by Patrick Appel
I asked why eyeglasses are associated with intelligence. A reader's answer:
Sitting here wearing metal-framed glasses. Diagnosed with myopia at age 7, long before undergrad or grad school, never mind reading blog posts. High IQ (150+), early reader (age 3). My parents (a child psychologist and a teacher/author) figured that my nearsightedness may have promoted early reading because I was more comfortable focusing on a page than on the horizon.
There is some research suggesting it may be some kind of genetic of developmental issue. For instance, the study "IQ and the Association with Myopia in Children" at found that nonverbal IQ was more closely correlated with myopia than number of books read per week, the paper "Myopia, Intelligence and the Expanding Neocortex" at hypothesizes that there might be some change in gene expression which both increases the amount of gray matter and increases the likelihood of myopia (along with allergies), and the paper "Myopia as a latent phenotype of a pleiotropic gene positively selected for facilitating neurocognitive development, and the effects of environmental factors in its expression" similarly suggests that there may be genes which affect both brain development and eye growth.
I've often heard that in poor performing schools one of the biggest problems turns out to be that many of the children who need glasses don't have them. It's possible that people with glasses were able to go farther in their education than their equally capable but less fortunate counterparts.