Systemic vascular dysregulation and retrobulbar hemodynamics in normal-tension glaucoma.

PURPOSE To investigate the influence of systemic vascular dysregulation on retrobulbar hemodynamics in normal-tension glaucoma (NTG). METHODS Forty-four untreated patients with NTG and 40 healthy controls matched for age, sex, and intraocular pressure were included. Cold-induced nailfold capillaroscopic features, mean and diastolic ocular perfusion pressures (mOPP, dOPP), endothelin-1 (ET-1) and nitric oxide markers, as nitrates (NO(2)), plasma values were recorded. Peak-systolic velocity, end-diastolic velocity (EDV), and resistivity index (RI) were measured in the ophthalmic artery (OA), short posterior ciliary arteries, and the central retinal artery by color Doppler imaging. Differences between groups were determined by Student's t-test. Relationships among ET-1, NO(2), OPPs, and retrobulbar hemodynamics were assessed using correlation and multiple linear regression analyses. RESULTS Altered capillaroscopy was more frequent (72.7% vs. 5.0%, P < 0.001), mOPP and dOPP values were lower (44.54 ± 2.81 vs. 52.18 ± 4.47 mm Hg; 57.89 ± 4.30 vs. 68.28 ± 6.91 mm Hg; P < 0.001), and ET-1 and NO(2) values were respectively higher and lower (1.62 ± 0.22 vs. 1.12 ± 0.20 pg/mL and 142.17 ± 14.34 vs. 231.30 ± 6.16 μmol/mg prot; P < 0.001) in patients than the same values in controls. EDV was lower and RI higher in OA (5.87 ± 1.17 vs. 11.41 ± 2.30 cm/s; 0.76 ± 0.03 vs. 0.64 ± 0.03; P < 0.001) in subjects with NTG than in controls. In patients RI-OA was positively related to ET-1 (t = 2.704, P = 0.010) and negatively related to NO(2) (t = -4.477, P < 0.001). CONCLUSIONS Impaired retrobulbar hemodynamics may proceed from a vascular endotheliopathy in patients with NTG.