Association between sleep apnea syndrome and nonarteritic anterior ischemic optic neuropathy

Objective: To determine if patients with nonarteritic ischemic optic neuropathy (NAION) have sleep apnea syndrome (SAS), an entity characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption. Methods: We recruited 17 patients with NAION and 17 age- and sex-matched controls from patients referred for treatment because of suspected restless legs syndrome. We performed overnight polysomnography and determined the respiratory disturbance index during night sleep, a value used to diagnose and grade SAS. We compared the proportions of patients with SAS among patients with NAION and matched controls using the X² test. Additionally, we compared the proportions of patients with SAS among patients with NAION and a large SAS prevalence study using the binomial test. Results: Twelve (71%) of 17 patients with NAION had SAS. According to the respiratory disturbance index, 4 patients (24%) had mild, 4 patients (24%) had moderate, and 4 patients (24%) had severe SAS. Only 3 (18%) of 17 controls had SAS (P=.005). In the 45- to 64-year age group, 4 (50%) of 8 patients with NAION had SAS; 51 (11.9%) of 430 of the random sample in the prevalence study had SAS (P=.005). In the group older than 64 years, 8 (89%) of 9 patients with NAION had SAS; 18 (24%) of 75 of the random sample in the prevalence study had SAS (P<.001). Conclusions: We found a high prevalence of SAS in patients with NAION, which supports previous case reports suggesting that such an association exists. This association may explain why approximately 75% of all patients with NAION discover visual loss on first awakening or when they first use vision critically after sleeping. Our findings indicate that SAS may play an important role in the pathogenesis of NAION.