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Frontiers in Neuroscience 2023Glaucoma is the first major category of irreversible blinding eye illnesses worldwide. Its leading cause is the death of retinal ganglion cells and their axons, which... (Review)
Review
Glaucoma is the first major category of irreversible blinding eye illnesses worldwide. Its leading cause is the death of retinal ganglion cells and their axons, which results in the loss of vision. Research indicates that glaucoma affects the optic nerve and the whole visual pathway. It also reveals that degenerative lesions caused by glaucoma can be found outside the visual pathway. Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that can investigate the complete visual system, including alterations in the optic nerve, optic chiasm, optic tract, lateral geniculate nuclear, and optic radiation. In order to provide a more solid foundation for the degenerative characteristics of glaucoma, this paper will discuss the standard diagnostic techniques for glaucoma through a review of the literature, describe the use of DTI technology in glaucoma in humans and animal models, and introduce these techniques. With the advancement of DTI technology and its coupling with artificial intelligence, DTI represents a potential future for MRI technology in glaucoma research.
PubMed: 36816120
DOI: 10.3389/fnins.2023.1125638 -
Frontiers in Neurology 2016Blast has been the leading cause of injury, particularly traumatic brain injury and visual system injury, in combat operations in Iraq and Afghanistan. We determined the...
Blast has been the leading cause of injury, particularly traumatic brain injury and visual system injury, in combat operations in Iraq and Afghanistan. We determined the effect of shock tube-generated primary blast on retinal electrophysiology and on retinal and brain optic tract histopathology in a rat model. The amplitude of a- and b-waves on the electroretinogram (ERG) for both right and left eyes were measured prior to a battlefield simulation Friedlander-type blast wave and on 1, 7, and 14 days thereafter. Histopathologic findings of the right and left retina and the right and left optic tracts (2.8 mm postoptic chiasm) were evaluated 14 days after the blast. For two experiments in which the right eye was oriented to the blast, the amplitude of ERG a- and b-waves at 7 days post blast on the right side but not on the left side was diminished compared to that of sham animals (P = 0.005-0.01) Histopathologic injury scores at 14 days post blast for the right retina but not the left retina were higher than for sham animals (P = 0.01), and histopathologic injury scores at 14 days for both optic tracts were markedly higher than for shams (P < 0.0001). Exposure of one eye to a blast wave, comparable to that causing human injury, produced injury to the retina as determined by ERG and histopathology, and to both postchiasmatic optic tracts as determined by histopathology. This model may be useful for analyzing the effect of therapeutic interventions on retinal damage due to primary blast waves.
PubMed: 27199884
DOI: 10.3389/fneur.2016.00059 -
Neuron Aug 2020At various stages of the visual system, visual responses are modulated by arousal. Here, we find that in mice this modulation operates as early as in the first synapse...
At various stages of the visual system, visual responses are modulated by arousal. Here, we find that in mice this modulation operates as early as in the first synapse from the retina and even in retinal axons. To measure retinal activity in the awake, intact brain, we imaged the synaptic boutons of retinal axons in the superior colliculus. Their activity depended not only on vision but also on running speed and pupil size, regardless of retinal illumination. Arousal typically reduced their visual responses and selectivity for direction and orientation. Recordings from retinal axons in the optic tract revealed that arousal modulates the firing of some retinal ganglion cells. Arousal had similar effects postsynaptically in colliculus neurons, independent of activity in the other main source of visual inputs to the colliculus, the primary visual cortex. These results indicate that arousal modulates activity at every stage of the mouse visual system.
Topics: Animals; Arousal; Axons; Locomotion; Mice; Neurons; Optic Tract; Orientation, Spatial; Presynaptic Terminals; Retinal Ganglion Cells; Superior Colliculi; Visual Pathways; Wakefulness
PubMed: 32445624
DOI: 10.1016/j.neuron.2020.04.026 -
Journal of Neurosurgery. Case Lessons Nov 2022Chiasmatic and optic track lymphoma as the primary lesion of the central nervous system (CNS) is extremely rare.
BACKGROUND
Chiasmatic and optic track lymphoma as the primary lesion of the central nervous system (CNS) is extremely rare.
OBSERVATIONS
The authors report a case of a previously healthy 62-year-old woman who presented with quick and progressive visual impairment leading to bilateral blindness. Brain imaging studies suggested glioma or lymphoma of the chiasm and the posterior visual pathway. Postoperative examination revealed low-grade malignant B-cell lymphoma. No evidence of extracranial lymphoma was found, so a final diagnosis of primary CNS lymphoma (PCNSL) was made.
LESSONS
To the authors' knowledge, PCNSL confined to the optic chiasm has rarely been reported in nonimmunocompromised patients. The present case of lymphoma affecting the optic chiasm and optic tract is extremely rare.
PubMed: 36377128
DOI: 10.3171/CASE22340 -
Neurology India 2022Many potential causes of optic nerve inflammation exist, including typical and atypical causes, which require different management strategies.
BACKGROUND
Many potential causes of optic nerve inflammation exist, including typical and atypical causes, which require different management strategies.
OBJECTIVE
The objective of this study is to identify red flags that help differentiate typical from atypical optic neuritis (ON).
MATERIALS AND METHODS
This prospective study included 66 patients (100 eyes) with immune-mediated ON from January 2016 to June 2019, carefully excluding the nonimmune causes. The clinico-radiological features, investigations, therapy, and outcome were analyzed.
RESULTS
We evaluated 33 cases each of typical and atypical ON. The typical group included 29 idiopathic ON and four associated with multiple sclerosis. Atypical ON included 19 neuromyelitis optica (NMO), seven MOG-associated ON (MOG-ON), and others due to Sjogren's syndrome, granulomatous polyangiitis, sarcoidosis, and IgG4 disease. Atypical ON occurred significantly and more frequently with extremes of ages (<10 or >70 years), bilateral simultaneous or severe vision loss with early disc pallor, multiple attacks, symptoms/neuro-imaging indicating non-MS disease e.g., long segment ON/myelitis, large confluent lesions, the involvement of optic tract, chiasma, area postrema or diencephalon, and (pachy) meningitis. Systemic involvement and poor outcomes despite steroids and second-line immunosuppression were observed more often in the atypical ON.
CONCLUSIONS
The red flags indicating atypical ON are onset at extremes of age, multiple attacks, bilateral simultaneous or severe to very severe vision loss, early disc pallor, neurological symptoms, or imaging abnormalities suggesting non-MS disease, systemic involvement, and poor steroid responsiveness. The awareness might help the clinician promptly identify and escalate therapy to ensure a better outcome.
Topics: Aged; Humans; Autoantibodies; Myelin-Oligodendrocyte Glycoprotein; Neuromyelitis Optica; Optic Neuritis; Pallor; Prospective Studies; Vision Disorders
PubMed: 36352598
DOI: 10.4103/0028-3886.359189 -
Cell Reports Mar 2023Building precise neural circuits necessitates the elimination of axonal projections that have inaccurately formed during development. Although axonal pruning is a...
Building precise neural circuits necessitates the elimination of axonal projections that have inaccurately formed during development. Although axonal pruning is a selective process, how it is initiated and controlled in vivo remains unclear. Here, we show that trans-axonal signaling mediated by the cell surface molecules Glypican-3, Teneurin-3, and Latrophilin-3 prunes misrouted retinal axons in the visual system. Retinotopic neuron transplantations revealed that pioneer ventral axons that elongate first along the optic tract instruct the pruning of dorsal axons that missort in that region. Glypican-3 and Teneurin-3 are both selectively expressed by ventral retinal ganglion cells and cooperate for correcting missorted dorsal axons. The adhesion G-protein-coupled receptor Latrophilin-3 signals along dorsal axons to initiate the elimination of topographic sorting errors. Altogether, our findings show an essential function for Glypican-3, Teneurin-3, and Latrophilin-3 in topographic tract organization and demonstrate that axonal pruning can be initiated by signaling among axons themselves.
Topics: Glypicans; Visual Pathways; Axons; Retinal Ganglion Cells; Retina
PubMed: 36857189
DOI: 10.1016/j.celrep.2023.112192 -
Brain : a Journal of Neurology Dec 2022The anterior optic pathway is one of the preferential sites of involvement in CNS inflammatory demyelinating diseases, such as multiple sclerosis and neuromyelitis...
The anterior optic pathway is one of the preferential sites of involvement in CNS inflammatory demyelinating diseases, such as multiple sclerosis and neuromyelitis optica, with optic neuritis being a common presenting symptom. What is more, optic nerve involvement in these diseases is often subclinical, with optical coherence tomography demonstrating progressive neuroretinal thinning in the absence of optic neuritis. The pathological substrate for these findings is poorly understood and requires investigation. We had access to post-mortem tissue samples of optic nerves, chiasms and tracts from 29 multiple sclerosis (mean age 59.5, range 25-84 years; 73 samples), six neuromyelitis optica spectrum disorders (mean age 56, range 18-84 years; 22 samples), six acute disseminated encephalomyelitis (mean age 25, range 10-39 years; 12 samples) cases and five non-neurological controls (mean age 55.2, range 44-64 years; 16 samples). Formalin-fixed paraffin-embedded samples were immunolabelled for myelin, inflammation (microglial/macrophage, T- and B-cells, complement), acute axonal injury and astrocytes. We assessed the extent and distribution of these markers along the anterior optic pathway for each case in all compartments (i.e. parenchymal, perivascular and meningeal), where relevant. Demyelinated plaques were classified as active based on established criteria. In multiple sclerosis, demyelination was present in 82.8% of cases, of which 75% showed activity. Microglia/macrophage and lymphocyte inflammation were frequently found both in the parenchymal and meningeal compartments in non-demyelinated regions. Acute axonal injury affected 41.4% of cases and correlated with extent of inflammatory activity in each compartment, even in cases that died at advanced age with over 20 years of disease duration. An antero-posterior gradient of anterior optic pathway involvement was observed with optic nerves being most severely affected by inflammation and acute axonal injury compared with the optic tract, where a higher proportion of remyelinated plaques were seen. In neuromyelitis optica spectrum disorder, cases with a history of optic neuritis had extensive demyelination and lost aquaporin-4 reactivity. In contrast, those without prior optic neuritis did not have demyelination but rather diffuse microglial/macrophage, T- and B-lymphocyte inflammation in both parenchymal and meningeal compartments, and acute axonal injury was present in 75% of cases. Acute demyelinating encephalomyelitis featured intense inflammation, and perivenular demyelination in 33% of cases. Our findings suggest that chronic inflammation is frequent and leads to neurodegeneration in multiple sclerosis and neuromyelitis optica, regardless of disease stage. The chronic inflammation and subsequent neurodegeneration occurring along the optic pathway broadens the plaque-centred view of these diseases and partly explains the progressive neuroretinal changes observed in optic coherence tomography studies.
Topics: Humans; Adult; Middle Aged; Aged; Aged, 80 and over; Adolescent; Young Adult; Child; Neuromyelitis Optica; Optic Nerve; Optic Neuritis; Multiple Sclerosis; Inflammation
PubMed: 35134111
DOI: 10.1093/brain/awac030 -
Journal of Neurosurgery. Pediatrics May 2018OBJECTIVE Tumor-related edema of the optic tract (EOT) corresponds to a preferential posterior distribution of peritumoral edema along the white matter tract of the...
OBJECTIVE Tumor-related edema of the optic tract (EOT) corresponds to a preferential posterior distribution of peritumoral edema along the white matter tract of the visual system. To date, the consequences of EOT have never been evaluated specifically in the pediatric population. In this study, the authors attempted to identify clinical and radiological features associated with the development of EOT and the specific influence of this edema on visual function. METHODS A retrospective review was performed of data collected from patients younger than 18 years who underwent surgery for a tumor in the sellar region at the authors' institution between January 2005 and January 2016. Data were collected on patient characteristics, ophthalmological evaluations, and neuroimaging findings. To evaluate and compare visual function impairment, ophthalmological data were converted to a global visual function score, which took into account visual acuity, visual field evaluations, and laterality deficiencies. The visual acuity score was defined according to the International Classification of Diseases, 10th Revision. Visual field deficiencies were converted to a score of 0-2. Two opposing groups were then distinguished according to the presence or absence of EOT. Visual acuity, visual field results, and global scores were compared between groups before and after treatment. RESULTS Twenty-six patients were included in the study: 17 patients with craniopharyngioma, 3 patients with pilocytic astrocytoma, 2 patients with ganglioglioma, 2 patients with germ cell tumor, 1 patient with macroprolactinoma, and 1 patient with Rathke's cleft cyst. There were 11 children in the group with edema and 15 children in the group without edema. None of the following criteria were statistically different between the 2 groups: age, sex, clinical symptoms at presentation (endocrine deficiency or intracranial hypertension signs), incidence of hydrocephalus, compression of the optic tracts and mass effect on the optic chiasm, tumor size and localization, presence of intratumoral cysts, treatment, type of tumor, or recurrence. The median global visual function and visual acuity scores were not significantly different between the groups either at presentation or at final evaluation. The visual field score was lower (i.e., more deficiency) in the group with edema than in the group without edema (p < 0.05); 89% of the patients with edema had severe or mild visual field impairment versus only 40% of the patients without edema. At the final examination after treatment, the visual field scores were not different between the 2 groups. Although not significant, the number of patients with optic disc pallor was greater in the group without edema both at diagnosis and at final examination. CONCLUSIONS This study confirms that EOT in the context of sellar region tumor in children is not necessarily associated with a less-favorable visual prognosis.
Topics: Astrocytoma; Brain Edema; Brain Neoplasms; Child; Craniopharyngioma; Female; Ganglioglioma; Humans; Magnetic Resonance Imaging; Male; Neoplasms, Germ Cell and Embryonal; Optic Tract; Pituitary Neoplasms; Retrospective Studies; Treatment Outcome; Vision Disorders; Visual Acuity; Visual Fields
PubMed: 29498601
DOI: 10.3171/2017.11.PEDS17526 -
Biology Mar 2022Glaucoma is a group of ophthalmologic conditions characterized by progressive retinal ganglion cell death, optic nerve degeneration, and irreversible vision loss. While... (Review)
Review
Glaucoma is a group of ophthalmologic conditions characterized by progressive retinal ganglion cell death, optic nerve degeneration, and irreversible vision loss. While intraocular pressure is the only clinically modifiable risk factor, glaucoma may continue to progress at controlled intraocular pressure, indicating other major factors in contributing to the disease mechanisms. Recent studies demonstrated the feasibility of advanced diffusion magnetic resonance imaging (dMRI) in visualizing the microstructural integrity of the visual system, opening new possibilities for non-invasive characterization of glaucomatous brain changes for guiding earlier and targeted intervention besides intraocular pressure lowering. In this review, we discuss dMRI methods currently used in visual system investigations, focusing on the eye, optic nerve, optic tract, subcortical visual brain nuclei, optic radiations, and visual cortex. We evaluate how conventional diffusion tensor imaging, higher-order diffusion kurtosis imaging, and other extended dMRI techniques can assess the neuronal and glial integrity of the visual system in both humans and experimental animal models of glaucoma, among other optic neuropathies or neurodegenerative diseases. We also compare the pros and cons of these methods against other imaging modalities. A growing body of dMRI research indicates that this modality holds promise in characterizing early glaucomatous changes in the visual system, determining the disease severity, and identifying potential neurotherapeutic targets, offering more options to slow glaucoma progression and to reduce the prevalence of this world's leading cause of irreversible but preventable blindness.
PubMed: 35336827
DOI: 10.3390/biology11030454 -
Brain Tumor Research and Treatment Apr 2022Optic pathway glioma (OPG) is a rare tumor located in optic nerve, optic tract, or optic chiasm. Treatment options for OPG include surgery, radiation therapy (RT), and... (Review)
Review
Optic pathway glioma (OPG) is a rare tumor located in optic nerve, optic tract, or optic chiasm. Treatment options for OPG include surgery, radiation therapy (RT), and chemotherapy. Although RT may provide favorable long-term outcomes in manner of either adjuvant or salvage aim, chemotherapy-first approach is increasingly performed due to possible late effects of RT. Proton beam RT may allow normal tissue sparing of radiation exposure compared to conventional X-ray treatment. Therefore, proton beam RT is expected to reduce complications from RT. This review discusses the recent updates on oncologic outcomes of OPG, late toxicities following RT, and compares the outcomes between X-ray treatment and proton beam RT.
PubMed: 35545828
DOI: 10.14791/btrt.2022.0003