The Association of Treatment Zone Decentration With Axial Length Elongation During 2 Years of Orthokeratology Treatment

OBJECTIVE: To investigate the association between treatment zone decentration and axial length elongation in myopic children during 2-year orthokeratology (Ortho-K) treatment. METHOD: This retrospective study analyzed clinical data from myopic children who underwent Ortho-K treatment. The magnitudes and direction of Ortho-K treatment zone decentration were recorded along with axial length measurement at baseline and 2-year follow-up. Right eye data were collected for statistical analysis. RESULTS: Sixty subjects were enrolled and divided into three groups according to the distance of treatment zone decentration: 12 eyes in the mild (<0.5 mm), 30 eyes in the moderate (0.5-1.0 mm), and 18 eyes in the severe decentration group (>1.0 mm). Axial length elongation was significantly slower in both severe (0.28 ± 0.21 mm) and moderate decentration group (0.36 ± 0.20 mm) compared with that of the mild decentration group (0.55 ± 0.24 mm) at 2-year follow-up (P < 0.05). Multivariate regression analysis showed that magnitudes of Ortho-K treatment zone decentration were associated with the axial length elongation (P = 0.013). CONCLUSION: Greater treatment zone decentration was associated with less axial length elongation. Moderate Ortho-K treatment zone decentration should be optimal choice for safety and efficiency of myopia control in myopic children.