Optic disc evaluation by optical coherence tomography in nonarteritic anterior ischemic optic neuropathy

PURPOSE. To describe the characteristics of the optic nerve head (ONH) in patients with nonarteritic anterior ischemic optic neuropathy (NAION) and compare them with control subjects by using optical coherence tomography (OCT). METHODS. Patients with NAION underwent a complete ophthalmic examination, including OCT scanning of the ONH at diagnosis. The examination was repeated 1.5, 3, and 6 months later. Age- and sex-matched control subjects with no ocular disease underwent a similar evaluation. Data were obtained by using the ONH analysis protocol of the StratusOCT (Carl Zeiss Meditec, Dublin, CA). RESULTS. Twenty-three patients and 23 control subjects were included. In eyes with NAION, the vertical integrated rim area decreased significantly ( P < 0.01) from the acute phase to the 6-month visit. The cup-to-disc (C/D) area ratio increased significantly ( P = 0.002) from the acute examination to the 3-month visit. There was a significant difference between the NAION fellow eyes and the control eyes in C/D ratio, evaluated by slit lamp funduscopy ( P < 0.001), and in the C/D area ratio ( P = 0.001). The vertical integrated rim area was significantly ( P = 0.001) greater in NAION fellow eyes than in control eyes. There was no significant difference in optic disc area or vertical disc diameter among the control eyes, NAION-affected eyes, and NAION fellow eyes. CONCLUSIONS. Although patients with NAION have lower C/ D ratios than does the normal population, with a higher level of nerve fiber crowding, there was no difference in optic disc size between patients with NAION and control subjects. After the development of NAION, 47.8% of eyes had a C/ D ratio that differed from that in the fellow eye by more than 0.1.