The incidence of near-sightedness (myopia) appears to be increasing. Could our modern lifestyle be responsible for this change? The Sydney Myopia Study of over two thousand schoolchildren suggests that our lifestyle may indeed play a role. In this investigation, participants underwent vision exams and answered questionnaires concerning the amount of time they spent doing near work (such as reading and drawing), mid-range activities (such as watching TV or using a desktop computer), and playing outdoors. Time spent outdoors was protective in preventing or reducing myopia.
Why would outdoor activities reduce the development of myopia? According to the myopia study, the type of outdoor activity did not seem to matter. Thus, time spent playing sports or strolling through the park were both protective. Since light intensity is greater outdoors than inside, perhaps the intensity of light makes a difference. The pupil of the eye constricts more at higher light intensities which reduces image blur. Outdoor light alters neurotransmitter levels in the retina. Thus, light stimulates dopamine release, and this chemical may change the way the eye grows. In addition, we look further into the distance when we are outside. Whatever the mechanisms, it may be best to stop reading this and other posts and head out into the sunshine.