Combined Small Treatment Zone Orthokeratology and Alternate-Day 0.01% Atropine for Axial Elongation Control in Rapidly Progressing Myopic Children.

Purpose: To evaluate the efficacy of small treatment zone (STZ) orthokeratology (ortho-K) combined with alternate-day 0.01% atropine to control axial elongation in rapidly progressing myopic children and identify associated optical predictors. Methods: This prospective randomized study included 105 children ages 8 to 12 years with axial elongation ≥0.20 mm during the initial 6 months of STZ ortho-K wear, assigned to ortho-K plus alternate-day 0.01% atropine (AOK) or ortho-K alone (OK) for 12 months. The primary outcome was axial length (AL) elongation. Other outcomes included pupil diameter (PD), intraocular pressure, visual quality, and adverse events. In the AOK group, corneal higher-order aberrations (HOAs) and pupil-zone defocus were assessed before and after atropine therapy. Results: AL elongation was lower in the AOK group than in the OK group at 3, 6, and 12 months (0.03 ± 0.06 vs. 0.09 ± 0.04; 0.09 ± 0.08 vs. 0.18 ± 0.07; and 0.20 ± 0.12 vs. 0.33 ± 0.09 mm, respectively; all P < 0.05). At 3 months, corneal HOAs and pupil-zone defocus increased in the AOK group (all P < 0.05). In AOK, multivariable regression identified baseline age, PD, and total pupil-zone defocus as independent predictors of 1-year AL elongation. Mild photophobia occurred in two participants, with no serious adverse events. Conclusions: Compared with STZ ortho-K alone, adding alternate-day 0.01% atropine further reduced axial elongation in rapidly progressing myopic children, with response associated with age and pupil-related optical factors, including PD and pupil-zone defocus. Translational Relevance: Optimized lens design and atropine dosing may support precision optical-pharmacologic myopia control.