Orthokeratology and myopia control: A comprehensive meta‐analysis of axial growth in children and adolescents

Aims/Purpose: The aim of this study was to evaluate the longitudinal effect on axial eye length in myopic children and adolescents treated with orthokeratology (OK) lenses compared to spectacles (GL), through a systematic review and meta‐analysisMethods: We conducted a systematic search of PubMed and Google Scholar databases for randomized controlled trials and cohort studies investigated the effects of longitudinal axial length difference, using the keyword “Axial Length” AND “orthokeratology” AND “spectacles”. From the initial 91 studies, we excluded 13 review studies, 10 meta‐analysis studies, 7 systematic reviews and 37 studies that did not meet the inclusion criteria. Of the 24 selected studies, detailed information was available at 24, 18, 12, 6, 3 and 1 month, with 10, 8, 19, 17, 2 and 3 studies respectively, allowing for the comparison between 2172 eyes treated with orthokeratology and 2095 eyes with glasses.Results: The analysis of the 24 studies (which included 59 comparisons from 1 month to 24 months) showed no statistically significant differences in initial axial length [AL(GL) = 24.39 ± 0.34 mm ; AL(OK) = 24.44 ± 0.38 mm] and initial refractive error [M(GL) = ‐2.59 ± 0.70 D ; M(OK) = ‐2.53 ± 0.44 D] between the two treatment groups (p > 0.565, independent samples t‐test) and for the evolution time intervals (p > 0.591, ANOVA). This analysis encompassed 4267 eyes with a mean age of 10.23 ± 1.21 years. Forest plot provided in an overall effect size of myopic defocus AL=‐0.16 com IC 95% ‐0.19 a ‐0.14, Z=12.71 p < 0.001. A random effects model was used considering the heterogeneity observed (I2=97%; p < 0.001, df=58). There was a greater myopia control effect at 24 months (AL=‐0.26, 95% IC ‐0.29 to ‐0.22, Z=13.71 p < 0.001; I2=0%; p = 0.95) than to treatments of less than 3 months (AL=‐0.04, 95% IC ‐0.06 to ‐0.01, Z=2.60 p = <0.009; I2=86%; p < 0.001).Conclusions: While the treatment at 24 months shows an homogeneous behaviour among studies, shorter follow‐up times renders a larger heterogeneity and for that reason, longer follow‐up periods should be preferred to estimate a more solid effect size. Orthokeratology treatment has been shown to be effective in myopia control progression for short or longer longitudinal treatments in children and young people with spectacles comparison.