Doctors are worried that the Covid-19 pandemic will cause more children to develop severe levels of nearsightedness in the future.
The Covid-19 virus itself does not cause nearsightedness. But because of the pandemic, two lifestyle factors have changed: 1) children are spending much less time outdoors, and 2) children are spending much more time looking at computers, tablets and smartphones. Both of these factors promote nearsightedness in children.
Studies show that a single hour of daily outdoor activity in children significantly reduces the risk of severe nearsightedness by as much as 45 percent. We do not know why this occurs, but the science is quite strong (multiple well-designed studies). This sunlight effect is not caused by, but rather is independent from, the other major factor, which is extensive close focusing. Children who use electronic devices for longer than six hours a day and have less than three hours of outdoor activity per week have twice the risk of developing nearsightedness. Each of these factors — sunlight and close viewing — independently affects the development of nearsightedness. So there is something about sunlight and something about prolonged close focusing in children that affects the development of the eyes to cause nearsightedness. Both factors together are additive.
Adults are not affected by these factors. But even people up until the age of 22-25 can be affected by a lack of sunlight exposure and extreme amounts of close focusing.
So get the children and young adults off the couch and outside for sunlight exposure and make sure they take breaks from the computer or TV to ease the amount of nearsightedness that they may develop. It is good for the eyes and probably for mental health as well.