To determine whether lower blood velocities and high resistive index in the retrobulbar arteries are primary or secondary to glaucomatous damage in patients with open-angle glaucoma.

Color Doppler imaging was performed in 32 glaucomatous patients with unilateral visual field loss and in 31 control subjects. Peak systolic velocity and end diastolic velocity were measured, and resistive index was calculated in the central retinal artery and short posterior ciliary arteries.

In patients with glaucoma, both the more affected and the contralateral eyes with normal visual fields had significantly lower peak systolic velocity and end diastolic velocity in their central retinal artery and short posterior ciliary arteries than did the control subjects of similar age (P ≤ .03). The resistive index of the central retinal artery of both eyes of patients with glaucoma was also significantly higher than in the control subjects (P = .001). When considering the 16 patients who had the greatest visual field asymmetry, the more affected eyes had lower peak systolic velocity and end diastolic velocity in the central retinal artery than the contralateral eyes did (P = .02).

Even eyes with normal visual fields in patients with asymmetric disease had decreased blood velocities in their retrobulbar vessels, suggesting that these circulatory changes probably precede detectable damage. Furthermore, the finding of lower central retinal artery blood velocities in the more affected eye of asymmetric patients suggests that low blood velocities may be one of the lateralizing factors in those patients and that they have a possible role in the pathogenesis of the disease.