Abstract: Objective To investigate the short-term effect of single intravitreal ranibizumab injection on retrobulbar blood flow in patients with retinal vein occlusion. Methods In this prospective interventional study, patients with macular edema secondary to retinal vein occlusion were included. The hemodynamic parameters of the ophthalmic artery, central retinal artery and posteriorciliary artery comprising peak systolicvelocity, end-diastolic velocity, and resistive index were measured by using color doppler imaging in both injected and uninjected fellow eyes at baseline and one week after the injection. Results Intravitreal ranibizumab induced a significant reduction in the peak systolic velocity and end-diastolic velocity and a significant rise in the resistive index of the central retinal artery and short posterior ciliary artery of the injected eye. After injection, there was any significant difference between injected and uninjected eyes in the peak systolic velocity, end-diastolic velocity, and resistive index values of central retinal artery and short posterior ciliary artery. Conclusion In patients with macular edema secondary to retinal vein occlusion, intravitreal injection of ranibizumab alters retrobulbar blood flow velocities in injected eyes in the short-term period

Key words: ranibizumab, intravitreal injection, retinal vein occlusion, retrobulbar hemodynamics