According to the findings of a population-based study conducted by the Chinese University of Hong Kong, unprecedented quarantine and social distancing measures imposed during the coronavirus disease 2019 (COVID-19) pandemic led in a “myopia explosion” in school-aged children in Hong Kong (CUHK).
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During the COVID-19 pandemic, schoolchildren saw a
2.5-fold rise in myopia incidence, as well as rapid myopia progression.
The Hong Kong Children Eye Investigation provided two
cohorts for this observational study (HKCES). The COVID-19 cohort (n=709; mean
age, 7.25 years) was recruited during a period of school closures and social
activity limitations, with an 8-month follow-up. The COVID-19 pre–cohort
(n=1,084; mean age, 7.29 years) was recruited before the epidemic and followed
for three years.
The COVID-19 group had a 2.5-fold greater yearly
incidence rate of myopia than the pre–COVID-19 cohort, at 29.68 percent vs.
11.63 percent.
Furthermore, during the epidemic, myopia progression
was nearly two times higher. The COVID-19 group had an estimated yearly change
in spherical equivalent refraction (SER) of -0.80 D, compared to -0.41 D in the
pre–COVID-19 cohort, and an estimated annual change in axial length (AL) of
0.45 mm vs 0.28 mm. During the pandemic, both AL elongation and SER alterations
predicted quicker myopia progression.
“It should be noted that -6.0 D is considered high myopia, which can lead to glaucoma, macular degeneration, and retinal
detachment,” said researcher Professor Calvin Pang of the Department of
Ophthalmology and Visual Sciences at the Chinese University of Hong Kong.
The experts noted, “Another concerning finding was the
considerable changes in children's lifestyle during the COVID-19 epidemic, with
a 68 percent decrease in outdoor time and a 2.8-fold rise in screen time.”
“During the epidemic, schoolchildren spent an average
of 7 hours indoors but just 24 minutes outdoors per day, compared to 2.5 hours
indoors and 75 minutes outdoors per day before the pandemic,” they wrote.
The research speculated that childhood myopia as a
result of the COVID-19 pandemic could be a major public health problem, given
Hong Kong’s high prevalence of myopia, which affects more than 40% of children
under the age of eight.
“The concern about a myopia epidemic in children
during the COVID-19 pandemic hits particularly close to home, as Hong Kong is
one of the world’s most densely populated cities, with the overwhelming
majority of the population living in urban areas, where outdoor spaces are
scarce,” said Professor Clement Tham of the CUHK Department of Ophthalmology
and Visual Sciences.
“Under these conditions, pupils spend substantially
less time outside and significantly more time near employment. These two
behaviors are linked to the development and progression of myopia,” according
to Tham.
“Increasing outdoor time to 2 hours per day or 14
hours per week is recommended for youngsters to prevent myopia progression.
Educators and parents should assist youngsters adopt healthy digital device
habits, such as taking a 30-second break after 30 minutes of staring at a
screen, according to Dr. Jason Yam of the CUHK Department of Ophthalmology and
Visual Sciences. “Finally, in high-risk children, effective myopia control
through pharmaceutical or optical therapies should be implemented.”
Source: Br J Ophthalmol
2021;doi:10.1136/bjophthalmol-2021-319307