Ophthalmic Artery and Superior Ophthalmic Vein Blood Flow Dynamics in Glaucoma Investigated by Phase Contrast Magnetic Resonance Imaging.

PRECIS Ophthalmic artery and superior ophthalmic vein blood flow were quantified by Phase contrast MRI and seemed lower in glaucoma. Venous flow dynamics was different in glaucoma patients with a significantly decreased pulsatility. INTRODUCTION Studies using color Doppler imaging and OCT flowmetry strongly suggested that vascular changes are involved in the pathophysiology of glaucoma, but the venous outflow has been little studied beyond the episcleral veins. This study measured the ophthalmic artery (OA) and the superior ophthalmic vein (SOV) flow by phase contrast magnetic resonance imaging (PC MRI) in glaucoma patients compared to controls. METHODS 11 primary open angle glaucoma patients, with a mean±SD visual field deficit of -2.3±2.7▒dB and RNFL thickness of 92±13▒µ, and 10 controls of similar age, were examined by PC MRI. The mean, maximal and minimal flow over cardiac cycle were measured. The variation of flow (ΔQ) was calculated. RESULTS The OA mean±SD mean flow was 13.21±6.79 in patients and 15.09±7.62▒mL/min in controls (P=0.35) and the OA maximal flow was 25.70±12.08▒mL/min in patients, and 28.45±10.64▒mL/min in controls (P=0.22). In the SOV the mean±SD mean flow was 6.46±5.50▒mL/min in patients and 7.21±6.04▒mL/min in controls (P=0.81) and the maximal flow was 9.06±6.67 in patients versus 11.96±9.29▒mL/min in controls (P=0.47). The ΔQ in the SOV was significantly lower in patients (5.45±2.54▒mL/min) than in controls (9.09±5.74▒mL/min), P=0.04. DISCUSSION Although no significant difference was found, the mean and maximal flow in the OA and SOV seemed lower in glaucoma patients than in controls. The SOV flow waveform might be affected in glaucoma, corroborating the hypothesis of an impairment of venous outflow in those patients.