Educated People More Likely to Be Short-Sighted

Henrietta Strickland
June 9, 2018

Currently, 30-50 per cent of adults in the U.S. and Europe are myopic, with levels of 80-90 per cent reported in school leavers in some East Asian countries.

In the new study published in the BMJ on June 6, researchers from the University of Bristol and the Cardiff University examined genetic data of more than 67,000 individuals between the ages of 40 and 69 years old.

For more than a century, observational studies have reported links between education and myopia, but whether time spent in education causes myopia, children with myopia are more studious, or socioeconomic position and a higher level of education leads to myopia has not been known with any certainty. Mendelian randomization analyses were performed in two directions; the first exposure was genetic predisposition to myopia, measured with 44 genetic variants, with years in education as the outcome, and the second exposure was genetic predisposition to higher levels of education, measured with 69 genetic variants, with refractory error the outcome.

An association that is observed using Mendelian randomisation therefore strengthens the inference of a causal relationship.

Every extra year in education increased the likelihood of myopia by -0.27 dioptres. This suggests that a United Kingdom university graduate with 17 years in education would, on average, be one dioptre more myopic than an individual who left school at 16 with 12 years of education. This difference in myopia severity is sufficient to obscure vision for driving underneath lawful benchmarks.

"This evidence suggests that it is poor light rather than reading per se that damages your eyes, and has been one of the main drivers for recent investment in bright light classrooms to protect against myopia in southeast Asia".

The researchers point to some study limitations. The participants who contribute to this database are typically healthier, highly educated, and report fewer health problems compared to the rest of the population. However, there was little evidence that this could explain their findings.

In a linked editorial, Professor Ian Morgan at the Australian National University and colleagues say the evidence suggests that it is not only genes but environmental and social factors that may have major effects on myopia.

The significantly higher prevalence of myopia in Asia has been speculated to be due to the intense academic pressure encouraging indoor studying and reduced time spent outdoors.

Another reason, according to Dr. Denize Atan, the lead author of the study, is that students are less exposed to natural sunlight because they spend most of their time indoors. Children from developed East and Southeast Asian countries regularly say that they spend less time outdoors than children from Australia or the USA and randomised controlled trials have shown that more time spent outdoors during childhood protects against the development of myopia.

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