Comparison of Clinical Efficacy of Different Adjustment Methods in Software-Assisted Orthokeratology Lens Fitting for Chinese Children: A Prospective Randomized Controlled Trial

Purpose To compare the clinical efficacy of three parameter-optimization strategies in software-assisted orthokeratology (ortho-k) lens fitting for Chinese children. Methods In this single-blind (participant-masked) prospective randomized controlled trial, 171 myopic children aged 8–15 years who were first-time ortho-k lens wearers (Menicon Z Night) were enrolled between October 2023 and October 2025 at Chongqing Aier Children's Eye Hospital and randomly allocated in a 1:1:1 ratio to three groups (n = 57 each). Group A (control) wore lenses prescribed directly by the fitting software without adjustment; Group B wore lenses prescribed with an over-correction of − 1.50 D; Group C wore lenses prescribed with − 1.50 D over-correction combined with a 40-µm increase in sagittal height and a 1° flattening of the tangential angle. The primary outcomes were uncorrected visual acuity (UCVA), axial length (AL), treatment zone diameter (TZD), and corneal safety over 12 months. Only the right eye of each participant was analyzed. Results All 171 participants completed the 12-month follow-up. Baseline characteristics (age, sex, spherical equivalent, and AL) were comparable among the three groups (all P ≥ 0.05). Fitting success rates were similar (Group A: 100.0%; Group B: 96.5%; Group C: 98.2%; P = 0.774, Fisher–Freeman–Halton exact test). At 1 month, mean LogMAR UCVA was 0.00 ± 0.02, 0.03 ± 0.08, and 0.02 ± 0.05 in Groups A, B, and C, respectively (P = 0.062), and lens centration was acceptable without significant intergroup differences (P = 0.373). TZD was significantly smaller in Group C than in Groups A and B at all visits (1 month: 2.65 ± 0.45 mm vs. 3.28 ± 0.44 mm and 3.16 ± 0.39 mm; all pairwise P < 0.001); TZD increased over time in Groups A and B but remained stable in Group C (mixed-effects model, group × time interaction: β = −0.026 mm/month, P = 0.007). Cumulative axial elongation at 12 months was 0.23 ± 0.15 mm (A), 0.21 ± 0.24 mm (B), and 0.13 ± 0.19 mm (C) (overall P = 0.013); Group C showed significantly less axial elongation than Group A (P < 0.001, LSD post-hoc test; adjusted difference − 0.11 mm, P = 0.008, ANCOVA). No serious adverse events occurred (Grade I corneal staining: 1, 0, and 2 eyes; P = 0.774). Conclusion Software-assisted ortho-k fitting achieved a high fitting success rate (98.2%) in Chinese children. Among the tested protocols, − 1.50 D over-correction combined with a 40-µm increase in sagittal height and a 1° flattening of the tangential angle produced a smaller and more stable treatment zone and significantly slower axial elongation over 12 months, without compromising visual outcomes or corneal safety. Trial registration Medical Research Registration and Filing System, National Health Security Information Platform of China (registration No. MR5026074835). Prospective registration was not required when enrolment began in 2023 the study was registered retrospectively through the platform's supplementary registration procedure. Running title Softwareassisted orthokeratology optimization in Chinese children. Word count Abstract ~ 280 Main text ~ 4,000.