, not that one causes the other; a child who spends many hours in front of a tablet, for example, might spend fewer outdoors. How to read these data we describe in the article on children and screens.

Why age matters

In the European data, going from the 6–11 group to the 12–17 group, the share of myopic people becomes almost five times higher². A myopia that appears early has more years to grow before stabilising, and for this reason research looks at two moments. The first is before myopia appears: here time outdoors is the intervention with the best evidence^4,5. The second is the years after diagnosis, when treatments to slow the lengthening of the eye are studied: low-dose atropine eye drops and myopia control lenses. These are choices to be assessed with the ophthalmologist, case by case.

Frequently asked questions

At what age does myopia usually appear in children?

Usually during the school years. In the most rigorous European studies 5.5% of children aged 6 to 11 and 25.2% of those aged 12 to 17 were myopic².

How much time outdoors is needed against myopia?

The studies have not identified a threshold valid for everyone. In the Shanghai study the risk fell by 15–24% with 120–150 minutes a day outdoors in full light⁶; in the Taiwan one even less intense light seemed useful, as long as the time outside was long⁷. In school programmes the overall effect was modest⁵.

Do screens cause myopia?

Meta-analyses find an association between hours of screen use and myopia¹⁰, but the studies are observational and an International Myopia Institute review judges the evidence weak and contradictory⁴. Whether screens, in themselves, cause it remains to be shown.

If the parents are myopic, will the child become myopic?

Not necessarily, but the risk is higher: in the reviews children of myopic parents develop myopia more often³. The rapid rise in recent decades indicates, however, that environment and habits matter too^1,4.

Myopia in children is not a fault to be shared out between parents, school and tablets: in the growth of the eye, what counts is genes, years on books and daylight⁴. The factor with the clearest evidence is also the simplest, time spent outside, which in schools has reduced new cases slightly, but measurably⁵.