Abstract
To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCT-A). One or both eyes of each subject were imaged for a 3 × 3 mm peripapillary region by swept-source OCT-A (DRI-OCT Triton, Topcon, Japan) and assessed by an automated MATLAB program. OCT-A metrics including circumpapillary vessel density (cpVD) and fractal dimension (cpFD) were compared. Their association with visual field (VF) parameters and retinal nerve fiber layer (RNFL) thickness were determined. Sixty-eight eyes of 51 PACG, 68 eyes of 48 NTG, and 68 eyes of 49 control subjects were cross-sectionally analyzed. NTG eyes had significantly lower global cpVD (52.369 ± 0.781%) compared with PACG eyes (55.389 ± 0.721%, P = 0.004) that had comparable disease severity and average RNFL thickness. Multivariable analysis revealed that, for PACG and NTG eyes, decreased cpVD ([PACG] β = −4.242; CI: −8.120, −0.363 vs [NTG] β = −5.531; CI: −9.472, −1.590) and cpFD ([PACG] β = −8.894;CI: −11.925, −5.864 vs [NTG] β = −12.064; CI: −17.095, −6.932) were associated with decreased RNFL thickness (all P ≤ 0.032); with a stronger association between decrease cpFD and decreased RNFL thickness in NTG eyes (P = 0.028). Decreased cpVD was associated with decrease mean deviation (MD) in NTG eyes (β = −0.707; CI: −1.090, −0.324; P ≤ 0.001) and not associated with the visual field parameters in PACG eyes. Early NTG had lower global cpVD compared with early PACG, despite similar disease severity and average RNFL thickness.
Highlights
To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCTA)
Rao et al.[30] reported that vessel density (VD) in optic disc region in PACG eyes was significantly lower than control eyes, whereas VD in primary angle closure (PAC) with high intraocular pressure (IOP) and thinner superotemporal peripapillary retinal nerve fiber layer (RNFL) thickness was similar to that of the controls
Our results showed a significantly reduced global circumpapillary vessel density (cpVD) in NTG eyes compared with PACG eyes, despite the comparable RNFL thickness and disease severity
Summary
To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCTA). OCT-A metrics including circumpapillary vessel density (cpVD) and fractal dimension (cpFD) were compared Their association with visual field (VF) parameters and retinal nerve fiber layer (RNFL) thickness were determined. Associated with VF defects in a region-specific m anner[15] These suggested that OCT-A may be potentially useful in detecting retinal microvascular change and vascular mechanism of g laucoma[13, 16]. Comparing the microvasculature of PACG eyes (a predominantly IOP-dependent glaucoma subtype) and NTG eyes (a predominantly non-IOP-dependent glaucoma subtype) could reveal the role of vascular mechanisms in the disease pathogenesis, especially at the early stage of the disease in which early vascular and retinal nerve fiber layer (RNFL) changes could be observed. The purpose of the present study was to evaluate peripapillary vasculature between early PACG and early NTG, as well as to compare the strength of associations in OCT-A vascular metrics with structural and functional glaucoma parameters in PACG and NTG
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