Ocular Dimensional Changes After 12 Months of Orthokeratology and Single-Vision Spectacle Use: A Three-Dimensional Magnetic Resonance Imaging Study.

Abstract

Purpose: This study investigated the 12-month impact of orthokeratology (Ortho-K) treatment on eyeball dimensions using magnetic resonance imaging (MRI). Results were compared with single-vision spectacle wearers (SVS).

Patients and methods: A total of 70 Chinese schoolchildren (mean age: 8.31 ± 0.47 years) with myopia were assigned to Ortho-K (n = 45) and SVS (n = 25). Baseline spherical equivalent (SE), visual acuity (VA), and flat keratometry (FK) were measured. MRI was performed at baseline and at 12 months to measure three-dimensional ocular dimensions, including longitudinal axial length (LAL), horizontal width (HW), and vertical sagittal height (VSH). Standard slit-lamp examinations ensured ocular health at all follow-up visits.

Results: At 12 months, the Ortho-K group showed significant reductions in SE and FK (p < 0.001), whereas the SVS group exhibited a significant increase (p < 0.05). LAL was significantly shorter in the Ortho-K group compared to SVS (p < 0.05). Although individual HW and VSH did not reach independent significance, repeated measures analysis of variance confirmed significant between-group differences in global eyeball shape over 12 months (p < 0.05). Correlation analysis revealed a significant association between SE and LAL in the SVS group (p < 0.05). In the Ortho-K group, SE showed no significant correlation with ocular dimensional changes (p > 0.05). In contrast, FK in the Ortho-K group demonstrated significant correlations with all dimensional parameters (p < 0.05), a pattern not observed in the SVS group.

Conclusion: Findings indicate that myopic progression in the SVS group is primarily driven by axial elongation, whereas refractive changes in the Ortho-K group arise from corneal reshaping. Over 12 months, Ortho-K wear modifies ocular dimensions and inhibits AL elongation more significantly than SVS, providing a structural basis for controlling myopic progression.