Color Doppler imaging analysis of ocular vessel flow velocity in glaucomatous and normal subjects

Background: The mechanisms of glaucomatous damage are still unclear. Damage to the optic nerve head can be caused by increased intraocular pressure (IOP) alone; vascular factors, with or without elevated IOP, have been implicated in the development of glaucoma. Color Doppler imaging is a recent advance in the diagnosis of blood flow at specific locations by simultaneous B-mode imaging. This technique was used to measure and compare the velocities of blood flow and vascular resistance of glaucomatous patients and normal controls. Materials and methods: Using color Doppler imaging, blood flow velocities in the central retinal artery (CRA), lateral posterior ciliary artery (LPCA) and medical posterior ciliary artery were studied. Fifteen patients with primary open-angle glaucoma (POAG), 14 patients with normal-tension glaucoma (NTG) and 20 normal subjects participated in this program. The mean values of the peak systolic velocity, end diastolic velocity (EDV) and resistivity index (RI) of the three groups were compared. Results: Compared with normal subjects, the POAG patients showed a statistically significant (p < 0.05) decrease in mean EDV and an increase in mean RI in the CRA. The NTG patients showed similar changes; however, the results appear to be even more significant compared with normal subjects (p < 0.01). In addition, the NTG patients showed a statistically significant lower mean EDV and higher mean RI in the LPCA (p < 0.05). There was no statistically significant difference between the POAG and NTG groups in all three of the indexes. Conclusion: Glaucoma patients, especially those with NTG, have lower blood flow velocity and higher vascular resistance in their retrobulbar vessels compared with normal controls.