Myopia outcome study of atropine in children: Two-year result of daily 0.01% atropine in a European population

Purpose: The Myopia Outcome Study of Atropine in Children (MOSAIC) is an investigator-led, double-masked, randomized controlled trial investigating the efficacy and safety of 0.01% atropine eye drops for managing myopia progression in a predominantly White, European population. Methods: Children aged 6–16 years with myopia were randomly allocated 2:1 to nightly 0.01% atropine or placebo eye drops in both eyes for 2 years. The primary outcome was cycloplegic spherical equivalent (SE) progression at 24 months. Secondary outcomes included axial length (AL) change, safety and acceptability. Linear mixed models with random intercepts were used for statistical analyses. Results: Of 250 participants enrolled, 204 (81.6%) completed the 24-month visit (136 (81.4%) treatment, 68 (81.9%) placebo). Baseline characteristics, drop-out and adverse event rates were similar between treatment and control groups. At 24 months, SE change was not significantly different between 0.01% atropine and placebo groups (effect = 0.10 D, p = 0.07), but AL growth was lower in the 0.01% atropine group, compared to the placebo group (−0.07 mm, p = 0.007). Significant treatment effects on SE (0.14 D, p = 0.049) and AL (−0.11 mm, p = 0.002) were observed in children of White, but not non-White (SE = 0.05 D, p = 0.89; AL = 0.008 mm, p = 0.93), ethnicity at 24 months. A larger treatment effect was observed in subjects least affected by COVID-19 restrictions (SE difference = 0.37 D, p = 0.005; AL difference = −0.17 mm, p = 0.001). Conclusions: Atropine 0.01% was safe, well-tolerated and effective in slowing axial elongation in this European population. Treatment efficacy varied by ethnicity and eye colour, and potentially by degree of COVID-19 public health restriction exposure during trial participation.