Efficacy and Safety of Different Atropine Regimens for the Treatment of Myopia in Children: Three-Year Results of the MOSAIC Randomized Clinical Trial

Importance: Additional data are required regarding atropine treatment regimens for control of myopia progression. Objective: To investigate the efficacy and safety of different atropine regimens for myopia in children. Design, Setting, and Participants: This was a secondary analysis of the 3-year results of the 24-Month Myopia Outcome Study of Atropine in Children (MOSAIC) trial, called the MOSAIC2 trial. The MOSAIC trial was an investigator-led, double-masked, randomized clinical trial of different atropine concentrations and regimens. The MOSAIC2 study took place at the Centre for Eye Research Ireland, in Dublin, Ireland, and included children and adolescents with myopia from the MOSAIC trial. Data analysis was conducted from November 2023 to February 2024. Interventions: Participants were randomly assigned to the following cohorts: group 1, nightly placebo for 2 years then 0.05% atropine eye drops for 1 year and group 2, nightly 0.01% atropine eye drops for 2 years then rerandomization to placebo nightly, tapering placebo, or tapering of 0.01% atropine eye drops for 1 year. Main Outcomes and Measures: Observed changes in cycloplegic spherical equivalent refraction and axial length from month 24, or baseline, to month 36. Results: A total of 199 children with myopia (mean [SD] age, 13.9 [2.4] years; 121 female [60.8%]) of the 250 children and adolescents from the MOSAIC trial were included in the MOSAIC2 trial analysis. Of 83 participants assigned to group 1, 66 (79.5%) reconsented to year 3, and 61 (73.5%) completed the trial. Of 167 participants assigned to group 2, 133 (79.6%) continued to year 3, and 121 (72.5%) completed the trial (0.01% atropine, then nightly placebo: n = 31 and n = 29 [93.5%]; 0.01% atropine, then tapering placebo: n = 29 and n = 25 [86.2%]; 0.01% atropine then tapering 0.01% atropine: n = 73 and n = 67 [91.8%], respectively). Compared with the group taking placebo then 0.05% atropine, the combined atropine then placebo groups had more spherical equivalent progression (adjusted difference, -0.13 diopters [D]; 95% CI, -0.22 to -0.04 D; P =.01) and axial elongation (adjusted difference, 0.06 mm; 95% CI, 0.02-0.09 mm; P =.008), and the group taking 0.01% atropine then tapering 0.01% atropine had more axial elongation (adjusted difference, 0.04 mm; 95% CI, 0.009-0.07 mm; P =.04). In the group taking placebo then 0.05% atropine, 15% (n = 10) and 8% (n = 5) reported blurred near vision and photophobia, respectively, during year 3, compared with 3% (n = 2) and 0%, respectively, in the group taking 0.01% atropine then tapering 0.01% atropine, and no reports in both placebo groups. Conclusions and Relevance: Despite more adverse events, participants using 0.05% atropine during year 3 had no differences in treatment completion rates and exhibited 0.13-D less myopia progression and 0.06-mm less axial elongation, compared with participants using placebo, supporting consideration of treatment as given to the group taking 0.05% atropine in this European population.