Efficacy and Safety of Specialty-Designed Orthokeratology Lenses with a Reduced Corneal Central Zone Moulding Area in Children with Low Myopia: A Prospective, Randomised, Controlled Trial

Purpose: Orthokeratology (ortho-k) is widely used for myopia control in children. Specialty-designed ortho-k lenses with a modified corneal reshaping profile may offer an alternative approach for myopia control through altered lens design characteristics. This study aimed to evaluate the efficacy and safety of this lens design in slowing axial elongation and myopia progression in children with low myopia, and to explore ocular structural predictors of the treatment response. Methods: This prospective, randomised, double-masked clinical trial enroled 80 children aged 8–14 years with low myopia (−1.00 to −3.00 D). Participants were randomly assigned (1:1) to wear either standard-design ortho-k lenses or specialty-designed ortho-k lenses designed to produce a reduced corneal central zone moulding area for 12 months. Axial length was measured at baseline and at 1, 3, 6, 9 and 12 months. The primary outcome was the change in axial length (ΔAL) over time. Secondary outcomes included changes in spherical equivalent refraction (SER) and adverse events. Results: The mean base curve squared (BC2), representing the estimated corneal central zone moulding area, was 8.73 ± 5.59 mm2 in the test group, which was significantly smaller than that in the control group (11.21 ± 5.17 mm2;t = 2.685, p = 0.008). Compared with the control group, the values of ΔAL at month 6 (0.103 ± 0.14 vs. 0.047 ± 0.11, p = 0.01), month 9 (0.141 ± 0.16 vs. 0.060 ± 0.12, p = 0.002) and month 12 (0.168 ± 0.20 vs. 0.077 ± 0.14, p = 0.004) were significantly smaller. No significant difference in severe adverse events was observed between the two groups. Conclusion: Orthokeratology effectively slowed axial elongation in children with low myopia. Specialty-designed ortho-k lenses with altered corneal reshaping characteristics demonstrated greater inhibition of axial elongation. Trial registration: Chinese Clinical Trial Registry, ChiCTR2500113706, retrospectively registered on 2 December 2025.