Purpose : This study aimed to investigate whether lens design influences axial elongation when lenses are worn under appropriate fitting conditions. Methods : A total of 51 children (74 eyes), aged 6–12 years, were enrolled and followed for 12 months. Subject was diagnosed with myopia by subjective and cycloplegic refraction, and axial length was measured at baseline, 6 months, and 12 months. Participants were allocated to one of three OK lens designs (Lens A, B, or C) or single-vision spectacle lenses. Changes in axial length from baseline were analyzed between the OK and control groups, and stratified by age (6–8 years vs. 9–12 years). Intergroup comparisons were performed using one-way ANOVA and independent samples t-tests, with statistical significance set at p<0.05. Results : After 12 months, axial length elongation was significantly reduced in the OK group (0.1869 ± 0.2131 mm) compared with the control group (0.3553 ± 0.2160 mm; p=0.015). In the age-stratified analysis, younger OK lens wearers (6–8 years) exhibited a mean increase of 0.2284 ± 0.2293 mm, while older children (9–12 years) showed 0.0856 ± 0.1207 mm. In the control group, corresponding values were 0.4538 ± 0.1938 mm and 0.2849 ± 0.2160 mm, respectively. Across both groups, younger children demonstrated significantly greater axial length elongation than older children (p=0.03). By lens design, 12-month axial length elongation was 0.1619 ± 0.3028 mm for Lens A, 0.1892 ± 0.1591 mm for Lens B, and 0.2179 ± 0.1246 mm for Lens C, with no statistically significant inter-lens differences (p=0.089, p=0.197, p=0.599). Conclusion : Orthokeratology significantly inhibited axial length elongation compared with single-vision spectacles. Although younger children exhibited faster axial length growth than older children, OK lens wearers demonstrated a marked reduction across all age groups.