Purpose: To evaluate the optical coherence tomography-angiography (OCT-A) findings and choroidal vascularity index (CVI) of patients followed with a diagnosis of obsessive-compulsive disorder (OCD) by comparing them with the healthy control group (HCG). Methods: This prospective study included 33 patients diagnosed with OCD and 32 HCG patients who followed up for at least 3 months. OCT-A images were obtained to evaluate the microvascular circulation, and enhanced HD line images were obtained for the CVI calculation of all patients. Results: Statistical analysis results revealed that the rates of superficial vascular density in the fovea region and deep vascular density in the parafovea region decreased in the OCD group compared to the HCG group (P = 0.003 and P = 0.010, respectively). Subfoveal choroidal thickness values of the OCD group were lower than those of the HCG group (P = 0.008). While total choroidal area and lumen area values were lower in the OCD group than in the HCG group (P < 0.001 and P < 0.001, respectively); CVI values were similar in both groups (P = 0.436). Conclusion: The use of the OCT-A device, which is a non-invasive method for detecting retinal and choroidal changes in OCD cases, may provide insight into the pathogenesis of the disease.