Abstract
Purpose:
To use laser speckle flowgraphy (LSFG) to evaluate differences between normal subjects and patients with normal-tension glaucoma (NTG) in waveform analysis parameters (skew, blowout time (BOT), flow acceleration index (FAI), and acceleration time index (ATI)) of blood flow in the optic nerve head (ONH). Additionally, to evaluate the correlation of these LSFG parameters with an objective examination.
Methods:
78 NTG patients and 22 age-matched normal subjects (59.37 ± 6.65, 57.32 ± 7.42, respectively) were included in this case-control study. We measured ONH circulation with LSFG just after recording intraocular pressure (IOP) and systemic blood pressure. Microcirculation in the capillary area of the ONH was evaluated with LSFG parameters calculated using the equipped software (LSFG Analyzer, ver. 3.0.43.0, Softcare Ltd, Fukuoka, Japan). Average circumpapillary retinal nerve fiber layer thickness (cpRNFLT) was measured with Stratus OCT, and the visual field was examined with a Humphrey Field Analyzer (HFA, 30-2 SITA standard). Eyes with NTG were divided into three groups based on the progression of visual field defects.
Results:
There were no significant differences in IOP or systemic blood pressure between the normal subjects and the NTG patients. In the ONH, the waveform analysis parameters of skew and FAI were significantly lower in the NTG patients compared to the controls (skew: NTG 11.61 ± 1.87 AU, Control 13.11 ± 1.48 AU, p<0.001; FAI: NTG 0.96 ± 0.41 AU; control 2.29 ± 0.67 AU, p<0.001). The parameter of ATI was significantly higher (NTG: 32.37 ± 3.68 AU; control: 29.98 ± 2.14 AU, p=0.004). The data for skew, ATI, and FAI were significantly correlated to the cpRNFLT (r=0.39, -0.31, and 0.70, respectively, p<0.01).
Conclusions:
In the NTG patients, the waveform peak for ONH blood flow shifted to the posterior compared the control subjects. LSFG waveform analysis parameters indicated the level of glaucomatous damage in NTG patients. These results may help the diagnosis of NTG, as well as research on its pathogenesis.
Keywords: 436 blood supply •
628 optic flow •
629 optic nerve