Global perspectives on childhood myopia: addressing the rising epidemic
Scientists from around the world gathered recently in Seattle, Washington, at the annual meeting of the Association for Research in Vision and Ophthalmology (ARVO) to address the global increase in myopia. Myopia rates, especially among children, have spiked dramatically over the past few decades. The National Eye Institute (NEI) organized the meeting to facilitate international collaborations aimed at understanding what’s driving the epidemic and how to control it.
Despite major research investments, the interplay between genetic and environmental influences, such as near work, outdoor light, and electronic device usage, remains unclear, according to NEI Director Michael F. Chiang, M.D. Chiang cited data that the COVID-19 pandemic exacerbated myopia rates, and that high myopia could affect nearly 1 billion people worldwide by 2050.
“School-based vision programs are crucial for early detection and correction of myopia,” said Chiang, noting that uncorrected refractive error is a significant cause of vision loss in the United States, particularly among disadvantaged groups. “Research advances stand to make a big impact on those who need it the most.”
Myopia epidemic has hit hardest in Asia
The myopia epidemic has hit hardest in Asia. In China, the prevalence among 15–19-year-olds is now 68.9%, with 9.9% having high myopia, said Seang Mei-Saw, Ph.D., National University of Singapore. Rates in China, Korea and Taiwan are all higher when compared with Europe, the U.S. and the Middle East.
“There’s a clear generational difference, with younger populations exhibiting higher rates of myopia,” said Mei-Saw. This increase, according to her, is largely due to kids’ spending more time in front of screens and less time outdoors. Mei-Saw mentioned a study with evidence that supports time outdoors as both a tool to prevent myopia and to control its progression. Researchers found that an average of two hours per day with outdoor light exposure at school can reduce myopia incidence by 63.7%. (Ho, 2019)
Significant increase in axial length over the past century
Myopia rates outside of Asia are lower, but no less a cause for concern, according to Caroline Klaver, M.D., Ph.D., Erasmus University Medical Center, Netherlands. More than half of all Dutch residents are myopic, according to long-term Dutch population studies such as Generation R2 (Jaddoe, 2017), which have revealed a significant increase in axial length over the past century. Dutch studies, said Klaver, are applicable globally, as they reveal universal risk factors and effective intervention strategies that might be adapted locally.
A clear concentration-dependent response to atropine with continuous treatment proving more effective than intermittent use was observed in studies from the Chinese University of Hong Kong. Atropine is one of the most studied and used drugs to prevent and control myopia. “Low-concentration atropine (0.05%) emerged as optimal for controlling myopia progression over five years, although long-term efficacy and safety continue to be studied,” said Helen Zhang, Ph.D., Chinese University of Hong Kong, presenting on behalf of Jason Yam Cheuk-sing, Ph.D. (Yam, 2020)
Other methods to prevent and control myopia include the use of special night lenses that reshape the cornea for a short period of time, “tricking” the eye into slowing the progression of myopia (orthokeratology), or lenses that adjust the focus of light on the peripheral retina when used daily, also slowing myopia progression (multifocal lenses). (Xu, 2023), (Walline, 2020)
Light therapy: promising treatment for myopia
Light therapy is a relatively new and promising treatment for myopia. It typically involves regular sessions where children are exposed to light for a specified length of time. These sessions can be conducted at home or in a clinical setting using specialized devices. High-intensity and red light therapies have been shown to influence eye growth and myopia progression. Studies indicate that high-intensity light reduces myopia in animal models and children, while red light therapy shows promise in controlling axial elongation (Dong, 2022). High-intensity light focuses on the brightness and mimicking natural sunlight intensity (over 10,000 lux), while red light focuses on a specific wavelength (around 650 nm) regardless of overall brightness.
“Red light therapy has shown excellent efficacy in controlling axial elongation and myopia progression in children; however, we must carefully assess its safety, as continuous exposure to high-intensity light could pose risks to the retina,” said Lisa Ostrin, O.D., Ph.D., a specialist in myopia and circadian rhythms from the University of Houston. She said that wearable technology now enables precise monitoring of light exposure that can help refine recommendations for preventing and controlling myopia. (Li, 2023)
After the experts’ presentations, discussion was guided in part by the launch of a consensus study by the National Academy of Science, Engineering, and Medicine (NASEM), on myopia pathogenesis and its rising incidence (National Academies of Sciences, 2024). The study aims to assess the current understanding of the mechanisms underlying myopia development and identify factors contributing to its increasing prevalence worldwide. The goals include identifying knowledge gaps, barriers to progress, and developing a research agenda to address these challenges.
Panel experts and the audience agreed that international collaboration on myopia research has become increasingly vital, a fact most recently acknowledge by the World Health Organization’s efforts to include refractive error coverage in universal health coverage metrics. These efforts will be further synergized by recommendations of a NASEM-led committee of scientists working on pathogenies of myopia.
Source: National Eye Institute (NEI)
References
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9- National Academies of Sciences, Engineering, and Medicine. 2024. The Rise in Myopia: Exploring Possible Contributors and Investigating Screening Practices, Policies, and Programs: Proceedings of a Workshop—in Brief. Washington, DC: The National Academies Press. https://doi.org/10.17226/27735