How Orthokeratology Affects Accommodative Response and Binocular Vision: A Systematic Review and Meta-Analysis

PURPOSE: Orthokeratology (OK) has been recognized as an effective intervention for slowing myopia progression. However, its effects on the accommodative response and its role in myopia control remain controversial. This systematic review and meta-analysis aimed to provide a comprehensive evaluation of the OK influence on accommodation. METHODS: Cochrane, Embase, and PubMed were searched for studies published up to April, 2024. All eligible studies that compared OK with a neutral control and reported measurements related to accommodative response in myopic patients were included. The outcomes evaluated were accommodation lag (AL), positive relative accommodation, and accommodation amplitude (AA). The mean difference [MD] and 95% confidence interval were used for continuous outcomes. Heterogeneity was assessed using I 2 statistics. The analysis was performed using R software version 4.4.1. RESULTS: A total of 14 studies comprising 1,404 patients met the inclusion criteria. Single vision spectacles was the control group in 12 articles, soft single vision contact lenses in one, and no intervention in one. The OK group showed a significant reduction in AL compared with control groups at 3 months follow-up (MD: -0.38D; confidence interval [CI]: -0.54 to -0.22D; P <0.00001; I 2 =0%). At 12 months, OK significantly increased AA compared with controls (MD: 0.64D; CI: 0.25 to 1.03D; P =0.001; I 2 =69%), which was not observed at 3 months (MD: 0.26D; CI: -0.16 to 0.70D; P =0.21; I 2 =80%). Positive relative accommodation did not differ significantly at 3 months (MD: -0.53D; CI: -1.08 to 0.02D; P =0.06; I 2 =83%). CONCLUSION: This meta-analysis demonstrates that OK significantly reduces AL and, in the long-term, increases AA compared with controls. These findings suggest that OK does improve the accommodation response, which may contribute to one of the mechanisms underlying its effectiveness in slowing myopia progression.