Color Doppler imaging of the retrobulbar circulation in glaucoma.

Color Doppler imaging is a noninvasive technique for investigating the retrobulbar circulation, showing specific retrobulbar vessels Ophthalmology Department, The Royal Victoria Hospital, Belfast, Northern Ireland and measuring blood velocity characteristics within these vessels. Color Doppler imaging is reproducible and has been used by many investigators to study blood velocity in the ophthalmic artery, the central retinal artery, and the short posterior ciliary arteries. The technique has shown statistically significant reductions in the flow velocities and increases in the resistance indices of these vessels in both primary open-angle glaucoma and normal tension glaucoma in comparison with normal control subjects. These changes correlate with disease severity and asymmetry and illustrate a compromised circulation in this region. Intraocular pressure and vasospasm have been shown to affect blood flow velocities in the same circulation. This article discusses studies that have elucidated these changes in various subpopulations of glaucoma subjects in an attempt to determine hemodynamic alterations between these disease types.