Change in Corneo-Scleral Thickness of Myopic Children Wearing Overnight Orthokeratology: 6 Months Follow-Up Study

Purpose: To explore changes in corneoscleral thickness among myopic children undergoing overnight orthokeratology (Ortho-k) and assess potential associations with axial elongation. Methods: This prospective study included myopic children receiving Ortho-k lens treatment with regular follow-ups in 6 months. Corneo-scleral cross-sectional images were obtained using a SPECTRALIS optical coherence tomography device. Measurements of anterior scleral thickness were taken at nasal (SS-N), temporal scleral spur (SS-T), and 1 mm away from these locations (SS-N1 and SS-T1). Results: A total of 24 children (38 eyes) with a mean age of 10.3±2.2 years were included. The mean thickness was 643±48.0 μm at SS-T, 611±50.7 μm at SS-N, 515±44.6 μm at SS-T1, and 506±37.5 μm at SS-N1. Boys exhibited significantly greater scleral thickness at SS-N1 and SS-T1 compared with girls ( P =0.01). After 6 months of Ortho-k use, significant thinning was observed at SS-T (from 643±48.0 μm to 616±44.0 μm; P =0.001) and SS-N (from 611±50.7 μm to 593±54.8 μm; P =0.015) compared with baseline values. However, the scleral thickness at 1 mm from the SS remained stable. No significant correlation was found between axial elongation and scleral thickness. A subgroup of monocular Ortho-k wearers found that SS-T and SS-N values decreased in eyes with monocular lens-wearing but remained stable in the untreated eyes. Conclusions: A significant reduction in corneo-scleral thickness was observed after six months of Ortho-k lens wear. These changes warrant further investigation to confirm their implications and underlying mechanisms.