A modern epidemic in sight

An epidemic of short-sightedness, or myopia, is sweeping the world.

The problem was first noticed in East Asia, where now up to 96 per cent of teenagers are short-sighted. In Europe and US, this figure is around 50 per cent compared with 25 per cent 50 years ago.

Estimates suggest that very soon 2.5 billion people, that is a third of the world’s population, will be myopic.

Babies’ eyes grow rapidly, reaching near-adult size by 10 years of age. Myopia results when this growth is altered and the eyeball is elongated. This causes the lens’ focus to be shifted from the retina to slightly in front of it, resulting in blurred vision. Although vision can be corrected with glasses, contact lenses or surgery, it increases risk of eye diseases – retinal detachment, glaucoma and cataracts – in later life.

So what is the cause of the myopia epidemic and how can it be prevented?

For years, myopia was claimed to be a genetic problem, but to account for the recent dramatic rise there must be additional environmental factors.

As this rise coincided with Asian children spending more time studying (15-yearolds in Shanghai have on average 14 hours per week of homework), and most children, irrespective of nationality, poring over smartphone and computer screens, too much close-up work seemed the obvious answer.

Some experts still back this theory, but several large comparative studies on children’s daily routines do not. Instead, the only environmental risk factor uncovered by these studies is lack of time spent outdoors. The results show that children who spent less time outdoors have a greater risk of myopia regardless of time spent studying. The key to protection from myopia seems to be the eye’s exposure to bright light.

The scientific reasoning behind this finding is unknown, although animal experiments suggest that a deficiency of light-stimulated chemicals in the retina can block normal eye development.

Whatever the fault, prevention is not difficult to devise – send the children outside for more sunlight, more physical activity and overall a more healthy existence.