The Japanese city of Kariya went as far as banning smartphone use for elementary and junior high school students after 9 p.m. starting last month, partly to reduce the strain on their eyes, according to The Japan Times.
In the U.S., eye doctors at the University of California, Berkeley, founded a specialized clinic to combat the rise in myopia among children. Dr. Maria Liu, head of the Myopia Control Clinic that opened last year, explained that prevention and treatment success depend on early detection. Nearsighted children under 10 could benefit the most from intervention. This age group is also the most susceptible to eye damage from prolonged use of visual media, according to the myopia specialist.
"The eyeballs are very adaptive while they are developing," Liu told me. "If we impose a lot of near work on the eyes as they are developing, the eyes will interpret nearsightedness as being the normal state."
Computers, tablets, and video games require specialized motor skills that young eyes have yet to develop. Mature, completely formed eyes have a better ability to cope with the visual stress from such devices.
"The earlier the onset of myopia, the later it tends to stabilize (once the growth process is complete), and the faster the progression," Liu said. Some children with myopia advance as fast as one or two diopters (the unit used to measure a lens’s optical power) per year, according to the specialist.
She explained the rise in myopia prevalence is likely caused by a shift in lifestyle from spending time outdoors to an indoor-oriented existence. Electronic devices play a major role in this shift, especially with young children being introduced to technology at an earlier stage in their life, and using handheld devices that require a smaller working distance than that for a physical book or television.
Although myopia rates are relatively low in agricultural regions and nations, the difference is most likely associated with academic work and near work demands, and has less to do with outdoor light intensity. "The higher the academic stress, the higher the prevalence and the earlier the onset of myopia," Liu said, noting there are differences even between school districts in the same city. If spending a certain amount of time outdoors had a significant effect on myopia, we should see prevalence rates vary geographically based on light intensity, she said.
Both genetic and environmental influences determine the early onset and the progression of myopia, but genetic studies have a hard time showing which inherited factors play a greater role: the parents' genes, their lifestyle, or both, according to Liu, who performs animal studies related to myopia.
When myopia debuts early, it has time to develop into something more severe, Liu explained. In pathological myopia, which is still relatively rare, the excessive elongation of the eyeball significantly increases the risk for retinal detachment, abnormal blood vessel growth, and other complications, which can lead to irreversible vision loss.