Abstract
Purpose: :
systemic and ocular vascular abnormalities have demonstrated to be risk factors for the onset and the progression of normal-tension glaucoma (NTG). The present study was conducted to evaluate the prevalence of these factors and to investigate the correlations among them in NTG patients.
Methods: :
cold-induced capillaroscopy features, diastolic ocular perfusion pressure (dOPP), endothelin-1 (ET-1) and nitrates (NO2) plasma values, and retrobulbar haemodynamics by Color Doppler Imaging were determined in forty-four patients with NTG and forty healthy controls.
Results: :
in NTGs than in controls cold-induced altered capillaroscopy was more frequent (72.7% vs 5.0%, p<0.001), dOPP was lower (57.89 ±4.30 mmHg vs 67.07 ±6.44 mmHg, p<0.001), ET-1 and NO2 values were respectively higher and lower (1.62 ±0.22 pg/ml vs 1.12 ±0.20 pg/ml, p<0.001, and 142.17 ±14.34 µmol/mg prot vs 231.30 ±6.16 µmol/mg prot, p<0.001), resistivity index in ophthalmic artery (OA-RI) was higher (0.76 ±0.03 vs 0.64 ±0.03, p<0.001). In NTGs an altered capillaroscopy was associated with higher ET-1 and higher OA-RI (p=0.015 and p=0.011). OA-RI was negatively related to dOPP and NO markers (r=-0.291, p=0.022, and r=-0.323, p<0.001) and positively related to ET-1 (r=0.395, p=0.007).
Conclusions: :
the present study confirmed that many vascular risk factors are involved and interrelated in the pathogenesis of normal-tension glaucoma. The imbalance of the endothelin-1/nitric oxide system resulted to be the likely common substrate for both systemic and ocular vascular dysregulation. An inappropriate retrobulbar vasoconstriction in response to low diastolic ocular perfusion pressure seemed to be a main determinant of optic nerve damage in vasospastic subjects with normal-tension glaucoma.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • nitric oxide • blood supply