Changes of Retinal Nerve Fiber Layer Thickness in Obstructive Sleep Apnea Syndrome: A Systematic Review and Meta-analysis

Abstract

ABSTRACTPurpose: Many studies have assessed the changes of retinal nerve fiber layer (RNFL) thickness in patients with obstructive sleep apnea syndrome (OSAS), but the results were inconsistent. Therefore, a meta-analysis was performed to evaluate the RNFL changes in OSAS measured in vivo.Methods: Pertinent studies were identified by a comprehensive search of PubMed, Embase, Web of science, Cochrane library, Scopus, and Chinese biomedical disc databases from inception to August 2016. A fixed effects model was used to pool the weighted mean difference (WMD) and 95% confidence interval (CI) between OSAS group and control group.Results: Seventeen studies were included in the final analysis, with 12 for descriptive analysis and 5 for meta-analysis, involving a total of 1757 eyes (1106 in the OSAS group and 651 in the control group). The RNFL in OSAS was significantly lower than control group, with pooled WMD −3.53 (95%CI: −4.80 to −2.26, P < 0.001) for average RNFL, −3.69 (95%CI:−5.49 to −1.89 P < 0.001) for superior RNFL, −4.66 (95%CI: −6.92 to −2.39, P < 0.001) for inferior RNFL, −3.15 (95%CI:−5.19 to −1.10, P = 0.003) for nasal RNFL, and −2.45 (95%CI: −4.59 to −0.31, P = 0.025) for temporal RNFL. Along with severities of OSAS, a trend of more profound reduction of average RNFL was observed in advanced OSAS, with WMD of average RNFL thickness −1.75 (95%CI:−4.47 to −0.98, P = 0.209) for mild OSAS, −3.54 (95%CI:−6.33 to −0.73, P = 0.013) for moderate OSAS, and −7.17 (95%CI:−10.00 to −4.34, P < 0.001) for severe OSAS. The majority of studies in the descriptive review demonstrated similar findings.Conclusion: The OSAS was associated with a reduced RNFL in all quadrants compared to controls. Evaluation of RNFL may serve as a tool for grading severities of OSAS. Considering the limited evidence, the conclusions should be interpreted cautiously.