Correlation between laser speckle flowgraphy and optical coherence tomography angiography measurements in normal and glaucomatous eyes

Abstract

Purpose: To investigate the relationship between laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA) measurements of the peripapillary retina and optic nerve head (ONH) in normal eyes and eyes with primary open-angle glaucoma (POAG).

Patients and methods: One eye from each of 46 normal subjects and mild and moderate/advanced POAG patients were included. ONH blood flow acquired by LSFG, circumpapillary vessel density (cpVD, a 250 μm-wide elliptical annulus around the optic disc), and intra-papillary vessel density (ipVD, a 1.5×1.5 mm scan field) acquired by OCTA were measured. Their values were compared among normal controls and patients at each stage of glaucoma using one-way ANOVA, and the correlation between measurements obtained by the two methods was examined by univariate regression analysis.

Results: ONH tissue blood flow, tissue mean blur rate (MBR-T), and cpVD in the outer layer of the retina significantly decreased with the progression of glaucoma stage, although the latter showed no significant difference between normal subjects and mild-stage glaucoma patients. MBR-T was significantly correlated with cpVD, but not with ipVD, in the retinal outer layer.

Conclusion: A correlation was found only between MBR-T and cpVD in the retinal outer layer. A difference in MBR-T, but not in cpVD, was detected between normal controls and mild glaucoma patients.

Keywords: blood flow; laser speckle flowgraphy; optic nerve head; optical coherent tomography angiography.

Figure 1

(A) ONH blood flow acquired by LSFG. “1” represents region of interest inside ONH. (B) The black area shows MBR-T and the white area shows MBR-V. (C) CpVD “area a” represents a vascular density of 250-μm-wide elliptical annulus around the optic disc. IpVD “area b” represents a vascular density of 1.5×1.5-mm scan field centered on the ONH. Abbreviations: ONH, optic nerve head; LSFG, laser speckle flowgraphy; MBR-T, tissue mean blur rate; MBR-V, vascular mean blur rate; cpVD, circumpapillary vessel density; ipVD, intra-papillary vessel density.

Figure 2

(A) ONH tissue blood flow (MBR-T, mean ± standard error) changes in normal subjects and patients in each glaucoma stage. P<0.001 (one-way ANOVA), *P<0.01 (Dunnett’s test). (B) Retinal outer layer cpVD changes (mean ± standard error) in each glaucoma stage. P=0.02 (one-way ANOVA), *P<0.01 (Dunnett’s test). Abbreviations: n.s, not significant; ONH, optic nerve head; MBR-T, tissue mean blur rate; cpVD, circumpapillary vessel density.

Figure 3

Correlation between retinal outer layer cpVD and MBR-T. P=0.0005, r=0.49 (univariate regression analysis). Abbreviations: MBR-T, tissue mean blur rate; cpVD, circumpapillary vessel density.