ObjectiveTo determine the correlation between obstructive sleep apnea syndrome (OSAS) and nonarteritic ischemic optic neuropathy (NAION).MethodsIt was a perspective study. A total of 41 consecutive patients with NAION (NAION group) and 41 age- and sex-matched physical examination subjects (control group) in Xi’an No.3 Hospital from December 2016 to December 2018 were enrolled in this study. The apnea hypopnea index (AHI, the number of sleep apneas per hour) was monitored using a polysomnography for patients in NAION group and control group. At the same time, the blood oxygen saturation was continuously recorded. The OSAS can be diagnosed if the AHI value was ≥5. OSAS severity was graded as mild: 5≤AHI＜15; moderate: 15≤AHI＜30; severe: AHI ≥30. The grading of OSAS severity between two groups was compared by Fisher's exact test. The AHI and minimum blood oxygen saturation were compared between NAION group and control group using the Mann-Whitney U test. Spearman correlation analysis was performed on the correlation between OSAS and NAION.ResultsAmong the patients in the NAION group, 31 patients (75.61%) were diagnosed with OSAS. Among them, 6 patients (14.63%) were mild, 9 patients (21.95%) were moderate, and 16 patients (39.03%) were severe. In the control group, 19 patients (46.34%) were diagnosed with OSAS. Among them, 10 patients (24.39%) were mild, 5 patients (12.20%) were moderate, and 4 patients (9.75%) were severe. The difference of OSAS patients of mild, moderate and severe between two groups were statistically significant (Z=0.235, 0.245, 0.312; P=0.012, 0.014, 0.032). The average AHI of patients in the NAION group was 20.25±7.74, and the mean minimum oxygen saturation at night was (87.38±5.53)%. The average AHI of the control group was 18.67±11.67, and the mean minimum oxygen saturation at night was (85.06+4.25)%. The differences of the mean AHI and mean minimum oxygen saturation between two groups were statistically significant (Z=1.124, 2.317, P=0.003, 0.020). There was a positive correlation between OSAS and NAION (Spearman correlation coefficient=0.229, P=0.030).ConclusionThere is a positive correlation between OSAS and NAION.