A new characterization for nonarteritic anterior ischemic optic neuropathy.

This study is to investigate the clinical characteristics of patients with nonarteritic anterior ischemic optic neuropathy (NAION). Totally 133 patients (156 eyes) were included in this study. At the first visit and follow-up visits, the patients were subjected to the ophthalmic evaluations, including the fundus photography, visual field (VF) test, fluorescein fundus angiography, and optical coherence tomography (OCT). The visual acuity (VA) of 156 eyes and the VF of 148 eyes were evaluated. For the VA assessment, 59 (38%), 67 (43%), and 30 (19%) cases presented with an initial VA ≥ 20/40, between 20/40 and 20/400, and ≤ 20/400, respectively. VA was improved in 44% and deteriorated in 8% of the patients with VA < 20/20 after NAION onset. Inferior or superior altitudinal defects, constricted fields, and nasal steps were the most common VF defects. In the eyes with VF defects, 32 cases (22%) were improved, and 25 cases (17%) were worsened. In the 61 cases (39%) with VA ≤ 20/200 at NAION onset, neuroepithelial detachment in the fovea was found in 37 eyes (61%). For the optic disc assessment, retinal nerve fiber layer (RNFL) thickening was the most common symptom of NAION. Out of the 36 eyes with ONA or DR, 72% showed VA improvement after the NAION occurrence in the contralateral eye. Poor microcirculation perfusion in the bilateral optic nerve hypoplasia (ONH) might be the underlying mechanism for NAION, which could be relieved by compromising the blood supply to the one side.