Peripheral Defocus in Orthokeratology Myopia Correction: Systematic Review and Meta-Analysis.

This study aimed to assess the effect of peripheral defocus with orthokeratology lenses (PDOK) on myopia control in children and adolescents through a systematic review and meta-analysis. A comprehensive search was conducted in the PubMed and Web of Science databases to identify randomized controlled trials (RCTs) and cohort studies on PDOK, using the keywords "peripheral refraction" and "orthokeratology". Studies were included if they reported spherical equivalent (M) peripheral refraction at 25° and/or 30° with accompanying statistical data along the horizontal meridian before and after orthokeratology treatment. From the initial 133 studies, those excluded included nine non-English publications, 18 reviews, five meta-analyses, four systematic reviews, and 88 studies not meeting the inclusion criteria. Nine studies (three RCTs and six cohort studies) were included, involving 259 participants aged six to 30 years with a baseline refractive error of M = -2.44 ± 0.27 D, and treatment duration ranging from 14 days to 12 months. All the studies showed an increase in myopic defocus at 30° nasal (-2.55 ± 1.10 D) and temporal (-2.79 ± 0.75 D) eccentricities, averaging -2.67 ± 0.95 D across both. The overall induced myopic defocus was M = -2.56 D (95% CI: -2.21 to -2.91, Z = 14.33, < 0.001), according to forest plot analysis. Studies with treatment durations up to one year showed a higher myopic blur (M = -2.69 D, 95% CI: -2.48 to -2.89, Z = 25.93, < 0.001) compared to shorter treatments of less than three months (M = -2.39 D, 95% CI: -1.76 to -3.02, Z = 7.41, < 0.001). Orthokeratology lenses effectively induce myopic defocus at 30° eccentricity over both short- and long-term treatments in children and adolescents, suggesting potential benefits for myopia control in these age groups.