More Years of School Correspond to More Nearsightedness

Jenni Laidman

July 21, 2014

More education was associated with a higher prevalence of nearsightedness in a study of more than 4500 people, and myopia worsened with additional years of schooling, according to a study published online June 17 in Ophthalmology.

Alireza Mirshahi, MD, from the Department of Ophthalmology, University Medical Center Mainz, Germany, and colleagues analyzed the association between education level, including professional postschool education, and myopia in 2367 men and 2291 women aged 35 to 74 years. All were participants in the Gutenberg Health Study, a population-based, prospective, observational cohort study with 15,000 participants.

The researchers excluded patients with a history of refractive or cataract surgery from the trial. Laboratory tests extended to genetic analyses in a subset of 3593 participants. Investigators documented education level and postschool professional education. To diagnose myopia, a spherical equivalent (SE) was determined via noncycloplegic autorefractometry. Covariates in the study were age, sex, and 45 single nucleotide polymorphisms associated with myopia.

Germany uses a 3-track education system in which students enter 1 of 3 paths at grade 4, depending on elementary school performance: 1 track graduates at 9 years, another at 10 years, and the third at 13 years. The research found among those who graduated at 13 years, 50.9% (790/1553 people) had an SE of −0.5 or less. Nearly 20% (19.2%; 298/1553) had an SE of −3 D or less. Among those who graduated after 10 years, 41.6% (419/1008) were myopic. Among those who graduated after 9 years, 27.1% (520/1916) were myopic, and among those who never graduated, 26.9% (7/26) were myopic (P < .001 for all).

Myopia was more prevalent among university graduates than secondary vocational school graduates. Among university graduates, 53% (592/1118) had an SE of −0.5 D or less, and 20.6% (230/1118) had an SE of −3 D or less, whereas 34.8% (269/773) of secondary vocational graduates had an SE of −0.5 D or less and 11.3% (87/773) had an SE of −3 D or less. Among primary vocational school graduates, 34.7% (749/2157) had an SE of −0.5 D or less, and 9.9% (213/2157) had an SE of −3 D or less. Among those with no professional training, 23.9% (88/368) had an SE of −0.5 D, and 4.9% (18/368) had an SE of −3 D (P < .001, for all).

The association remained after adjusting for age, sex, and known myopia-associated single nucleotide polymorphisms, suggesting the growing global increase in myopia results not from genetic factors but from environmental change, the authors write.

"The association between myopia and the level of education is most probably universal," Dr. Mirshahi told Medscape Medical News. "The effect of genetic contribution to myopia is smaller than that of environmental factors; in this case, education. All the [single nucleotide polymorphisms] account for approximately 0.1 diopter."

Dr. Mirshahi and colleagues calculated an odds ratio to see whether less myopic patients, with a larger spherical equivalent, are less likely to graduate in 10 or 13 years instead of graduating after 9 years. They calculated an odds ratio of 0.49. "That means that with every increase of the spherical equivalent by 1.0, the probability to graduate after 13 years will decrease by approximately one half (49%)," Dr. Mirshahi said.

The results of this study could explain earlier findings that myopia prevalence is lower in older groups in the Gutenberg Health Study cohort. "It is implicit that some of this age difference could be the result of increasing educational standards," the authors write.

The authors have disclosed no relevant financial relationships.

Ophthalmology. Published online June 17, 2014. Abstract

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