Occurrences of nearsightedness, also known as myopia, have increased by over 65 percent since 1970 in the US. Myopia, being nearsighted or shortsighted, is a vision condition where the light that comes into the eye does not directly focus on the retina but in front of it. The refractive error causes a distant image to be blurry. In contrast, up close objects are in focus or less blurry.
Myopia begins to develop in childhood and adolescence when the eye grows too much in length. The only way that sight can be corrected is with glasses, contacts, or undergoing surgery.
Nearsightedness in childhood is correctable, not curable, and linked to the development of more severe forms of eye disorders in adulthood. Myopia increases the risk for potential blindness as the retina can become so thin it can lead to a series of health complications such as glaucoma, macular degeneration, and retinal detachment.
Hereditary does play a key role in eyesight. Recently King’s College (London) scientists uncovered contributing genetic abnormalities associated with the condition. The researchers, who all belonged to the Consortium for Refraction and Myopia (CREAM), collected data from over 45,000 people across 32 different studies.
Lead author, Professor Chris Hammond – Frost Chair of Ophthalmology from the Department of Twin Research and Genetic Epidemiology at King’s College London – and his team analyzed the genetic and refractive error data to identify any genes responsible for the disorder. The results, published in Nature Genetics, identified a total of 24 new genes linked to myopia – confirming two previously reported genes.
Though myopia is linked to heredity, research has assessed the possible impact of environmental factors that may explain why rates are rising rapidly in some populations.
Two new studies, published in the May issue of Ophthalmology and the journal of the American Academy of Ophthalmology, shows there is burgeoning evidence that spending more time outdoors may prevent or minimize nearsightedness in children.
Scientists in Taiwan studied 333 elementary students from 2009 to 2010, evaluating how they used their time during recess and its effects on their vision. Previously some of the kids had been using the break to sit indoors, but were asked to spend about 80 minutes outdoors each day with their peers.
Students from a nearby school were used as a control group and were not forced to spend their recess outdoors. A year later, the students at both schools received a follow-up eye exam. The results showed that significantly fewer children became nearsighted or shifted toward nearsightedness in the school that required outdoor recess, compared with the control school.
A separate study of Danish children was the first to show a more direct correlation between seasonal fluctuations in daylight, eye growth, and the rate of progressive nearsightedness. A 2005 clinical trial examined the impact of daylight exposure on eye development through data collected on 235 Danish school children with myopia.
Participants were divided into seven groups, each representing a different seasonal interval. Because daylight hours fluctuate significantly with the seasons in Denmark, from seven hours in winter to nearly 18 in summer, access to daylight was distinct for each group.
Axial eye length – the distance from the front to the back of the eye, which elongates in those with myopia – and vision were tested in each group of children at the beginning and end of their seasonal interval. In the children with access to the fewest hours of daylight, eye growth averaged 0.19 mm; in those with access to the most daylight, eye growth was less at 0.12 mm.
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