Development of Myopia in Children Linked to COVID-19 Pandemic

As a result of the COVID-19 pandemic and increased lockdowns, leading to increased use of online courses in education, there have been concerns on the impact on children of increased digital screen time worsening the global burden of myopia.

Xiao Yang, MD, PhD, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, and a team of investigators aimed to investigate changes in the development of myopia in young schoolchildren during the COVID-19 outbreak period in China.

In this study, results showed an increase in the development of myopia during the outbreak period in young schoolchildren, with the proportion of children at-risk of developing myopia also increasing during this time period.

Methods

Ahead of the present study, an ongoing prospective study was initiated in November 2018 to determine distributions and annual changes in refraction and axial length (AL) in schoolchildren.

Accordingly, this study analyzed a subset of the data to evaluate the association between environmental changes during the COVID-19 period and the development of myopia. Through November - December 2018, all grade 1 and 2 students from 12 primary schools in Guangzhou, China were enrolled, with follow-up exams performed annually.

Thus, the subjects were organized into the exposure group (n = 1572) which included students in grade 1 in November and December 2018 who were then assessed from grade 2 (November - December 2019) to grade 3 (November - December 2020) during the COVID-19 pandemic.

On the other hand, the non exposure group (n = 1472) consisted of students in grade 2 in November and December 2018 assessed from grade 2 (November - December 2018) to grade 3 (November - December 2019) in the period prior to the pandemic.

Each visit consisted of the evaluation of uncorrected visual acuity using the Early Treatment Diabetic Retinopathy study chart, accompanied by cycloplegic autorefraction performed using a desktop autorefractor.

In addition, investigators defined myopia as a spherical equivalent refraction (SER) of -0.50 D or less, with emmetropia defined as SER greater than -0.50 D and less than +2.00 D, and hyperopia defined as +2.00 D or greater.

Main outcomes in the study included changes in cycloplegic SER, axial length (AL) elongation, and myopia incidence from grade 2 to grade 3.

Results

Within the study, a total of 2679 eligible students were included in the analysis, with a mean age of 7.76 years and 1422 (53.1%) males.

Of that number, 1207 students were included in the exposure group examined in November and December 2019 and 1472 were in the non exposure group examined in November and December 2018.

Following 1 year, 2121 of the 2679 grade 2 students (79.2%) were reexamined, with 7 students reported receiving orthokeratology treatment and unsuccessful cycloplegic refraction, leaving 2114 students in grade 3. This included 1054 students in the exposure group and 1060 in the non-exposure group.

In grade 2 students, SER and prevalence of myopia were not different between the 2 groups, while the mean AL was 0.11 mm (95% CI, 0.05 - 0.16) shorter in the exposure group.

Then, data show from grade 2 to grade 3, students in the exposure group experienced a larger 0.36 D (95% CI, 0.32 - 0.41, P <.001) myopic shift of SER and 0.08 mm (95% CI, 0.06 - 0.10, P <.001) greater AL elongation, in comparison to the non-exposure group.

Further, the incidence of myopia was 7.9% (95% CI, 5.1 - 10.6, P <.001) higher in the exposure group, compared to the non-exposure group.

Additionally, the mean SER in grade 3 in the exposure group was 0.35 D (95% CI, 0.25 - 0.45) more myopic compared to the non-exposure group. The prevalence of myopia in grade 3 (n = 219 of 1054) was 7.5% higher (95% CI, 4.3 - 10.7) in the exposure group, compared to the non-exposure group (n = 141 of 1060).

Data also show the proportion of children without myopia and with SER greater than -0.50 D and less than or equal to +0.50 D increased from 31.1% (n = 286 of 919 students) to 49.0% (n = 409 of 835 students).

Conclusion

Investigators concluded the period of outbreak of COVID-19 showed accelerated development of myopia in young Chinese schoolchildren, as well as increasing the risk of developing myopia in children without myopia.

They noted their concern that the incidence of myopia may remain high, even after the COVID-19 pandemic outbreak period.

“Moreover, behavior changes, including reduced time outdoors and increased digital learning, may persist beyond the period of the pandemic, heightening the risk of a prolonged acceleration in the progression of myopia,” investigators wrote.

The study, “Rates of Myopia Development in Young Chinese Schoolchildren During the Outbreak of COVID-19,” was published online in JAMA Ophthalmology.