Diffusion Tensor Imaging Detects Microstructural Differences of Visual Pathway in Patients With Primary Open-Angle Glaucoma and Ocular Hypertension

Abstract

Ocular hypertension (OHT), the common situation in adult patients in the outpatients, occurs ∼5% worldwide. However, there are still some practical problems in differentiation of OHT with early primary open-angle glaucoma (POAG) using current standard methods. Application of high resolution diffusion tensor imaging (DTI) enables us to the differentiate axonal architecture of visual pathway between POAG and OHT subjects. Among 32 POAG patients recruited (15 OHT and 14 control subjects), 62.5% of glaucoma were in early stage for the current study. All subjects underwent ophthalmological assessments with standard automated perimetry and optical coherence tomography (OCT). DTI was applied to measure fraction anisotropy (FA) and mean diffusivity (MD) of optic tract (OT), lateral geniculate body (LGN) and optic radiation (OR) using voxel-based analysis. Our data demonstrated that FA values of bilateral OR in POAG were significantly lower in the right or left than that of OHT patients (left OR: 0.51 ± 0.04 vs. 0.54 ± 0.03, p < 0.05; right OR: 0.51 ± 0.05 vs. 0.54 ± 0.03, p < 0.05). In right LGN, MD values were higher in POAG patients compared with OHT subjects (9.81 ± 1.45 vs. 8.23 ± 0.62, p < 0.05). However, no significant difference of all of the DTI parameters was observed between OHT and control subjects. DTI parameters in POAG patients were positively correlated with morphological and functional measurements (p < 0.05). Vertical cup to disc ratio (VCDR) was correlated with ipsilateral FA of OT (p < 0.05), ipsilateral MD of OT (p < 0.05), ipsilateral MD of LGN (p < 0.05), and contralateral MD of OT (p < 0.05). Mean deviation of visual field (MDVF) was correlated with ipsilateral FA of OT (p < 0.05), ipsilateral MD of OT (p < 0.05), and ipsilateral FA of LGN (p < 0.05). Our study demonstrated that DTI can differentiate POAG from OHT subjects in optic pathway, particularly in early POAG, and DTI parameters can quantify the progression of POAG.

The Causal Association Between Obesity and Primary Open-Angle Glaucoma: A Two-Sample Mendelian Randomization Study

“…Primary open-angle glaucoma is the most common type of glaucoma ( Yuan et al, 2013 ). The early clinical manifestations are almost insidious, and visual function may be irreversibly damaged at onset ( Song et al, 2018 ). Therefore, proactively identifying the risk factors for POAG has become the central point of POAG prevention.…”

Transneuronal Degeneration in the Brain During Glaucoma

“…They are sensitive to high-frequency space and transmit red and green color information (Schiller and Malpeli, 1978 ; Hendry and Calkins, 1998 ; Masri et al, 2020 ). Several studies have shown that both the M and P layers of the LGN are damaged in monkey glaucoma models (Dandona et al, 1991 ; Chaturvedi et al, 1993 ; Vickers et al, 1997 ; Weber et al, 2000 ; Yucel et al, 2000 , 2001 ; Sasaoka et al, 2008 ; Ito et al, 2009 , 2011 ; Yan et al, 2017 ), and this conclusion has also been confirmed in human glaucoma patients (Gupta et al, 2006 , 2009 ; Dai et al, 2011 ; Hernowo et al, 2011 ; Shimazawa et al, 2012 ; Chen et al, 2013b ; Lee et al, 2014 ; Wang et al, 2015 , 2016 ; Zhang et al, 2016 ; Ersoz et al, 2017 ; Song et al, 2018 ; Xu et al, 2018 ; Li et al, 2019a ; Kosior-Jarecka et al, 2020 ). Weber et al used a laser-induced chronic glaucoma monkey model to explore changes in size, density, and number of LGN neurons during glaucoma.…”

Multi-contrast magnetic resonance imaging of visual white matter pathways in glaucoma patients

“…Recently, diffusion tensor imaging (DTI) has enabled researchers to investigate tissue abnormalities of visual white matter tracts, such as the optic tract (OT) and optic radiation (OR; Figure 1B), in living humans 4,5 . DTI studies have demonstrated that glaucoma patients show abnormalities in diffusivity measurements, such as fractional anisotropy (FA) 6 , along these tracts [7][8][9][10][11][12][13][14][15][16][17][18] . However, a major limitation is that DTI-based metrics do not directly correlate with specific types of tissue properties, such as axon diameter and myelination 5,[19][20][21][22][23] .…”