We have unlearnt the skill to stare into the distance. By focusing solely on computer screens and sheets of paper, our eyes have lost the habit of staring into the horizon with a subsequent rise in the incidence of myopia in industrialized countries. It is the most common sight disorder in the United States (one and a half billion people in the world), marking an increase from 25 per cent in 1972 to 42 per cent in 2004.
But books, TV and computer screens are seemingly innocent this time. And neither are carrots and cranberries considered as a cure-all. The major enemies of myopia are the hours we spend outdoors. This was initially noticed a few years back, and a study presented at the American Academy of Ophthalmology – currently underway in Orlando - confirms that every additional hour spent outdoors by children and adolescents during the week diminishes their likelihood of becoming myopic by 2%.
Hence, the beneficial effects of outdoor life are not limited to maintaining physical fitness, and metabolism. There are two feasible reasons that underpin the theory of outdoor life as protection against myopia. Firstly, natural light, which is far brighter than the light shed by electric bulbs, protects the shape of the ocular bulb by stimulating the production of dopamine in the retina (dopamine is a neurotransmitter that also limits growth of the ocular bulb); secondly, when we step outdoors, our eyes are naturally inclined to focus on the farthest objects, or even on the horizon, if we happen to be outside the city.
The study conducted by the British university combines the results of eight studies that have been carried out during the past four years on a total number of 10.400 children and adolescents. They were observed by measuring the quality of vision and lifestyle. While the association between healthy eyes and time spent outdoors was evident, no data was found to the prove that myopia is the direct consequence of hours spent on books, watching TV or, however, focusing on objects placed at an approximate distance of 30 cm.
Those who watch a lot of TV but compensate by spending several hours outdoors do not present a higher risk of myopia than those who scorn the remote control. Besides, the theory that reading and focusing on electronic screens “tires the eyes” causing ocular bulb deformation (a disorder that is determined by inherited genes to a good extent) has now been debunked. Moreover, sports activities seem to serve no purpose in maintaining long-distance vision if they are practiced in indoor gyms and sports facilities.
It is certainly no mere chance that studies conducted in Australia reported eagle-eyed children, regardless of genetic heritage. The country that prides in bright sunlight and wide horizons counts more hours of outdoor activities for its youth (14 a week) than Singapore (barely 3 hours a week), the capital city of lost dioptres.
- Source Mido365
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