Abstract / Summary
Abstract Purpose To investigate the influence of treatment zone size and decentration on myopia progression and anisometropia changes in monocularly myopic children fitted with orthokeratology (OK) lenses. Methods This retrospective study included 78 monocularly myopic children (aged 8–16 years) fitted with OK lenses. Spherical equivalent refraction (SE) ranged from − 4.00 D to − 0.75 D in myopic eyes and − 0.50 D to + 0.75 D in fellow eyes. Corneal topography at 3 months quantified treatment zone (TZ) area and decentration. Participants were dichotomised by mean TZ area into Small TZ (≤ 9.82 mm², n = 40) and Large TZ (> 9.82 mm², n = 38) groups. Axial length (AL) changes and interocular AL difference were compared over 12 months using independent-samples t-tests and linear regression. Results At 1 year, the Small TZ group showed less myopic AL elongation than the Large TZ group (0.07 ± 0.15 vs. 0.19 ± 0.20 mm/year, t = − 3.002, P = .004), with no intergroup difference in fellow eye AL elongation (0.39 ± 0.27 vs. 0.37 ± 0.19 mm/year, P = .715). The reduction in interocular AL difference was greater in the Small TZ group (–0.32 ± 0.25 vs. − 0.19 ± 0.18 mm/year, t = − 2.746, P = .008). Regression analysis showed that myopic AL elongation (Y₁) correlated with TZ area (Y₁ = 0.025X₁ – 0.112, R² = 0.077, P = .014), but not with decentration. The change in interocular AL difference (Y₂) correlated with TZ area (Y₂ = 0.040X₁ – 0.644, R² = 0.127, P < .001) and myopic pupil diameter (Y₂ = − 0.11X₂ + 0.333, R² = 0.211, P < .001). Conclusions OK lens wear effectively reduces anisometropia in monocularly myopic children. Smaller TZ area and larger pupil diameter are associated with greater anisometropia reduction.