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Factors Affecting Myopia in Children

With the advent of computers, smartphones, Facebook and other technological wizardry, outdoor fun and games often take second place in the minds of our children. In some cultures, academic success places intense pressure on kids to read and study.

A report last year from the Organization for Economic Co-operation and Development showed that the average 15-year-old in Shanghai now spends 14 hours per week on homework, compared with five hours in the United Kingdom and six hours in the United States.

There is a worldwide epidemic of childhood nearsightedness (myopia). In Asia, upwards of 90% of young adults need glasses for myopia. In the 1950s, the incidence was 30%.  In the US and UK, myopia rates have doubled in the last 50 years.

For most people, needing glasses or contact lenses is a nuisance. However, a small percentage of children will develop extreme myopia, which can lead to serious eye problems as adults.

While other factors including genetics come into play, the culprit appears to be lack of sunlight exposure. Previously, researchers noted that smarter kids were more likely to be myopic than kids who did less well in school. Thus, the conclusion that reading and studying were the cause of myopia. Wrong!

Newer research shows that the studious kids simply don’t spend enough time outdoors.  Also, it doesn’t matter what kids are doing outdoors – playing, organized sports, reading or just hanging out. The more time outdoors, the lower the risk of myopia. This effect is greatest in those kids with two nearsighted parents, less with one parent and least but still possible with neither parent.

Excessive lengthening of the eye during childhood (not visible when looking at the child) is the cause of myopia. A just-released study from Taiwan showed that stu­dents who spent at least 200 minutes per week outside during school hours have significantly less worsening of nearsightedness and less excessive lengthening of the eyes.

Sunlight exposure, even in the shade, slows down this growth to a normal level. In a study of 6-year-old Chinese children, the addition of 40 minutes of outdoor activity a day reduced the incidence of myopia over the next three years.

March 1, 2019