ObjectiveTo analyze retrospectively the risk factors of nonarteritic anterior ischemic optic neuropathy (NAION). MethodsThe complete clinical data of 116 patients (134 eyes) were collected. All patients were asked in detail about the disease history and symptoms and were examined for the visual acuity, intraocular pressure, fundus, visual field and fundus fluorescein angiography (FFA), blood pressure, blood glucose, blood fat and head MRI or CT. Suspicious cases and patients with incomplete clinical data were excluded. The relationship between NAION and age, visual field, FFA, systemic and ocular factors, onset seasons were retrospectively analyzed. Results80 patients (68.97%) were 55 to 70 years old. 97 patients (83.7%) had systemic diseases, including 38 patients (39.2) with diabetes mellitus, 32 patients (32.9%) with hypertension (8 patients had low blood pressure at night), 28 patients (28.9%) with hyperlipidemia, 16 patients (16.5%) with cerebrovascular diseases (mainly lacunar cerebral infarction), 6 patients (6.2%) with coronary heart disease. There were 8 patients with ocular factors, including 3 patients (2.6%) with cataract surgery history, 5 patients (4.2%) with small optic discs. The difference of percentage of with or without diabetes mellitus and hypertension was significant (χ2=362, 259; P < 0.05). There were 27.6% patients with disease onset at March to April, 24.1% patients with disease onset at September to October, much higher than other months (χ2=580, P < 0.05). Visual field test results showed that 49 eyes (36.5%) had inferior visual field defect, 12 eyes (9.0%) had superior visual field defect. FFA showed that in the early stage 103 eyes (76.9%) had optic weak fluorescence, 13 eyes (9.7%) had strong fluorescence; in the late stage, 110 eyes (82.1%) had strong fluorescence, 8 eyes (6.0%) had weak fluorescence. ConclusionsDiabetes mellitus, hypertension may be the system risk factors of NAION. The seasonal variation from spring to summer and from autumn to winter may also be another risk factor for the onset of NAION.