Abstract
BACKGROUND: The objective of this study was to evaluate the association of the presence of conjunctival ultraviolet autofluorescence (CUVAF) with the level and progression of myopia and the impact of reduced sunlight exposure during the COVID-19 pandemic confinement (PC). METHODS: A retrospective observational study was carried out using three cohorts, children (9-17 years old), young adults (18-25 years old), and adults (>40 years old) with myopia (≤0.75D) and at least three annual eye examinations (before and after PC). All participants underwent an automatic objective refraction and CUVAF area analysis. All the participants filled out a questionnaire regarding lifestyle and myopia history. RESULTS: The 298 recruited participants showed that during the PC, children's and young adults' myopia progression rate increased on average by -0.50 and -0.30 D/year, respectively, compared with the pre-pandemic level (p < 0.0001 and p < 0.01). A significantly greater progression was observed in those with low baseline myopia compared to those with moderate or high myopia (p < 0.01). CUVAF shows its protective effect associated with outdoor activity (OA) with regard to the age of onset of myopia and mean diopters (p < 0.01). In fact, although there were no differences in the increase in diopters between children with and without CUVAF during the PC, those who had CUVAF started with lower gains (-0.3 D/year) compared to those who did not (-0.5 D/year; p < 0.05). The myopia treatments (atropine drops, Ortho-K, and MiSight(®) contact lenses) showed a reduction effect in myopic progression rate post-PC in comparison with non-treated children (p < 0.0001, p < 0.0001 and p < 0.01, respectively). CONCLUSIONS: The strict restriction of OA during PC led to the rate of myopia progression doubling among children and young adults. This progression occurred mainly in children with previously low myopia, and CUVAF, as a biomarker of OA, reflects its potential to provide benefits in the form of recommended behavioral changes to protect against the development of myopia.