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Speaker: Understanding myopia boom can assist with developing interventions
Gene-environment mechanisms remain a research challenge.
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PHILADELPHIA – Understanding the factors that influence myopia development and its course are important to develop strategies to address the recent dramatic increase in myopia, particularly in Asian populations, Leslie Hyman, PhD, said in a presentation at the Wills Vision Research Center at Jefferson Symposium.
“Concerns about high myopia rates have led to a number of recent studies to document high-risk populations, to gain understanding of possible factors associated with onset and progression and to evaluate interventions to slow myopia progression,” she said.
Myopia is a multifactorial condition caused by the complex interaction of genetic and environmental factors, she said, and it has emerged as an important global public health problem, with the highest rates in Asian populations.
Current issues
The increase in myopia has been associated with comorbidities that increase the risk of severe vision loss, mainly in older adults, while pathologic myopia is a leading cause of visual impairment.
“In the U.S., at least 33% of adults are affected, with a 60% increase in U.S. prevalence in the past 30 years,” Hyman said. “Approximately $5.5 billion was estimated in direct medical costs in 2004 due to refractive error in U.S. adults 40 to 64 years old, an estimate that includes refractive eye examinations and corrective aids such as spectacles and contact lenses, but not refractive surgery.”
In the Asian population, myopia is at epidemic levels, with prevalence at 36% by age 9 in Singapore, Hyman said.
“Many large-scale population-based studies conducted worldwide over the past 30+ years document ethnic variation and an increase in prevalence over time, especially in Asian populations, which suggests strong environmental influence such as the protective effect of time spent outdoors,” she added.
Treatment and research
Varying degrees and durations of success have been seen with spectacle and contact lens treatment, as well as atropine use, Hyman said.
“Treatments aim to slow progression, but they do not slow eye growth or limit the physiological changes associated with axial elongation,” she said. “So, the risks for sight-threatening complications remain.”
One of the most important challenges in research are the gene-environment mechanisms, such as identifying whether genetic factors have a larger role in earlier onset myopia and environmental factors, Hyman said.
“For example, do near work or outdoor activity have a larger role with later onset myopia? What mechanisms might explain the role of time spent outdoors on myopia onset?” she asked. “There have been studies that have considered vitamin D, but nothing has seemed to explain that phenomenon yet. Why is the time spent outdoors associated with a decrease in myopia prevalence and incidence but not with progression? So, these are all open questions.”
Future
As the rapid rise in myopia prevalence indicates that environmental as well as genetic factors play an important role, prevention and slowing progression need to be better understood, Hyman said.
“We need to better understand the protective role of spending time outdoors,” she added. “We need to better understand subgroups, or identify those subgroups that may benefit from spectacle interventions, explore other novel therapeutic approaches and, from a public health perspective, it is important to develop strategies to address the high rate of visual impairment from uncorrected refractive error.
“We can decrease the rate of visual impairment by something as simple as just putting the right glasses on people’s faces worldwide,” she said. – by Kristie L. Kahl
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- Leslie Hyman, PhD, is a professor at Stony Brook University in Stony Brook, N.Y., and head of the Division of Epidemiology and Biostatistics in the Department of Family, Population and Preventive Medicine at Stony Brook Medicine. She can be reached at Leslie.Hyman@stonybrook.edu.
Disclosure: Hyman reports no relevant financial disclosures.