Effect of COVID-19 lockdown on refractive errors in Italian children aged 5-12 years: A multi-center retrospective study.

Purpose: to explore the potential consequences of the COVID-19 lockdown on the prevalence of myopia among Italian children aged 5-12 years.
Materials and Methods: retrospective multicenter study conducted in Italy. Population: children aged 5-12. Selection: random selection of children who received an eye exam between 2016 to 2021. Inclusion criteria: healthy children presenting for a routine eye exam. Exclusion criteria: presence of ocular comorbidities other than refractive error, such as blepharoptosis, media opacities, corneal or retinal dystrophies, strabismus, amblyopia, or concurrent therapy with atropine 0.01%. Outcome measure: age and spherical equivalent (SE) measured in diopters (D) in the right eye (RE) in cycloplegia. Statistical analysis: ANOVA test.
Results: total of 803 children. In the years prior to COVID-19, the mean SE ± SD of healthy age-school children was: 0.54 ± 1.49 D in 2016; 0.43 ± 1.84 D in 2017; 0.34 ± 1.41 D in 2018; 0.35 ± 1.75 D in 2019 (ANOVA, p = .659). In 2021, the mean SE changed to -0.08 ± 1.44 D (ANOVA, p = .005). Mean age was comparable in all groups (ANOVA, p = .307). The prevalence of myopes (SE ≤-0.5D) and hyperopes (SE ≥ 2D) was respectively 24.10% and 9.64% among children aged 60-96 months, and 63.86% and 6.02% among children aged 97-144 months. These values represent a statistically-significant increase in the number of myopes (Chi-square, p = .016) and decrease in the number of hyperopes (Chi-square, p = .001), as compared to previous years (.06 and.48 respectively).
Conclusion: this retrospective study shows a statistically-significant decrease in the mean SE in children aged 5-12 in the year following the COVID-19 lockdown. The percentage of myopes has increased significantly, while the percentage of hyperopes has decreased. The lifestyle changes caused by the lockdown led children to spend more time on near-work activities and digital devices, and less time outdoors. These are known risk factors for the development and progression of myopia. Studies in different countries are encouraged.