Abstract
PURPOSE: To evaluate the impact of lockdowns during COVID-19 pandemic on manifest refraction in a young adult population. METHODS: A retrospective, observational study of flight academy candidates evaluated between 2019 and 2023. Data collected included demographics, best corrected visual acuity, and manifest refraction. The cohort was divided into three groups with respect to the COVID-19 lockdown periods. RESULTS: The study included 7,491 individuals with a mean age of 17.36 years (range 16-18), of whom 81% were male. Comparing refractive errors between the three groups, the highest rate of emmetropia, hyperopia and myopia were observed in the post-lockdown, during-lockdown group and pre-lockdown groups, respectively. Spherical equivalent (SE) significantly increased (a positive increase, indicating less myopia or more hyperopia) when comparing pre-lockdowns and during-lockdowns (mean difference = 0.100, p = 0.002), and between pre-lockdowns and post-lockdowns (mean difference = 0.119, p < 0.001). Multivariate regression analysis showed that both during-lockdowns and post-lockdowns periods were significantly associated with a positive shift in SE compared to the pre-lockdowns period (p = 0.005 and p = 0.001, respectively). Male gender was also a significant predictor for this hyperopic shift (p < 0.001). CONCLUSION: No increase in myopia was observed in healthy young adults, despite long periods of lockdowns and homeschooling during the Covid-19 pandemic.