Short-sightedness – or ‘myopia’ – is on the increase globally. It affects long vision, causing objects at a distance to appear blurred. In myopia, the eye is slightly elongated, so that light coming into the eye from more distant objects focuses in front of the retina at the back of the eye, rather than on it. Retinal cells send signals to the brain to process images, but when the focus is not directly on the retina, the brain interprets the images as being blurred. It is estimated the condition affects up to a third of people in the UK and is becoming more common.
A series of articles recently published in the British Medical Journal (BMJ) assesses the possible reasons for this rapid rise over the last two generations.
It concludes that there is a clear link between the amount of time an individual spends in education and their likelihood of developing short-sightedness. It has long been recognised that the incidence of myopia is greater in those who have been through higher education. This observation alone, however, does not mean that spending more time in education is the cause of short-sightedness. Proving any link between the two has been difficult. It would obviously be unethical to control children’s education simply to enable an assessment of the effect on their eyesight.
Instead, the BMJ reports provide a statistical analysis that brings together the results of various recent research projects. A number of factors potentially have a bearing on individuals’ risks of developing myopia. The research found that genetic factors are highly variable and are thought to account for only a small percentage of cases in the UK. Environmental and social factors are likely to have much more impact. By adopting statistical methods to strip out the effect of genetic variants on educational attainment, researchers were able to analyse whether there exists a causal link between myopia and the level of education that individuals reached. The conclusion is that there is clear evidence that spending more time in education does cause short-sightedness.
Andrew Clayton of Penningtons Manches’ clinical negligence team comments: “Having established a link between time spent in education and the risk of myopia, there is a practical application in mitigating that risk. The research concludes that exposure to natural, rather than artificial light protects against myopia. In fact, the evidence goes on to suggest that lower exposure to natural light has a much greater correlation with the risk of myopia than focusing for long periods on close work, like reading.
“Time spent on education is clearly not the only cause of low exposure to natural light. With the prevalence of screen time in all aspects of life, children in particular are spending less time outside and more time indoors. The authors of this latest report therefore urge parents to encourage children to play outside more, to preserve their eyesight and avoid or delay the onset of myopia. An increasing number of people are having to correct their vision, many of whom are opting for laser surgery. We know from advising clients that laser eye surgery is not always suitable and can cause profound and long-term damage. Avoiding that risk though practical lifestyle choices is far preferable.”