Abstract
Abstract: :
Purpose: To investigate the relation between blood flow parameters of the retrobulbar vessels measured by means of color doppler imaging (CDI) and fluorescein filling defects of the optic nerve head in patients with normal tension glaucoma (NTG) and control subjects. Methods: Twenty-nine patients with NTG and twenty-nine healthy subjects were included in this study (match criteria: age and sex). Blood flow velocities (peak systolic velocity PSV, end diastolic velocity EDV) and resistive indices (RI) of the ophthalmic artery (OA), the central retinal artery (CRA) and of the temporal and nasal short posterior ciliary arteries (TPCA, NPCA) were measured with CDI. Fluorescein angiograms were performed with a Scanning Laser Ophthalmoscope. The extent of absolute fluorescein filling defects of the optic nerve head in relation to the optic nerve head was assessed. Results: The peak systolic velocity of the OA, the peak systolic velocity and end-diastolic velocity of the CRA and of the TPCA and NPCA were statistically significantly reduced in NTG (p<0.05). The resistive indices of the CRA, the TPCA and NPCA were significantly increased in NTG (p<0.01). The fluorescein filling defects were significantly larger in NTG (p<0.01) than in healthy controls and significantly negatively correlated to the peak systolic velocity and end-diastolic velocity of the CRA (PSV CRA: p<0.01, r=-0.41; EDV CRA: p<0.01, r=-0.34), to the peak systolic velocity and end-diastolic velocity of the NPCA (PSV NPCA: p<0.05, r=-0.34; EDV NPCA: p<0.01, r=-0.38), and to the end-diastolic velocity of the TPCA (p<0.05, r=-0.29). Furthermore, a significant correlation was found with the resistive index of both PCAs (RI NPCA: p<0.05, r=0.28; RI TPCA: p<0.05; r=0.29. Conclusion: Patients with NTG had reduced blood flow velocities and higher resistive indices in most retrobulbar vessels and fluorescein filling defects were larger compared to controls. The filling defects were correlated to end-diastolic velocities and resistive indices of the PCAs and to blood flow velocities of the CRA. Capillary loss of the optic nerve head may be related to higher peripheral downstream resistance and reduced blood flow velocities of the retrobulbar vessels as a sign a of impaired perfusion to the optic nerve head in glaucoma.
Keywords: 498 optic disc • 331 blood supply