Myopia is common and its prevalence is increasing (for example, myopia prevalence, monitored in nearly 1 million people who were joining the Israeli army at the age of 18, increased from 20% in 1990 to 28% in 2002)5. The economic burden is huge, estimated at around 260 billion dollars annually worldwide.6
The main influence on myopia progression is genetics.7More than 20 genetic loci for myopia are known and a child whose parents are both myopic has six times the risk for myopia than a child with non-myopic parents.
It has recently been explored how time spent outdoors is firmly associated with less myopic refraction. A study from China showed that the prevalence of myopia significantly decreased, from 39% (control group) to 30%, in schoolchildren who had 40 minutes of outdoor activities every day.8
There are many studies showing a definite relation between near work and myopia progression. A meta-analysis of 27 such studies (25,025 children) showed that myopia increased by 2% for every hour of near work per week.9