Over 60 million people worldwide are diagnosed with glaucomatous optic neuropathy, which is estimated to be responsible for 8.4 million cases of irreversible blindness globally. Glaucoma is associated with characteristic damage to the optic nerve and patterns of visual field loss which principally involves the loss of retinal ganglion cells (RGCs). At present, intraocular pressure (IOP) presents the only modifiable risk factor for glaucoma, although RGC and vision loss can continue in patients despite well-controlled IOP. This, coupled with the present inability to diagnose glaucoma until relatively late in the disease process, has led to intense investigations towards the development of novel techniques for the early diagnosis of disease. This review outlines our current understanding of the potential mechanisms underlying RGC and axonal loss in glaucoma. Similarities between glaucoma and other neurodegenerative diseases of the central nervous system are drawn before an overview of recent developments in techniques for monitoring RGC health is provided, including recent progress towards the development of RGC specific contrast agents. The review concludes by discussing techniques to assess glaucomatous changes in the brain using MRI and the clinical relevance of glaucomatous-associated changes in the visual centres of the brain.

/pdf/glaucoma-the-retina-and-beyond-37zgnq5sou.pdf

Glaucoma: the retina and beyond.

In order to test the hypothesis that in primary open angle glaucoma (POAG), an important cause of irreversible blindness, a spreading of neurodegeneration occurs through the brain, we performed multimodal MRI and subsequent whole-brain explorative voxelwise analyses in 13 advanced POAG patients and 12 age-matched normal controls (NC). Altered integrity (decreased fractional anisotropy or increased diffusivities) of white matter (WM) tracts was found not only along the visual pathway of POAG but also in nonvisual WM tracts (superior longitudinal fascicle, anterior thalamic radiation, corticospinal tract, middle cerebellar peduncle). POAG patients also showed brain atrophy in both visual cortex and other distant grey matter (GM) regions (frontoparietal cortex, hippocampi and cerebellar cortex), decreased functional connectivity (FC) in visual, working memory and dorsal attention networks and increased FC in visual and executive networks. In POAG, abnormalities in structure and FC within and outside visual system correlated with visual field parameters in the poorer performing eyes, thus emphasizing their clinical relevance. Altogether, this represents evidence that a vision disorder such as POAG can be considered a widespread neurodegenerative condition.

/pdf/structural-and-functional-brain-changes-beyond-visual-system-1bt0h2t3b1.pdf

Structural and functional brain changes beyond visual system in patients with advanced glaucoma.

Glaucoma is not only an eye disease but is also associated with degeneration of brain structures. We now investigated the pattern of visual and non-visual brain structural changes in 25 primary open angle glaucoma (POAG) patients and 25 age-gender-matched normal controls using T1-weighted imaging. MRI images were subjected to volume-based analysis (VBA) and surface-based analysis (SBA) in the whole brain as well as ROI-based analysis of the lateral geniculate nucleus (LGN), visual cortex (V1/2), amygdala and hippocampus. While VBA showed no significant differences in the gray matter volumes of patients, SBA revealed significantly reduced cortical thickness in the right frontal pole and ROI-based analysis volume shrinkage in LGN bilaterally, right V1 and left amygdala. Structural abnormalities were correlated with clinical parameters in a subset of the patients revealing that the left LGN volume was negatively correlated with bilateral cup-to-disk ratio (CDR), the right LGN volume was positively correlated with the mean deviation of the right visual hemifield, and the right V1 cortical thickness was negatively correlated with the right CDR in glaucoma. These results demonstrate that POAG affects both vision-related structures and non-visual cortical regions. Moreover, alterations of the brain visual structures reflect the clinical severity of glaucoma.

Structural brain alterations in primary open angle glaucoma: a 3T MRI study

PURPOSE Patients with Leber hereditary optic neuropathy (LHON) and cone-rod dystrophy (CRD) have central vision loss; but CRD damages the retinal photoreceptor layer, and LHON damages the retinal ganglion cell (RGC) layer. Using diffusion MRI, we measured how these two types of retinal damage affect the optic tract (ganglion cell axons) and optic radiation (geniculo-striate axons). METHODS Adult onset CRD (n = 5), LHON (n = 6), and healthy controls (n = 14) participated in the study. We used probabilistic fiber tractography to identify the optic tract and the optic radiation. We compared axial and radial diffusivity at many positions along the optic tract and the optic radiation. RESULTS In both types of patients, diffusion measures within the optic tract and the optic radiation differ from controls. The optic tract change is principally a decrease in axial diffusivity; the optic radiation change is principally an increase in radial diffusivity. CONCLUSIONS Both photoreceptor layer (CRD) and retinal ganglion cell (LHON) retinal disease causes substantial change in the visual white matter. These changes can be measured using diffusion MRI. The diffusion changes measured in the optic tract and the optic radiation differ, suggesting that they are caused by different biological mechanisms.

/pdf/white-matter-consequences-of-retinal-receptor-and-ganglion-45rkv0jgii.pdf

White matter consequences of retinal receptor and ganglion cell damage.

Early visual deprivation may lead to both abnormal and plastic changes in the visual and other systems of the brain. Such secondary changes in the gray matter of the early blind have been well studied, but not so well in the cerebral white matter whose subtle changes may be revealed by diffusion tensor imaging. The first purpose of this study is to explore the possible changed white matter regions of the early blind in whole brain manners, using voxel‐based analysis (VBA) and tract‐based spatial statistics (TBSS) methods. The second purpose is to investigate the changes of diffusion eigenvalues in the abnormal white matter fiber tracts using tractography based group mapping analysis. From VBA of fractional anisotropy (FA) images, the significant changed white matter regions were the geniculocalcarine tract (GCT) and its adjacent regions. This finding was validated by TBSS method. Then we studied the changes of mean diffusivity (MD), FA, primary (λ1) and transverse diffusivities (λ23) in the GCT using tractography based group mapping analysis. We found the early blind had significantly lower FA (P < 0.0001), higher MD (P = 0.001) and λ23 (P < 0.0001) in the GCT. This pattern of diffusion changes is similar to findings seen in immaturity or axonal degeneration. Thus, we suggest that transneuronal degeneration and/or immaturity may account for the abnormal diffusion changes in the GCT of the early blind. Hum Brain Mapp 2009. © 2007 Wiley‐Liss, Inc.

New Results - Abnormal Diffusion of Cerebral White Matter in Early Blindness

Purpose: To study changes in the morphometric characteristics of the whole brain visual-related cortex in various stages of primary open angle glaucoma (POAG) in vivo.Materials and methods: Thirty POAG patients (nine early stage cases and 21 advanced-late stage cases) and 30 gender-, education-, and age-matched healthy controls were enrolled in the study. Image data were obtained with a T1 weighted three-dimensional magnetization prepared rapid acquisition gradient echo sequence (T1WI 3D MP RAGE). Voxel-based morphometry (VBM) analysis was used to assess regional differences in gray matter (GM) densities on T1WI 3D MP RAGE scans of patients versus controls.Results: Compared with controls, brain regions with GM density changes were not found in the early stage of POAG patients but were found in the advanced-late stage of POAG patients. These changes with GM density reduction were mainly located in the bilateral primary visual cortex (BA17 and BA18), bilateral paracentral lobule (BA5), right precentral gyru...

Voxel-based morphometry of the visual-related cortex in primary open angle glaucoma.

The invention discloses an MRI locating measurement method for human body optic tract shape. A reconstruction technology of locating multi-layers on a cross section is adopted to obtain a clear optic tract image on the obtained MRI high resolution image data; the reconstructed layers are along the long axle directions of optic nerves and can be adjusted by small angles so as to obtain the sagittal oblique image after reconstruction and relevant morphological data parameters of the optic tract are measured according to the image. The method reduces the errors of the morphological data parameters caused by individual shape differences as well as different positions and angles, and displays the integral structure of the optic tract, thereby improving the accuracy, consistency and repetitiveness of the measurement result.

MRI locating measurement method for human body optic tract shape

The invention discloses an MRI positioning measurement method of anteroposterior diameter and left-right diameter of ventriculus quartus cerebri of human bodies. On an MRI high-resolution image, a line parallel to the connecting line between the cross front edge and the rear linkage is drawn through the top of the ventriculus quartus cerebri and is used as a positioning line for reconstructing thecross section; a cross-section image is reconstructed on the positioning line; and the anteroposterior diameter and the left-right diameter of the ventriculus quartus cerebri are measured according to the cross-section image. The invention eliminates errors caused by inclination of heads of people to be measured, reduces the effect factors on the measuring result by measurement scanning personneland improves the accuracy and the repeatability of the measuring result.

MRI positioning measurement method of anteroposterior diameter and left-right diameter of ventriculus quartus cerebri of human bodies

Reduced white matter integrity in primary open-angle glaucoma: a DTI study using tract-based spatial statistics.

Popular Tasks used by Researchers

How can I help with your research?

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

We encountered an error while loading the panel. Please try refreshing the page.

Something went wrong

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

Anyone with the link can view this chat. You can switch it back to private anytime.

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Linping Shi

Author Tools

Chat about Author

Papers

Voxel-based morphometry of the visual-related cortex in primary open angle glaucoma.

MRI locating measurement method for human body optic tract shape

MRI positioning measurement method of anteroposterior diameter and left-right diameter of ventriculus quartus cerebri of human bodies

Reduced white matter integrity in primary open-angle glaucoma: a DTI study using tract-based spatial statistics.