How Has COVID-19 Changed the Epidemiology of Myopia?

October 15, 2021

By Joshua Foreman, PhD; Mohamed Dirani, PhD, MBA, GAICD; and Arief Tjitra Salim, BEng

Almost two years since the pandemic began, the protracted lockdowns still experienced by people in many jurisdictions around the world have taken an unquantified but likely severe toll on human health and well-being.

The emergence and rapid global spread of COVID-19 has resulted in dramatic and unprecedented changes to the way most of us live our lives, forcing us to adapt rapidly to an invisible and unpredictable threat in almost countless ways. Infection control measures, including stay-at-home orders and the closure of many sectors of the economy, have undoubtedly saved the lives of millions, and prevented permanent disability for even more, while ensuring that hospital systems avoid being overwhelmed.

However, almost two years since the pandemic began, the protracted lockdowns still experienced by people in many jurisdictions around the world have taken an unquantified but likely severe toll on human health and well-being. Of particular concern are the children and adolescents who, upon the closure of schools and public leisure centers, have been required to receive their education, to socialize, and to attempt to keep themselves entertained, all while remaining at home, with digital technology usually doing the heavy lifting in all three domains. Apart from the unsurprising impacts on children’s mental health,1,2 research has begun to show that these behaviors are producing a range of further detrimental health effects — including on the health of children’s eyes, with reports surfacing of a surge in what experts are calling “quarantine myopia.” Here we discuss what the scientific literature says about how COVID-19 has changed the epidemiology of myopia.

A Closer Look at Quarantine Myopia
The majority of research on myopia during the pandemic has taken place in China, with at least nine peer-reviewed studies having been published as of the start of October 2021. Among the most striking was a 6-year prospective cross-sectional study of almost 124,000 children aged 6-13 years which revealed that the spherical equivalent (SE) among the study’s youngest participants (aged 6 to 8 years) in the year 2020 was -0.28D to -0.32D more myopic than the average for the five years prior to the pandemic, and that the prevalence of myopia among 6-year-olds almost quadrupled (from 5.7% to 21.5%) from the highest pre-pandemic estimate.3 The prevalence jumped by almost 70% and 34% among 7- and 8-year-olds, respectively, compared to the highest pre-pandemic estimate, while older age groups were less significantly affected. 

Additional studies conducted in China provided further evidence for an explosion of cases of quarantine myopia, one of which followed a cohort of almost 30,000 primary and junior high school children at four six-monthly intervals in 2019 and 2020 and showed that, while the prevalence of myopia increased by 5% in the interval before the pandemic (as expected given the increasing prevalence with age), the interval between the second and third timepoints during lockdown saw a massive 21% spike, with a small reversal by approximately 5% when the lockdown ended.4

Another study followed over 1 million students aged 7-18 years from Zhejiang Province, and found that while the six-monthly increase in prevalence was only 1% and the six-monthly incidence was 8.5% immediately preceding the pandemic, the increase in myopia’s prevalence jumped to 5.5% and the incidence increased to 13.6% in the first six months of 2020, with a concomitant 50% increase in mean progression rate.5 These increases were statistically correlated with more time online and less time outdoors.

Similar results were reported in Chongqing, China, where, from 2019 to 2020, the prevalence of myopia increased by a staggering 23% among school kids to over 55%, while the mean SE decreased from -1.64D to -1.94D.6 The use of computers and tablets over televisions for online learning, as well as the duration and number of online classes, were all associated with more myopic SE. The central role played by digital screen time as a key risk factor for quarantine myopia was supported by further studies in China, where one group of researchers found that every additional hour of screen time was associated with a 26% higher risk that myopia would progress, with computers and smartphones being approximately twice as risky as televisions,7 and another reporting that increased digital screen time and online learning were associated with a 2.7 and 2.8-times higher risk of more myopic SE during home confinement.8

Similar Trends Around the World
Outside of China, the epidemiological picture is similarly grim. One small retrospective Turkish study of myopic children reported that, during the year 2020 in which participants engaged in home education, their mean progression rate was -0.71D, which was statistically significantly more rapid than the rates of -0.41D to -0.54D in the previous three pre-pandemic years.9 In this cohort, myopia progressed almost 50% faster among those who did not spend 2 hours outdoors per day compared to those who did. These findings were reflected further west along the Mediterranean, where more than one-third of young Spanish children aged 5-7 years significantly increased their near work and screen time from 2019 to 2020 and experienced a reduction in their mean SE from -0.66D to -0.48D.10

To date, only one small cross-sectional study from the United States has been published, which showed that myopic children spent significantly less time outdoors and engaged in less physical activity than their non-myopic counterparts, and that, compared to previous years, time engaged in digital screen time was significantly higher during 2020, thus increasing the risk of further myopic progression.11 

Concerningly, findings by Israeli clinicians may portend widespread failure of pharmacologic myopia control strategies, with children treated with low-dose atropine progressing at an average of -0.73D during one full year of lockdown, compared to just -0.33D during the previous year.12 These findings were echoed in South Korea, where both myopic progression and axial elongation rates were significantly higher after commencing home-based online learning than before for children treated with 0.05% and 0.025%, but not 0.01%, atropine.13

Concerns are Mounting Regarding Long-Term Eye Health
It is clear that a consensus is rapidly forming around the exacerbation of the myopia crisis by home confinement during the COVID-19 pandemic, with compelling evidence implicating excessive digital screen time and insufficient outdoor time in the increases seen in both incident and progressive myopia. Indeed, our recent systematic review and meta-analysis in The Lancet Digital Health demonstrated that high levels of exposure to mobile digital devices were associated with an almost 30% increased risk of myopia, and that this risk increased to 80% if computer screen time was included.14

It is still too early to know the full scope of this problem, but we anticipate that over the next several years there will be many more studies from all over the world that report similar findings, in addition to earlier ages of disease onset, all of which will increase the incidence of high myopia and the global burden of sight-threatening complications, such as myopic macular degeneration and glaucoma, for years to come.

Global efforts to eliminate avoidable vision impairment and blindness have been impressive in recent years, and the recent commitment by governments and international agencies such as the World Health Organization to prioritize addressing the global burden of refractive error instilled a sense of optimism that the world would tackle the problem of myopia head-on and that governments would implement strategies both for myopia control and the provision of refractive correction to all who need it. Sadly, the collateral damage of COVID-19 public health measures may include a reversal of much of this progress. The upsurge in the global burden of myopia resulting from this chaotic period will undoubtedly exert additional and unexpected pressure on the fight against avoidable vision loss, and it remains to be seen whether, after the dust settles, the global community will be willing and able to reverse some of the damage that has been done to our children’s eyes.

Joshua Foreman, PhD, is the head of research at Plano Pte Ltd, a technology company that develops solutions to manage excessive smart device use and myopia among children worldwide. He is also a research fellow both at the Department of Ophthalmology at the University of Melbourne and at the Centre for Eye Research Australia, where he consults for the World Health Organization. He is also a Visiting Scholar at the School of Global Public Health at New York University, and he holds an honorary position at the School of Public Health at the University of California, Berkeley.

Mohamed Dirani, PhD, MBA, GCAID, is the founding managing director of Plano Pte Ltd and an adjunct associate professor at the Duke-NUS Medical School. He is also an adjunct principal investigator at the Singapore Eye Research Institute and an Honorary Principal Investigator at the Centre for Eye Research Australia.

Arief Tjitra Salim, BEng, is the research and operations lead at Plano Pte Ltd.



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