To the Editor.
—I read with interest the article by Sperduto et al in the March 1983 Archives (101:405-407) on the prevalence of myopia in the United States; however, I think there may be other conclusions that may be drawn from the data. The fact that there is an association of myopia with higher income and educational levels does not necessarily imply a causeand-effect relationship. I believe that an equally acceptable proposal is that certain work habits, intelligence, and myopia are genetically determined, resulting in better performance in school, more advanced education, and higher income as a result.My own clinical experience indicates two groups of myopes; the larger group consists of people whose myopia begins between the ages of 9 and 12 years, progresses for several years, then levels off in the middle to late teens, thereafter remaining constant indefinitely. In this group there seems to be a strong