A study of 300,000+ people suggested a link between people who wear glasses and cognitive function. The cause of the results were not studied. Maybe the same genes influence IQ and myopia. Maybe not.
Note that the study was limited to individuals of European descent, excluding people of other genetic backgrounds.
Other studies have established links between poor eyesight and cognitive function. In 1988, 5943 visually impaired and 8991 non-visually impaired men (all 18-years-old) were studied. The first group of short-sighted men had higher test scores and education levels.
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