ABSTRACT
CLINICAL RELEVANCE: Evaluating changes in refractive astigmatism after 'study at home' during the COVID pandemic may shed light on the aetiology of refractive errors. BACKGROUND: To investigate whether there has been a change in the proportion of astigmatism among primary school children after the school closure period during the COVID-19 pandemic. METHODS: This observational study compared cross-sectional (2018: n = 112; 2020: n = 173) and longitudinal data (n = 38) collected from two vision screenings, one in 2018 and the other after the school closure period in 2020, in the same primary school for children aged 8-10 years. Non-cycloplegic refraction and axial length were measured using an open-field auto-refractometer and IOL Master, respectively. A questionnaire focusing on demographic information, near-work time, and outdoor activities was administered to parents of all participants. RESULTS: While there were no significant differences in age, gender, or monthly family income between the two cohorts, astigmatism proportion (Cyl ≥ 0.75 D) in 2020 was 1.5-fold higher than that in 2018 (49.1% vs. 33.9%). The median cylindrical power was significantly higher in 2020 in older children (9 or 10 years old). More importantly, the children participating in both vision screenings had cylindrical power and J0 astigmatism significantly increased by 0.35 ± 0.40 D and 0.21 ± 0.25 D, respectively. CONCLUSION: A significant increase in astigmatism (both proportion and magnitude) was found after the school closure period. Further studies are needed to investigate the origin of this increased astigmatism.