To evaluate the effect of hemodialysis on choroidal thickness and the choroidal vascularity index (CVI) in patients with end-stage renal disease (ESRD) by using swept-source optical coherence tomography.Thirty-two eyes of 32 patients with ESRD undergoing hemodialysis were recruited prospectively. Detailed ophthalmologic examinations and swept-source optical coherence tomography were performed immediately before and after hemodialysis. Choroidal thickness maps were generated automatically by using built-in software. The CVI was calculated using binarized choroidal optical coherence tomography images. Systemic parameters such as body weight and blood pressure were also measured. The changes in systemic and ocular parameters during hemodialysis were evaluated. Subjects were divided into 2 groups (diabetes mellitus [DM] vs non-diabetes mellitus) for subgroup analysis.Total choroidal thickness showed a significant overall decrease after hemodialysis (-10.9 ± 14.0, P <.001). In the subgroup analysis, total choroidal thickness significantly decreased in both patients with DM (-11.3 ± 13.6, P = .004) and those without (-10.6 ± 14.9, P = .020), but the reduction of choroidal thickness was observed in more subfields in patients with DM than in those without. The CVI did not significantly change after hemodialysis (P = .717). No significant systemic and ocular factors affected the changes in total choroidal thicknesses.Choroidal thickness significantly decreased after hemodialysis in most subfields regardless of the presence of DM. Peri-hemodialysis choroidal changes could be considered in the management of patients with ESRD. Swept-source optical coherence tomography can provide ample and reliable quantitative data for monitoring ocular hemodynamic changes.