We could say that eyeglasses are like bookends when they relate to economic growth.
Our story starts during the 13th century. Before the spread of eyeglasses, the work life of skilled craftsmen usually ended when they could no longer see close objects clearly–usually at 40 or so. Scribes, metalworkers, toolmakers, all could have worked another 20 years if they could just see better. According to economic historian David Landes, in Italy, when lens making became sufficiently proficient during the mid-15th century, the work life of craftsmen expanded and new techniques that required eyeglasses were invented.
Our story continues during 2004 with a free eyeglass program in rural northwestern China. When elementary school children whose families could not afford glasses got them for the first time, their grades improved. One third of the families in the study, though, refused the glasses.
This finally takes us to a story in The Economist about new eyeglass technology. Requiring no examination, people in developing nations will soon have access to $20 eyeglasses made with a silicone fluid that corrects the wearer’s vision with a self-adjusting lens.
And that returns us to eyeglasses and bookends. If more children in developing nations wear the new eyeglasses and more workers do also, at the beginning of one’s work life when human capital is developed and at the end when eyesight diminishes, eyeglasses will support economic growth.
I especially enjoyed reading about the invention and spread of eyeglasses and other early inventions that today we take for granted in The Wealth and Poverty of Nations (Chapter 4) and hearing about the free eyeglass program in this Freakonomics podcast. More academic but interesting, this article specifically presents the design and impact of the eyeglass study.