Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study

Background: Primary open-angle glaucoma (POAG) patients exhibit widespread white matter (WM) degeneration throughout their visual pathways. Whether this degeneration starts at the pre- or post-geniculate pathways remains unclear. In this longitudinal study, we assess the progression of WM degenerati...

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Main Authors: Shereif Haykal, Nomdo M. Jansonius, Frans W. Cornelissen
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-03-01
Series:Frontiers in Human Neuroscience
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fnhum.2021.630898/full
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spelling doaj-e2e456feb9064a8da6e7d0c1d345a1802021-03-29T04:18:20ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612021-03-011510.3389/fnhum.2021.630898630898Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal StudyShereif Haykal0Nomdo M. Jansonius1Frans W. Cornelissen2Laboratory for Experimental Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, NetherlandsDepartment of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, NetherlandsLaboratory for Experimental Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, NetherlandsBackground: Primary open-angle glaucoma (POAG) patients exhibit widespread white matter (WM) degeneration throughout their visual pathways. Whether this degeneration starts at the pre- or post-geniculate pathways remains unclear. In this longitudinal study, we assess the progression of WM degeneration exhibited by the pre-geniculate optic tracts (OTs) and the post-geniculate optic radiations (ORs) of POAG patients over time, aiming to determine the source and pattern of spread of this degeneration.Methods: Diffusion-weighted MRI scans were acquired for 12 POAG patients and 14 controls at two time-points 5.4 ± 2.1 years apart. Fiber density (FD), an estimate of WM axonal density, was computed for the OTs and ORs of all participants in an unbiased longitudinal population template space. First, FD was compared between POAG patients and the controls at time-point 1 (TP1) and time-point 2 (TP2) independently. Secondly, repeated measures analysis was performed for FD change in POAG patients between the two time-points. Finally, we compared the rate of FD change over time between the two groups.Results: Compared to the controls, POAG patients exhibited significantly lower FD in the left OT at TP1 and in both OTs and the left OR at TP2. POAG patients showed a significant loss of FD between the time-points in the right OT and both ORs, while the left OR showed a significantly higher rate of FD loss in POAG patients compared to the controls.Conclusions: We find longitudinal progression of neurodegenerative WM changes in both the pre- and post-geniculate visual pathways of POAG patients. The pattern of changes suggests that glaucomatous WM degeneration starts at the pre-geniculate pathways and then spreads to the post-geniculate pathways. Furthermore, we find evidence that the trans-synaptic spread of glaucomatous degeneration to the post-geniculate pathways is a prolonged process which continues in the absence of detectable pre-geniculate degenerative progression. This suggests the presence of a time window for salvaging intact post-geniculate pathways, which could prove to be a viable therapeutic target in the future.https://www.frontiersin.org/articles/10.3389/fnhum.2021.630898/fullglaucomawhite matterdiffusion MRIfixel-based analysislongitudinal
collection DOAJ
language English
format Article
sources DOAJ
author Shereif Haykal
Nomdo M. Jansonius
Frans W. Cornelissen
spellingShingle Shereif Haykal
Nomdo M. Jansonius
Frans W. Cornelissen
Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
Frontiers in Human Neuroscience
glaucoma
white matter
diffusion MRI
fixel-based analysis
longitudinal
author_facet Shereif Haykal
Nomdo M. Jansonius
Frans W. Cornelissen
author_sort Shereif Haykal
title Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
title_short Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
title_full Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
title_fullStr Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
title_full_unstemmed Progression of Visual Pathway Degeneration in Primary Open-Angle Glaucoma: A Longitudinal Study
title_sort progression of visual pathway degeneration in primary open-angle glaucoma: a longitudinal study
publisher Frontiers Media S.A.
series Frontiers in Human Neuroscience
issn 1662-5161
publishDate 2021-03-01
description Background: Primary open-angle glaucoma (POAG) patients exhibit widespread white matter (WM) degeneration throughout their visual pathways. Whether this degeneration starts at the pre- or post-geniculate pathways remains unclear. In this longitudinal study, we assess the progression of WM degeneration exhibited by the pre-geniculate optic tracts (OTs) and the post-geniculate optic radiations (ORs) of POAG patients over time, aiming to determine the source and pattern of spread of this degeneration.Methods: Diffusion-weighted MRI scans were acquired for 12 POAG patients and 14 controls at two time-points 5.4 ± 2.1 years apart. Fiber density (FD), an estimate of WM axonal density, was computed for the OTs and ORs of all participants in an unbiased longitudinal population template space. First, FD was compared between POAG patients and the controls at time-point 1 (TP1) and time-point 2 (TP2) independently. Secondly, repeated measures analysis was performed for FD change in POAG patients between the two time-points. Finally, we compared the rate of FD change over time between the two groups.Results: Compared to the controls, POAG patients exhibited significantly lower FD in the left OT at TP1 and in both OTs and the left OR at TP2. POAG patients showed a significant loss of FD between the time-points in the right OT and both ORs, while the left OR showed a significantly higher rate of FD loss in POAG patients compared to the controls.Conclusions: We find longitudinal progression of neurodegenerative WM changes in both the pre- and post-geniculate visual pathways of POAG patients. The pattern of changes suggests that glaucomatous WM degeneration starts at the pre-geniculate pathways and then spreads to the post-geniculate pathways. Furthermore, we find evidence that the trans-synaptic spread of glaucomatous degeneration to the post-geniculate pathways is a prolonged process which continues in the absence of detectable pre-geniculate degenerative progression. This suggests the presence of a time window for salvaging intact post-geniculate pathways, which could prove to be a viable therapeutic target in the future.
topic glaucoma
white matter
diffusion MRI
fixel-based analysis
longitudinal
url https://www.frontiersin.org/articles/10.3389/fnhum.2021.630898/full
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