It has long been observed in different countries (e.g., Israel, the United States, and New Zealand) that myopic children have higher intelligence quotient (IQ) test scores. While an explanation for the association of myopia with higher IQ is lacking, it has been hypothesized that there may be a link between eyeball axial length and cerebral development, or that both myopia and IQ may be influenced by the same genes.
Singapore Chinese children aged 8 to 12 years with higher nonverbal IQ, as measured by the nonverbal Raven Standard Progressive Matrices, were more likely to be myopic, after controlling for age, gender, school, father’s education, parental myopia, and books read per week. Higher nonverbal IQ scores were also associated with greater axial lengths. Our data suggest that nonverbal IQ has an association with myopia independent of near work in young Singapore students, though the mechanism underlying the nonverbal IQ-myopia relationship is not well understood.
A positive association of myopia with higher academic performance, reading ability, and IQ test scores has long been recognized, of which only a few examples will be cited here. Cohn et al. noted a century ago that persons who were intellectually gifted or scholarly were more likely to be myopic. Observations over the past few decades include apparent increases in the frequency of myopia among intellectually able individuals, such as university and medical students.