"Education and IQ
A number of studies have shown the incidence of myopia increases with level of education, and many studies have shown a correlation between myopia and a higher intelligence quotient (IQ).
A 2008 literature review writes that studies in several nations have found a relationship between myopia and higher IQ and between myopia and school achievement. A common explanation for myopia is near-work. Regarding the relationship to IQ, several explanations have been proposed. One is that the myopic child is better adapted at reading, and reads and studies more, which increases intelligence. The reverse explanation is that the intelligent and studious child reads more, which causes myopia. Another is that myopic children have an advantage at IQ testing which is near-work because of less eye strain. Still another explanation is that pleiotropic gene(s) affect the size of both brain and eyes simultaneously. According to the two most recent studies, higher IQ may be associated with myopia in schoolchildren, independent of books read per week.
Other personal characteristics, such as value systems, school achievements, time spent in reading for pleasure, language abilities and time spent in sport activities correlated to the occurrence of myopia in studies."