The Role of Retrobulbar and Retinal Circulation on Optic Nerve Head and Retinal Nerve Fibre Layer Structure in Patients with Open-Angle Glaucoma over an 18-Month Period

Background/aims Evidence suggests that vascular abnormalities play a role in the pathogenesis of open-angle glaucoma (OAG) in some patients. This study aims to assess changes in retrobulbar and retinal blood flow over time in patients with glaucoma and examine their relationship to glaucomatous progression, as determined by retinal and optic nerve structure.Methods In this observational study, 103 patients with OAG were examined at baseline and 18 months follow-up. Retrobulbar blood flow was measured by colour Doppler imaging in the ophthalmic, central retinal and temporal posterior ciliary artery (TPCA) and nasal short posterior ciliary artery. Retinal capillary blood flow was measured by confocal scanning laser Doppler. Peripapillary retinal nerve fibre layer thickness was assessed by optical coherence tomography. Nonparametric Wilcoxon signed ranks tests were used to assess for any statistically significant changes between the baseline and 18-month visits for the retrobulbar and retinal flow, as well as the structural parameters.Results In general, retinal and retrobulbar blood flow parameters decreased over 18 months. Thinning of the optic disc rim and increase in cup area were associated with a higher resistance index (p=0.0334) and lower peak systolic velocity of TPCA (p=0.0282), respectively. A higher amount of retinal zero pixel blood flow correlated with a greater increase in cup/disc ratio (p=0.0170).Conclusions Reductions in retrobulbar and retinal blood flow over time were associated with structural glaucomatous progression, as indicated by retinal and optic nerve changes.