Do Genetics and the Environment Affect Myopia?
Updated: Apr 17, 2021
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Myopia, or nearsightedness, a condition in which a person cannot clearly see “far” distances, is becoming a severe health problem, especially among Asian students. As students spend more “near work” time on electronic devices, and play outside less, myopia rates have been increasing severely. Some researchers pose that myopia could soon become a main blinding cause, due to myopic maculopathy, and other side effects that can cause blindness. In an effort to understand the causes and how to prevent myopia, researchers from BMC Ophthalmology studied 1388 students from grades 1-3 in Wenzhou, China.
The study showed that parental myopia was significantly associated with child myopia. Only 16.7% of the children with no myopic parents developed myopia over a 3 year period, while 20.2% of children with 1 myopic parent developed myopia and 31.5% of children with 2 myopic parents developed myopia. Myopia also progressed faster in the children with myopic parents; they had a quicker rate of elongation (a factor used to measure myopia). Therefore, children with myopic parents are at a greater risk for myopia than children with no myopic parents.
The study also demonstrated that children who spent more outdoor time had reduced rates of myopia. A high level of outdoor time decreased the risk of myopia by 31%. However, the researchers also found that once one has myopia, outdoor time does not slow down progression; in other words, it is only preventative before the onset of myopia.
Therefore, the researchers concluded that an effective way to mitigate the risk of myopia, especially in children with myopic parents, is to increase outdoor time. Their study suggested that high levels of outdoor (non-screen) time was associated with a 58% reduction in the risk of myopia for children with one myopic parent. The influence of parental and environmental factors are not separate; parents will give their children similar environments and behaviours. Therefore, parents with myopia might have spent less outdoor time, and will give their child the same habit, thus repeating a cycle of myopia within a family. In conclusion, in order to mitigate the risks of myopia, although one cannot control one’s genetic history, one can spend more outdoors time, away from eye-damaging screens.