Background: In the pathophysiology of open-angle glaucoma altered perfusion of the optic nerve head is of importance. Up to now these disturbances were presumed to be the chief cause of glaucomatous damage in patients with normal tension glaucoma showing other vascular disturbances like migraine or tinnitus.
Patients and methods: Peak systolic velocity (PSV) and end-diastolic velocity (EDV) were measured and the resistive index (RI) was calculated by colour Doppler imaging (CDI) in the ophthalmic artery (OA), central retinal artery (CRA) and in the short and long posterior ciliary arteries (SPCA, LPCA) in 18 patients with normal tension glaucoma (NTG), in 18 patients with high tension glaucoma (HTG) and in 18 normal control subjects.
Results: In an upright sitting position both glaucoma groups showed statistically significant decreases in PSV and EDV in CRA and SPCA compared to the control subjects. HTG when compared to NTG and normal subjects showed statistically significant decreases of EDV and statistically significant increases of RI in LPCA. In addition, compared to normal subjects, HTG patients showed statistically significant increases of RI in both OA and SPCA.
Discussion: Both glaucoma groups showed decreased blood flow velocities in the small retrobulbar vessels in an upright sitting position. Normal tension glaucoma patients with symptoms of vasospasms compared to patients with high tension glaucoma showed only small differences in ocular haemodynamics.