Why myopia is on the rise: causes, risks and what helps

Short-sightedness – myopia in medical terms – is becoming more common worldwide, particularly among children and young adults. Here you can find out about the causes, the risks and what can be done for children – including the open questions.

The numbers: almost one in two people could be myopic by 2050

A widely cited analysis (Holden and colleagues, 2016) pooled 145 studies with around 2.1 million participants. It estimated that about 1.4 billion people were short-sighted in 2000 – just under 23% of the world’s population. For 2050, the team projected around 4.8 billion, or 49.8%. Over the same period, the number of people with high myopia (defined in this study as −5 dioptres or more) could rise from 163 million to 938 million.

In Europe, an analysis of 15 population studies (Williams and colleagues, 2015) found myopia in 47% of 25- to 29-year-olds – about 1.7 times the rate among 55- to 59-year-olds (around 28%). In urban areas of East and South-East Asia, according to a 2025 Cochrane review, more than 80% of young people are myopic by the time they finish secondary school.

What happens inside the eye

In most people with myopia, the eyeball has grown too long. Light from distant objects therefore comes to a focus in front of the retina rather than on it – far-away things look blurred, while near things stay clear. This lengthening happens mainly in childhood, and the younger a child is, the faster myopia usually progresses.

Blur is not the only issue: in an elongated eye, the retina is stretched. Specialists therefore also pay attention to the length of the eye in millimetres.

Genes or environment?

Myopia partly runs in families: according to a review by the International Myopia Institute (IMI, 2021), having one or two short-sighted parents raises a child’s risk. But genes cannot explain the rapid rise – the gene pool barely changes over a few generations, whereas lifestyles change quickly.

Two environmental factors in particular are considered causally linked:

• Education: Genetic analyses point to a genuine cause-and-effect relationship. A study cited in the Cochrane review estimated about 0.27 dioptres more myopia for each additional year of education – around 40% of this was explained by less time outdoors.
• Little time outdoors: According to the IMI, the protective link with time outdoors is stronger and more consistent than the link with close work.

And screens? A 2025 meta-analysis (Ha and colleagues) of 45 studies with around 335,000 participants, aged 9 on average, found that each additional hour of screen time per day was linked to roughly 21% higher odds of myopia, particularly in the range of one to four hours. The data come mostly from observational studies and do not prove cause and effect – screen time is often indoor time as well. According to the IMI, there is no evidence that a tablet is more harmful than the same time spent with a book, and in East Asia the rise began long before smartphones. With close work, long uninterrupted stretches and a short reading distance may matter more than total time.

Daylight as a protective factor

One particularly telling piece of evidence comes from Guangzhou, China (He and colleagues, JAMA 2015): six primary schools added a daily 40-minute outdoor activity class for first-year pupils, and parents were encouraged to take their children outdoors after school, at weekends and during the holidays. Six other schools served as a comparison. After three years, 30.4% of the children in the outdoor group who had not been myopic at the start had become short-sighted, compared with 39.5% in the comparison group.

It seems to be the light that matters, not the exercise: according to the IMI, indoor physical activity showed little protective effect. Studies treat a light level above 1,000 lux as a sign that someone is outdoors. In animal studies, at least 10,000 to 20,000 lux seemed necessary to slow eye growth noticeably, but there are signs that 2,000 to 5,000 lux may already be effective in humans. One theory is that bright light releases the messenger substance dopamine in the retina, which slows the eye’s growth in length – a mechanism well studied in animals. Fittingly, myopia progresses more slowly in summer than in winter.

How much is worthwhile? Several studies suggest that around two hours a day outdoors can offer meaningful protection. Taiwan introduced programmes across its school system to give children more time outdoors, after which the proportion of children with reduced visual acuity initially fell. Importantly, daylight mainly helps to delay the onset of myopia; whether it slows myopia that is already present is less clear.

Why every dioptre counts

Glasses make vision sharp again – but the elongated eye stays as it is. A meta-analysis from Rotterdam (Haarman and colleagues, 2020) shows how the risk of complications rises with the degree of myopia (odds ratios, compared with people who have no refractive error):

The figures come from observational studies and describe groups, not individuals – but they show that even low myopia is not entirely risk-free. A risk model (Bullimore and colleagues, 2021; cited in the Cochrane review) estimates that people with −8 dioptres spend an average of almost ten years of life with visual impairment, compared with about 4.4 years at −3 dioptres.

This also applies after correction: glasses, contact lenses, laser eye surgery or an implantable contact lens (ICL) correct the refractive error, but they do not shorten the eye. If you are highly short-sighted, it is a good idea to discuss with your ophthalmologist how often check-ups make sense.

Warning signs: A retinal detachment is an emergency. If you suddenly notice lots of new spots or threads in your vision, see flashes of light, or a dark shadow spreads across part of your field of vision, go to an ophthalmologist or an emergency department straight away. There is more on this in our guide to flashes and floaters.

Myopia control in children: what the studies show

Myopia control treatments aim to slow the eye’s growth in length. The 2025 Cochrane review analysed 104 studies involving 17,509 children aged 4 to 18. In the control groups, myopia increased by a median of 0.65 dioptres per year. This is how much less progression was seen after one year:

Orthokeratology – rigid lenses worn overnight – slowed the eye’s growth by about 0.18 mm after one year (moderate certainty). However, contact lenses, especially those worn overnight, can increase the risk of a sight-threatening corneal infection (microbial keratitis), so careful hygiene is essential, and any eye symptoms should be checked promptly by an ophthalmologist. Our article on contact lens hygiene explains what good lens care involves.

Higher doses of atropine work better but more often cause glare sensitivity and blurred near vision; after stopping higher doses, myopia is also more likely to speed up again (rebound). According to the Cochrane review, lower doses have fewer side effects, but their effect is also smaller and less certain. Whether and in what form atropine drops are an option for a child is something to discuss with an ophthalmologist.

Repeated low-level red light therapy has also shown effects in short-term studies in children in China, but the evidence is very uncertain and, according to the Cochrane reviewers, safety concerns have been raised – so it should only be considered after an assessment by an ophthalmologist. The Cochrane reviewers’ conclusion: the treatments may slow progression, but results are inconsistent, and it remains unclear whether the effect lasts over the years.

What you can do

• Get out into daylight: Plan plenty of outdoor time for children – studies point to around two hours a day. It does not have to be sport; playing outside counts.
• Take breaks from close work: Not proven, but easy to do: regular breaks from reading and screens, not holding things too close – and keeping track of daily screen time.
• Have children’s eyes checked early: Especially if parents are short-sighted, an eye examination for the child can be worthwhile. Whether myopia control is an option depends on factors such as age and how quickly the myopia is progressing – a decision for an ophthalmologist.

The ophthalmology service at My Laser Vision in Wallisellen includes a children’s check-up and the measurement of visual acuity and dioptres among its basic examinations.