Abstract
Purpose: :
Laser Speckle Flowgraphy (LSFG-NAVI, Softcare Ltd, Fukuoka, Japan) is a non-invasive technique which uses the laser speckle phenomenon to assess the ocular circulation. The aim of this study was to investigate the difference in optic nerve circulation between normal subjects and the patients with normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG).
Methods: :
Age-matched 41 NTG patients, 15 POAG patients, and 38 normal subjects (56.5± 5.6, 58.2 ± 4.2, and 58.5 ± 6.0 respectively) were included in this study. The patients with NTG and POAG had glaucomatous visual field loss, according to the Anderson-Pattela classification. Intraocular pressure (IOP) and systemic blood pressure were recorded and then optic nerve circulation was measured with LSFG-NAVI. The microcirculation of the optic nerve head (ONH) was evaluated with LSFG-NAVI parameters calculated with the equipped software (LSFG Analyzer, ver. 3.0.43.0, Softcare Ltd), including mean blur rate (MBR) in the vessel area (MV), tissue area (MT) and all areas (MA), and with time analysis parameters, including skew, blowout score (BOS), blowout time (BOT), rising rate, and falling rate. The optic disc structure measured with HRT-II, the average thickness of the retinal nerve fiber layer (avg. RNFLT) with Stratus-OCT, and the visual field with a Humphrey Field Analyzer (HFA, 30-2 SITA standard) were compared with Mann-Whitney’s U test and the statistical significance was set at p<0.05. The correlation was evaluated with a Spearman rank correlation coefficient.
Results: :
There were no significant differences in IOP, systemic blood pressure, or mean deviation of HFA between NTG and POAG patients. MV in ONH was significantly decreased in the patients with NTG (43.3 ± 9.0 AU, p<0.001) and POAG (39.3 ± 8.5 AU, p<0.001), compared to normal subjects (51.5 ± 5.2 AU). MT was significantly decreased in the patients with NTG (12.0 ± 3.4 AU, p<0.001) and POAG (10.1 ± 2.0 AU, p<0.001), compared to normal subjects (15.0 ± 1.4 AU). MA was significantly decreased in the patients with NTG (20.3 ± 4.6 AU, p<0.001) and POAG (17.7 ± 3.5 AU, p<0.001), compared to normal subjects (29.6 ± 3.6 AU). In the time analysis parameters, Skew, the coefficient of skewness in the blood flow waveform of a beat, was significantly decreased in NTG patients, compared to POAG patients (11.0 ± 2.0AU, 12.6 ± 1.0AU, P=0.007). MV, MT, and MA were significantly correlated to the avg. RNFLT (r=0.55, 0.57 and 0.74 respectively).
Conclusions: :
These results suggest that ocular circulation in the ONH is significantly decreased in NTG and POAG patients, compared with normal subjects. LSFG-NAVI enables us to assess the different hemodynamics in the patients with glaucoma.