Myopia (also known as near-sightedness or short-sightedness) is the most common eye problem in humans, affecting about a quarter of the global population. Myopia is a refractive error of vision: As light passes through the cornea and lens, images form in front of the retina instead of on the retina itself. As a result, close objects look clear but distant objects look blurry. Myopia most commonly begins during childhood. Symptoms include failure to see distant objects clearly, complaints of headaches and eye strain from trying to focus on distant objects, squinting to better see the blackboard/whiteboard in school and other objects in the distance, and sitting too close to the TV. For years it’s been thought that the tendency for children to develop myopia is inherited; if one or both parents are myopic, chances are higher their children will also be affected. And while there also appear to be ethnic differences in the incidence of myopia, a new study of German children suggests that a child’s lifestyle may be the most important factor. Anne Harding reports that researchers found that children who spend more time outdoors and who play sports are less likely to develop myopia:
The study team found that myopic children spent less time outdoors, had lower levels of vitamin D, had a higher body mass index and were less likely to play sports than children who weren’t nearsighted. While being of non-European descent, having a mother with a low education level and low family income were also associated with myopia, the researchers found that lifestyle factors explained most of these risks.
Can myopia be prevented? One of the study’s authors says so and advises children to play outdoors for at least 15 hours a week and limit “near work” to no more than 45 minutes in one sitting:
“Differences in myopia prevalence between ethnic groups that have commonly been assumed to be down to genetics may in fact be due to differences in lifestyle between ethnic groups,” Dr. Jeremy Guggenheim, an optometry professor at Cardiff University in the UK, told Reuters Health in an email.
“The new study and other recent work suggests that this preventative effect of time outdoors is beneficial even at very young ages, e.g. 3 – 6 years-old,” said Guggenheim…
“Too much close work, such as reading and using hand-held devices, may also be a risk – although the jury is still out on this question,” he added.
Until the past few centuries, myopia was potentially a fatal defect, leading to an early demise for the human who couldn’t see the lion in the distance, or the edge of a cliff a few meters away, or like Mr. Magoo, anything that wasn’t directly in front of his face. From an evolutionary standpoint, it’s easy to see how lifestyle could affect the refractive powers of the eyes. Solutions of modern medicine — glasses, contacts, surgery — lessen the existential impact and allow us, thankfully, to carry on.