title: Obstructive Sleep Apnea and Retinal Nerve Fiber Layer Thickness: A Meta-analysis.
abstract: OBJECTIVE
  The association between obstructive sleep apnea syndrome (OSAS) and retinal nerve fiber layer (RNFL) thickness has been examined in many studies. However, the findings are inconsistent. Our goal is to evaluate the association between OSAS and RNFL thickness by performing a meta-analysis.
  
  
  METHODS
  We conducted a PubMed database search in November 2014 to identify studies on OSAS and RNFL. Reference lists of retrieved articles were also reviewed. A fixed-effects model was used to compute the summary mean difference (MD).
  
  
  RESULTS
  Six studies involving 1034 eyes were included in the meta-analysis. The overall combined MD of RNFL in OSAS patients compared with control participants was -2.03 µm [95% confidence interval (CI), -3.67 to -0.4; P=0.01]. The overall combined MDs of RNFL thickness in relation to moderate OSAS and severe OSAS were -2.49 µm (95% CI: -4.54 to -0.44; P=0.02) and -6.36 µm (95% CI: -8.4 to -4.32; P<0.001). But no significant difference was observed in mild OSAS; the combined MD was -2.05 µm (95% CI: -4.23 to 0.13; P=0.07). Association was also observed in OSAS and RNFL thickness of the inferior quadrant, with a combined MD of -3.31 µm (95% CI: -6.19 to -0.42; P=0.02).
  
  
  CONCLUSIONS
  This meta-analysis provides evidence that OSAS is associated with RNFL thickness. Furthermore, it was observed that the greater the severity of OSAS, the greater the loss of RNFL. Among the 4 quadrants observed, the most affected quadrant was the inferior quadrant, and the least affected was the temporal quadrant. OSAS may have an impact on changes in RNFL and therefore more attention should be paid to patients with this condition.
authors.affiliation: *Department of Ophthalmology, The Fifth Affiliated Hospital, Sun Yat-sen University †Department of Cardiology, Zhuhai People's Hospital, Zhuhai, China.
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Zhao
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Yang
authors.forename: Jie-Chang
authors.initials: JC
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Zheng
authors.forename: Ping-Ping
authors.initials: PP
authors.lastname: Liu
authors.forename: Qin
authors.initials: Q
authors.lastname: Li
mesh_terms: D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D012160:Retina / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D041623:Tomography, Optical Coherence