Abstract: Objective To evaluate blood flow velocities, resistance indices (RI) and pulsatile indices (PI) of ophthalmic artery (OA) in both orbits of patients in the acute and chronic phases of unilateral optic neuritis (ON) and compare these with equivalent findings in healthy control subjects. Methods Forty consecutive patients with acute unilateral optic neuritis who had undergone color Doppler ultrasound examination instead of hormone therapy in Chinese PLA General Hospital from October 2009 to June 2013 were selected. Diagnosis of optic neuritis was based on clinical presentation and visual evoked potentials. The peak systolic velocity (PSV), end-diastolic velocity (EDV), RI and PI of both eyes in all patients were measured. The paired t test was applied for affected side and intact side for statistical comparison. Another 40 optic neuritis patients in chronic phase were selected (Some patients enrolled in our study had a history of acute unilateral optic neuritis for more than one year). Results Compared with the affected side, the value of PSV, RI and PI in the intact side in patients with acute unilateral optic neuritis was significantly higher (42.60±10.79) cm/s vs (30.33±10.07) cm/s; (0.75±0.035) cm/s vs (0.67±0.059) cm/s; (1.59±0.21) cm/s vs (1.32±0.27) cm/s, P＜ 0.05, while the ophthalmic artery EDV was of no significant difference. In addition, in optic neuritis of chronic phase, no significant differences were observed in blood flow rate, RI or PI. Conclusion The value of PSV, RI and PI increases in patients with acute unilateral optic neuritis, and the hemodynamic changes of ophthalmic artery in both acute and chronic unilateral ON have a certain rule. The ultrasound examination of ophthalmic artery is of significance in diagnosis of acute and chronic unilateral ON.