To evaluate the impact of retinal blood flow on optic nerve head (ONH) morphology in patients with open-angle glaucoma (OAG) with and without diabetes mellitus (DM).

A total of 66 patients with OAG (14 with DM, 52 without DM) were assessed at baseline and 3-year follow-up for retinal capillary blood flow using confocal scanning laser Doppler and ocular structure using Heidelberg retinal tomography and optical coherence tomography.

Change in retinal tissue with zero blood flow in the superior and inferior retina was found to have a strong correlation with ONH changes in diabetic patients (r≥0.90, p≤0.03); however, no relation was found in the nondiabetic cohort. There were also significant changes in inferior mean flow that strongly correlated with changes in cup area (r = 0.97, p = 0.0029), cup/disc area ratio (r = 0.96, p = 0.0070), linear cup/disc ratio (r = 0.93, p = 0.0172), rim area (r = −0.97, p = 0.0036), and rim volume (r = −0.95, p = 0.0084) in diabetic patients only, while changes in the superior mean flow were only significantly associated with cup area (r = −0.30, p = 0.0498), cup volume (r = −0.36, p = 0.0178), and rim volume (r = 0.35, p = 0.0193) in nondiabetic patients.

In this cohort of patients with OAG, changes in retinal capillary blood flow correlated more strongly with changes in ONH morphology in patients with DM than in those without DM. These data suggest that changes in retinal blood flow may play a larger role in glaucomatous ONH progression in patients with OAG with DM.