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An increase in myopia progression was observed among Chicago-area children early in the COVID-19 pandemic, reported researchers, who suggested that closure of schools and cancelling of activities may have played a role.

In the overall cohort of over 2,000 children in this retrospective observational study, the change in mean spherical equivalent from 2020 to 2021 was 2.2 times greater than the change from 2019 to 2020 (0.42 D vs 0.19 D), reported Rebecca Mets-Halgrimson, MD, of the Ann & Robert H. Lurie Children's Hospital of Chicago and Northwestern University Feinberg School of Medicine, and colleagues in the .

In a subset analysis of patients who had a cycloplegic refraction in all 3 years of the study, there was a significant difference in myopic shift between years (F-ratio 14.4, P<0.00001), and a significant change from 2020 to 2021 (P=0.00008) but not from 2019 to 2020.

"This study confirms what other studies have found," Jeffrey J. Walline, OD, PhD, of the Ohio State University in Columbus, told MedPage Today. "The fact that the refractive error of the sample changes more than twice as much after the pandemic as it does before almost certainly indicates the pandemic affected the change in refractive error in children."

He explained that shifts in refractive error typically decrease as children age. The study findings suggest that "children became nearsighted earlier, and nearsighted children increased their myopia progression following the pandemic. These factors would lead to children requiring spectacle wear at earlier ages and more frequent changes in prescription for myopic children."

David Mackey, AO, of the University of Western Australia and the Lions Eye Institute in Perth, told MedPage Today that "most glasses are given in 0.25-D increments. So 0.42 is nearly two steps compared to 0.19, which is under one step. Many people might not bother changing glasses for a one-step increase but would be likely to for a two-step increase. So this increase in the rate of myopia progression would be noticeable for many on an individual level."

The study authors noted that multiple studies an increased myopia prevalence was associated with more schooling and higher levels of education. "A complex interplay among behaviors such as increased near work" -- reading, writing, watching television, and using other screens -- "without breaks and decreased time outdoors may explain the association between education and myopia," they wrote.

Ahmed Kassem, MD, of the Sanford South University Eye Center and Optical in Fargo, North Dakota, told MedPage Today that "the COVID-19 lockdown unfortunately represented the perfect storm for these two factors to simultaneously occur, with restrictions imposed on outdoor activities and switching to virtual classrooms."

However, as Walline noted, the study doesn't investigate near work or time outdoors, "so it provides no insight into the potential mechanism related to an increase in myopia progression."

It's difficult to understand the "true meaning" of the study due to its design, he added. "It includes some myopic and some non-myopic children, and each year contains a different sample with some children consistently represented throughout."

He also said that while the study authors concluded that the findings support reducing online learning and screen time, they don't measure screen time. "So, that is not a take-home message from this study."

Still, it's important for clinicians to understand the impact of screen time and near work on myopia progression, particularly in younger age groups, Kassem said. "This could also translate to consideration of myopia control approaches such as low-dose atropine, orthokeratology, and sooner in this age group."

But even treatment to slow myopia progression may not be able to fully reverse the effects of a pandemic. Mackey was a co-author of an of atropine eye drops for myopia. "When we compared the benefit of low concentration before, during, and after the lockdown period, there was less benefit of atropine in slowing myopia during lockdown. This was also seen in atropine studies in Europe and America," he said.

For this study, Mets-Halgrimson and colleagues included 2,064 patients ages 2-17 years with cycloplegic refractions in the months of January, February, or March in the years 2019, 2020, or 2021 at a tertiary children's hospital. The first 3 months of each year were chosen to reflect similar periods before the pandemic (2019 and 2020) and during it (2021).

The mean age of the study population was 9.6 in 2019, 9.9 in 2020, and 10.5 in 2021, and the mean spherical equivalents were 0.12 D in 2019, -0.07 D in 2020, and -0.49 D in 2021. In a subset of 109 patients who returned for evaluations in all 3 years, the mean spherical equivalents decreased from 0.66 D in 2019 to 0.51 D in 2020 and 0.22 D in 2021.

Looking at the prevalence of myopia grouped by age, 8-year-old and 17-year-old patients had the greatest increase compared with baseline. When grouped by refractive error, children with low myopia (-0.5 D to -3.00 D) showed the greatest change in mean spherical equivalents in 2020 to 2021.

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