For decades, the prevalence of myopia – or short-sightedness – went from steadily growing to something more dramatic.

The number of children needing glasses was especially intriguing.

The latest study was published this week – an immense systematic review of 276 studies, involving a total of 5.4 million participants from 50 countries across all six continents.

Its main finding? Short-sightedness tripled between 1990 and 2023 – rising to 36 per cent of the global child population.

The other big finding: The increase in myopia was given a boost during and after the Covid pandemic, when children and teenagers became even more reliant on their screen life.

A previous study

In 2009, researchers from the US National Eye Institute compared the prevalence of myopia for American individuals aged 12 to 54 during 1971 to 1972, and from 1999 to 2004.

They found that in the early ’70s, 25 per cent of Americans were short-sighted.

From 1999 to 2004, 41.6 per cent of the population needed glasses.

The researchers noted: “Blurred vision caused by myopia can be treated by corrective lenses (eyeglasses or contact lenses) or refractive surgery.”

But theses remedies were costing Americans billions a year.

The researchers concluded: “The question of whether myopia prevalence is increasing is therefore important to health planners and policy makers.

“Identifying modifiable risk factors for the development of myopia could lead to the development of cost-effective interventional strategies.”

What might these modifiable risk factors possible be?

Is less screen time the answer?

A 2021 study found that “high levels of smart device screen time, such as looking at a mobile phone, is associated with about a 30 per cent higher risk of myopia.

When combined with excessive computer use, that risk rose to about 80 per cent.

Of course, myopia is a complex issue.

On the one hand, getting kids off their tablets and out in the sunshine for a couple of hours every day will do them all manner of good, not just help their eyesight.

On the other, according to a helpful and comprehensive article at The Conversation, for many children, the problem isn’t simply a matter of time spent with the screen, it’s also about the distance the screen is held from the child’s eyes.

The authors advise that simply spending more time outside can delay the onset of myopia.

“Direct sunlight plays a part, as well as the long-range focusing while playing outdoors,” they write.

“Restricting screen time is an option, with optometrist-endorsed recommendations relating to screen times for children.”

For children schooled at home “where limits are not practical, ensure that the screen is not being held or positioned too close to a child, encourage regular breaks and use the 20-20-20 rule”.

This where you need to look 20 feet (seven metres) away from the screen every 20 minutes for 20 seconds. Sounds like great advice, but not so easy to police one imagines.

The authors advise that research has found “that children who go to bed later are more likely to be myopic – an added incentive for parents who are looking for reasons to call it a night”.

Can you see the future?

In 2016, before the pandemic, Australian researchers predicted that half the world’s population (nearly five billion) will be short-sighted by 2050.

Even worse, up to one-fifth of these people (one billion) are “at a significantly increased risk of blindness if current trends continue”.

The authors, from Brien Holden Vision Institute, University of New South Wales Australia and Singapore Eye Research Institute, advise: “The number with vision loss from high myopia is expected to increase seven-fold from 2000 to 2050, with myopia to become a leading cause of permanent blindness worldwide.”