Effectiveness of Low-Dose Atropine for Myopia Control in European Children: A Real-World Cohort Study

Purpose: To evaluate the real-world effectiveness of low-dose atropine in slowing myopia progression in European children and to contextualize axial elongation using an age- and race-adjusted epidemiological model. Methods: This retrospective, longitudinal cohort study included 76 children (mean age 8.7 ± 1.5 years) with myopia treated with atropine 0.01%, 0.025%, or 0.05% at a tertiary hospital in Madrid. Cycloplegic spherical equivalent (SE) and axial length (AL) were recorded at baseline and 12 months. Expected untreated AL elongation was estimated using a published meta-regression model. Observed and expected AL changes were compared using paired t-tests. Predictors of SE and AL progression were assessed using multiple linear regression including age, sex, baseline SE or AL, atropine concentration, adherence, ethnicity, and family history. Results: Mean SE progression was -0.08 ± 0.11 D per year, and mean AL elongation was 0.08 ± 0.23 mm per year. Expected untreated elongation was 0.36 ± 0.09 mm per year and significantly exceeded the observed elongation (p < 0.001), representing a 78% relative reduction (effect size Cohen's d = -1.18). Older age (≥9 years) and more negative baseline SE were associated with greater SE progression (p < 0.05). Adverse effects and treatment tolerability were not systematically evaluated in this retrospective cohort. No significant differences were found across atropine concentrations, adherence levels, sex, ethnicity, or family history. The regression model for AL progression was not statistically significant. Conclusions: Low-dose atropine demonstrated real-world effectiveness in reducing myopia progression in European children. Axial elongation was markedly lower than epidemiological expectations, supporting low-dose atropine as a first-line therapy in routine clinical practice. Age and baseline refractive error were significant predictors of treatment response.