WHERE DOES MYOPIA COME FROM? IS IT NATURE OR NURTURE?
The bad news: there is a clear connection between parents passing their nearsighted genes to their children.
The good news: your genetics are not entirely to blame! Even though myopic inheritance has been established, the steep rise in myopia over the past 50-60 years cannot be due to inheritance alone.
In the graph above, you will notice that in the 1940s, the prevalence of myopia in this select group of East Asian university students was 10% to 37%. If you fast forward to the present, the prevalence is staggering; it is over 80% to 90%! It is impossible for such a sudden shift to have occurred in the gene pool of those nations—so the cause cannot be genetics alone.
In looking for the cause of this progression, researchers studied the visual demands of those university students. It was demonstrated that the average student in Shanghai was responsible for 15 hours of homework per week, compared to 6 hours per week in the United States. Even though the prevailing thought that excessive close work leads to more myopia, they found something else more interesting. They found that it was the lack of outdoor time that led to an earlier and more rapid nearsighted progression! One thing that is clear based on the epidemiological studies, and it is that genetics alone cannot account for this explosive myopic epidemic.
ARE ELECTRONIC DEVICES HARMING MY CHILD’S EYES?
The answer is a complicated “yes.” The logic of excessive screen time worsening vision is sound, but there has been no conclusive evidence that screen time alone contributes to myopic progression. What is known is that with every moment our children are spending time indoors with their eyes glued to screens, they are not spending those moments outdoors. This is where science has stepped in to find a strong correlation between outdoor playtime and the slowed or delayed onset of myopia. Children who spend a couple of hours outdoors every day have been found to be four times less likely to become myopic.
Our stance when it comes to screen time is both scientifically-driven and rooted in common sense. Being outdoors provides the healthy sunlight our eyes and skin need. It’s also fantastic for both physical and visual development. Being less sedentary and more active outdoors enforces better hand-eye coordination, depth perception, and eye coordination skills. All efforts should be made to reduce screen time when possible for these reasons.