Twelve hour variability of ocular blood flow parameters in healthy subjects and patients with primary open angle glaucoma

Abstract

Abstract Purpose: Ocular perfusion abnormalities have been implicated in the pathogenesis of primary open angle glaucoma (POAG). More specifically it has been reported that POAG is associated with vascular dysregulation and ischemia/reperfusion phenomena. In the present study we compared the twelve hour variability of ocular blood flow parameters in healthy subjects and patients with POAG. Methods: In 16 patients with POAG and 16 healthy age‐matched controls ocular and systemic blood flow parameters and intraocular pressure was measured every 2 hours over 12 hours. Ocular hemodynamic measurements included optic nerve head blood flow and choroidal blood flow assessed with laser Doppler flowmetry, fundus pulsation amplitude assessed with laser interferometry and retrobulbar blood velocities with color Doppler imaging. A repeated measures ANOVA model was used to compare variability among these measurements between the two groups of patients. Results: Most of the outcome variables showed higher fluctuations in patients with PAOG than in healthy controls. These changes were not associated with ocular perfusion pressure or intraocular pressure. Changes over time were, however, correlated among the different ocular hemodynamic outcome measures in patients with POAG, but not in healthy controls. Conclusions: Patients with POAG show an abnormal diurnial fluctuation of ocular blood flow parameters. Since we observed correlations between these fluctuations as assessed with different methods this does not appear to be related to statistical errors associated with the measurement techniques. These data support the hypothesis of vascular dysregulation in POAG.