Abstract
PurposeHyperopia (farsightedness) has been associated with a deficit in children's educational attainment in some studies. We aimed to investigate the causality of the relationship between refractive error and educational attainment.MethodsMendelian randomization (MR) analysis in 74,463 UK Biobank participants was used to estimate the causal effect of refractive error on years spent in full-time education, which was taken as a measure of educational attainment. A polygenic score for refractive error derived from 129 genetic variants was used as the instrumental variable. Both linear and nonlinear (allowing for a nonlinear relationship between refractive error and educational attainment) MR analyses were performed.ResultsAssuming a linear relationship between refractive error and educational attainment, the causal effect of refractive error on years spent in full-time education was estimated as −0.01 yr/D (95% confidence interval, −0.04 to +0.02; P = 0.52), suggesting minimal evidence for a non-zero causal effect. Nonlinear MR supported the hypothesis of the nonlinearity of the relationship (I2 = 80.3%; Cochran's Q = 28.2; P = 8.8e-05) but did not suggest that hyperopia was associated with a major deficit in years spent in education.ConclusionsThis work suggested that the causal relationship between refractive error and educational attainment was nonlinear but found no evidence that moderate hyperopia caused a major deficit in educational attainment. Importantly, however, because statistical power was limited and some participants with moderate hyperopia would have worn spectacles as children, modest adverse effects may have gone undetected.Translational RelevanceThese findings suggest that moderate hyperopia does not cause a major deficit in educational attainment.
Highlights
In the first few months after they are born, the majority of infants have a low level of hyperopia.[1]
This work suggested that the causal relationship between refractive error and educational attainment was nonlinear but found no evidence that moderate hyperopia caused a major deficit in educational attainment
Translational Relevance: These findings suggest that moderate hyperopia does not cause a major deficit in educational attainment
Summary
In the first few months after they are born, the majority of infants have a low level of hyperopia (approximately +2.00 diopters [D], on average).[1] Over the 3 to 6 years, this hyperopia reduces in magnitude in most infants through the process of emmetropization. Some infants do not emmetropize but instead maintain a relatively high degree of hyperopia throughout this period and on into adulthood.[2] Children with hyperopia are prescribed spectacles either to provide clear vision as their accommodation is not effective enough to compensate for their hyperopia or to alleviate their eyestrain symptoms.[3,4,5]. Randomized controlled trials (RCTs) suggest that prescribing spectacles to 7- to 11-month-old infants with hyperopia of +3.50 D or more reduces the risk of strabismus and amblyopia.[6,7,8] there is no consensus on whether prescribing spectacles to asymptomatic school-age children for lower levels
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