Children’s eyesight is getting worse. This is what parents can do about it

This is Everyday Science with Clare Wilson, a subscriber-only newsletter from The i Paper. If you’d like to get this direct to your inbox every week, you can sign up here. Hello, and welcome back to Everyday Science. When I was at school in the 1970s and 80s, it was unusual for children to need glasses – and wearing them gave you the aura of being a swot. Today, it is more common, and the rise is projected to continue, with about four in ten British children needing glasses for short-sightedness by 2050. In some East Asian countries, rates are astonishingly high – over eight in ten children wear glasses in Singapore, for instance. Shorts The degree of children’s short-sightedness is also getting worse, the consequences for which are much more than just the inconvenience of wearing glasses: severe short-sightedness also makes people more prone to eye diseases in later life. But there are several ways the trend could be halted, with new support from two recent studies – but most people aren’t aware of them. As a primer, short-sightedness means things that are close-up are clear, but those far away are blurry. Long-sightedness means the opposite, when distant things are in focus, but near things are blurry. (I remember this with the phrase: “You say what you see”.) Both conditions are caused by the eyeball being the wrong shape. With perfect eyesight, images are focused on the retina, at the back of the eye. When vision is good, light rays are focused to form an image on the retina at the back of the eye, shown on the right with the inverted apple (Photo: Getty) In short-sightedness, the distance between the front of the eye and the retina is too great – the eyeball is too long. This means the focusing is correct when it comes to light rays from near sources, but rays from distant sources are focused at a point slightly in front of the retina, and hence are blurry. In long-sightedness it’s the opposite. In the UK, short-sightedness is rising at a rate of 0.7 per cent per year, which leads to the prediction of a rate of 40 per cent by 2050. Don’t (just) blame screen time or reading To understand why, it is helpful to know that babies are usually born slightly long-sighted, and as they grow and develop over their first year, their eyeballs usually grow into the “right” size to achieve good vision over all distances. But in some children there is overcorrection and the eyeball ends up becoming too long, and hence short-sighted. Scientists have a good idea why that happens. Contrary to old myth, it is not (exactly) spending too much time reading, nor its modern-day equivalent, looking at screens. It is a lack of time spent outside. While those who spend more time reading or using screens may tend to spend less time outdoors, large studies that have tracked how children spend their day point to lack of time outside being the key thing that correlates with short-sightedness. There are two competing theories as to why. One is that as children’s eyeballs develop during childhood, they naturally grow to be good at seeing things close up rather than far away, because the child is simply not using their distance vision enough. “The eyes are becoming more short-sighted because our needs are more geared towards close sight,” said Manoj Parulekar, an ophthalmologist at Birmingham Women’s and Children’s Hospitals. “When you put a child outdoors, they are no longer focusing on close-up objects. Their eyes are relaxing, and that drive is reduced.” The other idea is that our eyes need the brighter light that we are exposed to outdoors. Even on the cloudiest days, sunlight is much brighter than indoor light. Animal research suggests that bright outdoor light encourages the release of signalling molecules by the retina that help the eyeball to grow to the correct size. Regardless of the mechanism, the discovery is good news because it suggests that we can slow or even reverse the trend by encouraging children to spend more time outdoors – which will probably also be helpful for their exercise levels too. This has support from several sources. In Taiwan, schools introduced a policy of getting children outside for at least two hours a day in 2010 to tackle their rising rates of short-sightedness. And it worked. Afterwards, rates fell from 50 per cent to 46 per cent, reversing the long-term trend of year-on-year rises. Randomised trials also support outdoor time as a way of reducing new development of short-sightedness – although not as a way of reversing it when it has already begun. Why children’s short-sightedness is worth fixing For children who have already become short-sighted, other interventions are possible, though, and optometrists are increasingly suggesting them to parents, said Parulekar. Generally short-sightedness starts in childhood and worsens for a while until it stabilises in young adulthood, when the eyes stop growing. So, treatments are generally aimed at slowing this worsening. One strategy is the use of eyedrops every night until the age of about 16, containing a medicine called atropine. A trial from June showed that over two years, this reduced the eventual degree of short-sightedness by 0.33 dioptres (D, the unit used in typical prescriptions measuring curvature of the lens required to fix eyesight). The treatment is currently being reviewed by Nice for NHS use. A different approach is wearing special glasses that both correct the vision defect and help slow worsening of the short-sightedness. The only downside is that they are generally more expensive than ordinary glasses. A trial published this week found that such glasses reduced short-sightedness by 0.64D over two years. These are relatively small effects, considering that in primary school children the short-sightedness typically worsens by about 0.6D a year, before slowing in teenage years. There may well be larger impact if used longer term. But even a small effect could still be worthwhile because children who end up severely short-sighted, defined as -6.0D or greater, are more prone to various serious eye conditions in old age, including retinal detachment and a degenerative condition called macular degeneration. “You have a quite high risk of having serious complications later in life,” said Augusto Azuara-Blanco, an ophthalmologist at Queen’s University Belfast, who carried out the trial of eye drops. It seems that the stretching of the eyeball to greater proportions makes the retina thinner and more vulnerable to detaching, or to developing cracks that can encourage degeneration. “Perhaps the tissues are less strong – they have been overstretched,” said Azuara-Blanco. Whatever the explanation, while children and teens once just had to put up with wearing glasses, it is encouraging that there are new ways to lessen their eye problems. And for those who haven’t yet reached that stage, preventative measures could be as simple as spending more time playing outside. I’ve also written Cancer vaccines given as treatment for the disease have moved a step closer after promising results in a landmark trial of skin cancer patients. I’ve been watching If, like me, you dabble in the Marvel Cinematic Universe, I strongly recommend the latest movie, Spiderman: Brand New Day. I couldn’t recall exactly why, in Spiderman’s last outing, all of our hero’s friends and girlfriends had had their memories of his identity wiped, but it didn’t matter. The premise meant that the film had to blend the usual saving-the-world plot with a moving exploration of the value of human connections – no matter how important your job.