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Purpose: To evaluate peripapillary microvascular changes in patients with primary open-angle glaucoma (POAG) after trabeculectomy using optical coherence tomography (OCT) angiography, and to determine the influence of lamina cribrosa (LC) displacement on changes in peripapillary microvasculature., Methods: The peripapillary retinal microvasculature and LC were imaged using OCT angiography and OCT-enhanced depth imaging, respectively. The microvasculature and LC depth (LCD) were measured before, and 1 week, 1 month, and 3 months after trabeculectomy. The microvascular improvement was arbitrarily defined as a reduction >30% of the area of vascular dropout (blue/black areas with <20% vessel density on the color-coded vessel density map). LCD was determined as the mean of vertical distance between the anterior LC surface and a reference plane of Bruch's membrane., Results: Thirty-one eyes of 31 POAG patients were included. At 3 months postoperatively, intraocular pressure (IOP) and LCD were significantly decreased from 26.3 ± 11.8 mm Hg to 12.5 ± 3.6 mm Hg, and 501.1 ± 130.2 μm to 455.8 ± 112.7 μm, respectively (all P < 0.001), compared with baseline. The microvascular improvement was observed in 19 eyes (61.3%) at 3 months after trabeculectomy. The maximal reductions in IOP and LCD were significantly greater in eyes with improved microvasculature compared to eyes without improvement (P = 0.020 and P = 0.005). The microvascular improvement was significantly associated with maximal reduction in LCD (odds ratio, 1.062; P = 0.026)., Conclusions: Trabeculectomy can improve peripapillary retinal microcirculation in patients with POAG. This finding suggests that the reduction of LCD induced by lowering IOP may affect peripapillary microvascular improvement in eyes with POAG.

Purpose: To quantitatively investigate the microstructural properties of the optic nerve (ON) in vivo using diffusion magnetic resonance imaging (dMRI) tractography in an elderly population and to determine the differences between the ON diffusion properties stratified by basic demographics. Methods: We measured fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) of the intraorbital ON in cognitively normal controls selected from the Alzheimer's Disease Neuroimaging Initiative 3 database (n =104; mean age = 73. 8 ± 8.1 years) using dMRI probabilistic tractography and evaluated the correlation between diffusion parameters and demographic factors. Diffusion parameters were measured in 20 equidistant nodes along the tract, and the data from proximal 70% (14 nodes) of the intraorbital ON were averaged. Results: The mean FA of the intraorbital ON was 0.392 ± 0.063, and the mean MD was 1.163 ± 0.165 μm2/s. The mean RD was 0.882 ± 0.152 μm2/s, and the mean AD was 1.693 ± 0.183 μm2/s. The multiple linear regression model showed a negative correlation between FA and age. FA in females was significantly higher than males, whereas RD in female was significantly lower. Conclusions: We measured the diffusion properties of the intraorbital ON using dMRI tractography in an elderly cognitively normal population. The diffusion properties detected by dMRI tractography may substantially reflect the microstructure of the ON.

The aim of this study is to quantitatively investigate the microstructural properties of the optic nerve (ON) in vivo using diffusion tensor imaging (DTI) in patients with unilateral optic atrophy (OA) and to determine their association with retinal nerve fiber layer (RNFL) thickness of the optic nerve head (ONH). Six patients with unilateral OA and 11 control subjects underwent DTI. ONs from ONH to the orbital apex were tracked. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were computed in both ONs and their correlation with RNFL thickness measured using optical coherence tomography was also analyzed. FA of atrophic ON was lower than that of non-affected and control ONs (atrophic [A], 0.136 ± 0.059; non-affected [N], 0.384 ± 0.048; control [C], 0.389 ± 0.053). MD and RD of atrophic ONs were higher than those of non-affected and control ONs (MD, A, 0.988 ± 0.247; N, 0.658 ± 0.058; C, 0.687 ± 0.079; RD, A, 0.920 ± 0.247; N, 0.510 ± 0.054; C, 0.532 ± 0.078). All DTI measures of atrophic ON except for AD showed a significant correlation with RNFL thickness of ONH; FA showed the strongest correlation, followed by RD and MD (FA, R2 = 0.936, P < 0.001; RD, R2 = 0.795, P < 0.001; MD, R2 = 0.655, P = 0.001). This study reports quantitative analysis of the ON using DTI and differences in DTI measures between atrophic and normal ONs. The significant correlation between DTI measures and RNFL thickness suggests the applicability of DTI as a clinical tool to evaluate the ON. [ABSTRACT FROM AUTHOR]