Optic Nerve Blood Flow in Glaucoma: Effect of Systemic Hypertension

Purpose: To investigate optic nerve head blood flow in patients with glaucoma and to assess the effect of systemic hypertension.

Methods: This study included 24 eyes of 24 patients with primary open-angle glaucoma. Eleven of these patients had a history of systemic hypertension. Results in patients with glaucoma were compared with those of 13 eyes of 13 age-matched normal controls. Determinations of relative optic nerve head blood velocity, volume, and flow were obtained with laser Doppler flowmetry in the superotemporal and inferotemporal neuroretinal rim and also in the cup. Means of the velocity, volume, and flow of these three measurement sites were calculated for each subject.

Results: Mean overall optic nerve head blood flow was 29% lower in glaucoma patients than in normal controls (t test, P < .001). This decrease in flow was mainly caused by a decrease of 23% in mean blood velocity (P < .001). Mean flow in glaucoma patients without systemic hypertension was 26% lower than that of glaucoma patients with hypertension (Tukey honest significant difference test, P = .05). A significant direct correlation was observed between mean flow and mean blood pressure (R = 0.51, P < .02).

Conclusions: Optic nerve blood flow is reduced in glaucoma patients. Glaucoma patients without systemic hypertension have lower optic nerve blood flow than those with hypertension. Our results raise concerns that treatment of systemic hypertension may further decrease optic nerve blood flow in glaucoma patients.