I vividly remember getting my first pair of glasses as a child. My mum is very near-sighted and dispatched me to the optician every year. My older sister was diagnosed at around the age of 8 and I prayed I wouldn’t follow suit for fear of being made fun of, but by the time I was the same age, the world was becoming a blur. That year’s visit to the optician confirmed it, and I have worn glasses or contact lenses ever since.

Back then, in the late 1970s, it was quite unusual to need glasses at such a young age. Not any more. Over the past 30 years, there has been a surge in near-sightedness, or myopia, especially among children. Today, around a third of 5 to 19-year-olds are myopic, up from a quarter in 1990. If that trend continues, the rate will be about 40 per cent by 2050 – or 740 million myopic young people.

That is more than an inconvenience. “Myopia is a disease,” says K. Davina Frick at the Johns Hopkins School of Medicine in Maryland, who co-chaired a recent US National Academy of Sciences committee on the condition. “It has wide-reaching quality-of-life and economic implications,” she says, not least the risk of going blind in severe cases. Increasingly, however, researchers think the epidemic can be slowed – or even reversed.

Most cases of myopia are axial, meaning the axis of the eyeball – the distance between the cornea at the front and the light-sensitive retina at the back – grows too long. This means that light entering the eye is focused in front of the…