['To evaluate newly diagnosed non-arteritic anterior ischaemic optic neuropathy (NAION) patients for the existence of an associated sleep apnoea syndrome.', 'Newly identified NAION patient underwent polysomnography. The prevalence of sleep apnoea in NAION patients was compared to the prevalence previously found in the general population. Hypertension, diabetes, hyperlipidaemia, and atheromatous lesions of carotid vessels as classic risk factors associated with NAION were also identified.', '27 consecutive newly diagnosed NAION patients (18 men and nine women, mean age 65 (SD 8) years, body mass index 27.2 (3.8) kg/m2) were included in the study. 24 of these 27 NAION patients (89%) exhibited a sleep apnoea syndrome (respiratory disturbance index: 37.2/h (SD 18.3/h). Risk ratio for a NAION patient to have sleep apnoea was 4.9 compared to the general population (p < 0.001). Sleep apnoea was 1.5-2-fold more frequent than the rate of the other identified risk factors typically associated with NAION (hypertension, diabetes).'] Is non-arteritic anterior ischaemic optic neuropathy nearly systematically associated with obstructive sleep apnoea?