Background/aim: To investigate the effect of deep sclerectomy on retrobulbar blood flow. Materials and methods: This prospective study included 20 eyes of 20 patients with open angle glaucoma. Color Doppler imaging (CDI) examinations were performed before and 2, 12, and 24 weeks after deep sclerectomy. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were measured for the ophthalmic artery (OA), central retinal artery (CRA), and temporal and nasal short posterior ciliary arteries (SPCAs) at each examination and the results were compared. Results: A significant decrease was determined in intraocular pressure (IOP) (P < 0.001) and a significant increase in ocular perfusion pressure (OPP) (P < 0.001) at all postoperative examinations. The EDV in OA increased significantly (P < 0.001), but the change in RI was not statistically significant (P = 0.67). EDV increased and RI decreased significantly in CRA and SPCA (P < 0.001). Conclusion: Deep sclerectomy decreases IOP and increases OPP significantly. Retrobulbar blood flow was seen to improve after deep sclerectomy.