Should have spent more time outdoors? (Image: Veer Solus/Getty)

The decline was rapid. I got my first pair of glasses aged 9, and by my mid-teens could no longer read the title on the cover of New Scientist at arm’s length. With my mum’s eyes just as bad, I always assumed that I’d inherited my short-sightedness from her and that I could do little to stop my vision from becoming a little blurrier each year.

Around the same time, however, rates of short-sightedness, or myopia, were rising to epidemic proportions around the world. Today, in some of the worst-affected countries such as Singapore, Hong Kong and Taiwan, around 80 per cent of young adults are myopic, compared to only 25 per cent a few decades back.

Rates are lower in western countries – between 30 and 50 per cent – but myopia seems to be rising steadily here too. What could be causing this mysterious epidemic? It is clear that genetics alone can’t explain the condition, and the long-standing theory that reading was to blame has failed to play out in subsequent studies.

Large-scale epidemiological surveys ensued, which have pinned down the specific aspects of modern lifestyles that cause children’s eyesight to deteriorate. With just a few simple measures, it now looks like we could easily prevent future generations from descending into my blurry world.

While the causes have been elusive, the anatomy of myopia has been well understood for decades. In the normal eye, the lens focuses light squarely on the retina, which records the image and sends it to the brain. We myopes, however, have eyeballs that are elongated, increasing …