Myopia: The Evidence for Environmental Factors
Myopia: The Evidence for Environmental Factors
Singapore's "Go outdoors and play" campaign speaks to a growing acceptance that outdoor light is protective. Taiwan, on the other hand, has adopted a pharmacological response—the growing use of atropine, an agent that paralyzes eye muscles and dilates the pupil. Proponents defend its use as a means of slowing down the progression of myopia after it has been diagnosed in children, but the long-term effects of this treatment remain unknown.
For Chinese children, Morgan sees the education system as the real nemesis of good vision, because urging parents to get their kids outside will do no good if schoolwork continues to take priority over health. "The choice is between encouraging people to spend more time outdoors and mandating more time outdoors through the school system," Morgan says. "By and large Singapore has opted for persuasion, but all sorts of considerations suggest that making [outdoor time] part of the delivery of education may be more effective."
In touting sunlight exposure as a preventive measure, Morgan acknowledges a major issue that must be confronted, "namely that increasing time outdoors also has the potential to promote skin cancer—an issue which I am acutely aware of, as an Australian." (Australia and New Zealand have the world's highest incidence and mortality rates of cutaneous melanoma.) Here, he says, the mechanism becomes important. If protection is conferred by vitamin D, which is produced in the skin by ultraviolet light exposure—a hypothesis Mutti is pursuing—then myopia prevention would be incompatible with skin protection. But Morgan points to findings in chicks indicating that both daylight and intense ultraviolet-free indoor light conferred a protective effect. This, he says, suggests myopia prevention depends on visible light acting through the eye.
Although significant progress has been made so far, the importance of further clarifying the relationship between myopia and the environment is clear. "But even if successful prevention becomes possible, East Asia will still be faced for close to the next one hundred years, with an adult population at high risk of developing pathological myopia," Morgan says. "Further progress in our understanding of the natural history of pathological myopia is thus essential, and while there have been some promising developments in treatment, more effective treatments are still required."
Taking Action
Singapore's "Go outdoors and play" campaign speaks to a growing acceptance that outdoor light is protective. Taiwan, on the other hand, has adopted a pharmacological response—the growing use of atropine, an agent that paralyzes eye muscles and dilates the pupil. Proponents defend its use as a means of slowing down the progression of myopia after it has been diagnosed in children, but the long-term effects of this treatment remain unknown.
For Chinese children, Morgan sees the education system as the real nemesis of good vision, because urging parents to get their kids outside will do no good if schoolwork continues to take priority over health. "The choice is between encouraging people to spend more time outdoors and mandating more time outdoors through the school system," Morgan says. "By and large Singapore has opted for persuasion, but all sorts of considerations suggest that making [outdoor time] part of the delivery of education may be more effective."
In touting sunlight exposure as a preventive measure, Morgan acknowledges a major issue that must be confronted, "namely that increasing time outdoors also has the potential to promote skin cancer—an issue which I am acutely aware of, as an Australian." (Australia and New Zealand have the world's highest incidence and mortality rates of cutaneous melanoma.) Here, he says, the mechanism becomes important. If protection is conferred by vitamin D, which is produced in the skin by ultraviolet light exposure—a hypothesis Mutti is pursuing—then myopia prevention would be incompatible with skin protection. But Morgan points to findings in chicks indicating that both daylight and intense ultraviolet-free indoor light conferred a protective effect. This, he says, suggests myopia prevention depends on visible light acting through the eye.
Although significant progress has been made so far, the importance of further clarifying the relationship between myopia and the environment is clear. "But even if successful prevention becomes possible, East Asia will still be faced for close to the next one hundred years, with an adult population at high risk of developing pathological myopia," Morgan says. "Further progress in our understanding of the natural history of pathological myopia is thus essential, and while there have been some promising developments in treatment, more effective treatments are still required."
