Retrobulbar blood flow velocities in open angle glaucoma and their association with mean arterial blood pressure

PURPOSE. A number of previous studies have shown that blood velocities in retrobulbar arteries, as assessed with color Doppler imaging (CDI), are reduced in primary open angle glaucoma (POAG) patients, indicative of reduced blood flow to the eye. In the present study, the authors hypothesized that patients with POAG show an abnormal association between retrobulbar blood flow velocities as assessed with CDI and blood pressure, indicative of vascular dysregulation. METHODS. A total of 252 POAG patients and 198 healthy age-matched control subjects were included. Mean flow velocity (MFV) in the ophthalmic artery (OA), posterior ciliary artery (PCA), and central retinal artery (CRA) were measured with CDI. Mean arterial blood pressure was measured noninvasively using automated oscillometry, and intraocular pressure was measured using Goldmann applanation tonometry. RESULTS. Intraocular pressure was increased in POAG patients compared with healthy controls (P< 0.01). Mean arterial blood pressure was not different between groups. All blood flow velocities were significantly reduced in POAG patients compared with healthy control subjects (P< 0.01 each). The correlation between MFV and mean arterial blood pressure in the CRA was stronger in POAG subjects than in healthy control subjects. CONCLUSIONS. These data indicate that blood flow velocities in retrobulbar vessels are reduced in POAG patients compared with healthy control subjects. In addition, an abnormal correlation between blood velocities and mean arterial blood pressure was found in POAG. This suggests vascular dysregulation and supports the concept that reduced ocular blood flow in glaucoma is not solely a consequence of the disease.