DEVELOPMENT OF THE VISUAL PATHWAY: OPTIC CHIASM

OBJECT Visual impairments are the most common objective manifestations of suprasellar lesions. Diffusion tensor imaging (DTI) is a noninvasive MRI modality that depicts the subcortical white matter tracts in vivo. In this study the authors tested the value of visual pathway tractography in comparison with visual field and visual acuity analyses. METHODS This prospective study consisted of 25 patients with progressive visual impairment due to suprasellar mass lesions and 6 control patients with normal vision without such lesions. Visual acuity, visual field, and the optic fundus were examined preoperatively and repeated 1 week and 3 months after surgery. Visual pathway DTI tractography was performed preoperatively, intraoperatively immediately after tumor resection, and 1 week and 3 months after surgery. RESULTS In the control group, pre- and postoperative visual status were normal and visual pathway tractography revealed fibers crossing the optic chiasm without any alteration. In patients with suprasellar lesions, vision improved in 24 of 25. The mean distance between optic tracts in tractography decreased after tumor resection and detectable fibers crossing the optic chiasm increased from 12% preoperatively to 72% postoperatively 3 months after tumor resection, and undetectable fibers crossing the optic chiasm decreased from 88% preoperatively to 27% postoperatively 3 months after tumor resection. Visual improvement after tumor removal 1 week and 3 months after surgery was significantly correlated with the distance between optic tracts in intraoperative tractography (p < 0.01). CONCLUSIONS Visual pathway DTI tractography appears to be a promising adjunct to the standard clinical and paraclinical visual examinations in patients with suprasellar mass lesions. The intraoperative findings, in particular the distance between optic tract fibers, can predict visual outcome after tumor resection. Furthermore, postoperative application of this technique may be useful in following anterior optic pathway recovery.

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A VEP study of the visual pathway function in compressive lesions of the optic chiasm. Full-field versus half-field stimulation

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section ◽

10.1016/0168-5597(92)90002-s ◽

1992 ◽

Vol 84 (3) ◽

pp. 209-218 ◽

Cited By ~ 12

Author(s):

Jelka Brecelj

Keyword(s):

Visual Pathway ◽

Optic Chiasm ◽

Field Stimulation ◽

Full Field ◽

Field Versus ◽

Pathway Function

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Congenital absence of optic chiasm: demonstration of an uncrossed visual pathway using monocular flash visual evoked potentials

Documenta Ophthalmologica ◽

10.1007/s10633-006-9005-1 ◽

2006 ◽

Vol 113 (1) ◽

pp. 1-4 ◽

Cited By ~ 8

Author(s):

Malcolm C. Brown ◽

Caroline L. Southern ◽

Arangasamy Anbarasu ◽

Stephen B. Kaye ◽

Anthony C. Fisher ◽

...

Keyword(s):

Evoked Potentials ◽

Visual Evoked Potentials ◽

Visual Pathway ◽

Optic Chiasm ◽

Congenital Absence ◽

Flash Visual Evoked Potentials ◽

Visual Evoked

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Changes in fiber organization within the chiasmatic region of mammals

Visual Neuroscience ◽

10.1017/s0952523800001772 ◽

1992 ◽

Vol 9 (6) ◽

pp. 527-533 ◽

Cited By ~ 21

Author(s):

Benjamin E. Reese ◽

Gary E. Baker

Keyword(s):

Optic Nerve ◽

Optic Tract ◽

Visual Pathway ◽

Optic Chiasm ◽

Retinal Surface ◽

Classical View ◽

The Difference ◽

Fiber Organization ◽

Sensory Surface ◽

Retinotopic Map

AbstractIntroductionClassical views of the optic chiasm maintain four propositions about the retinofugal pathways: (1) each optic nerve contains a retinotopic representation of its respective retinal surface; (2) this retinotopic map in the nerve is the basis for the subsequent segregation of the decussating from the non-decussating fibers; (3) this retinotopy in the nerve is also the basis for the presence of retinotopy found within the half-retinal maps in the optic tracts; and (4) the half-retinal maps from each optic nerve are brought together within the chiasm to yield a unified, binocularly congruent, map in the optic tract (Brodal, 1969; DukeElder, 1961; Polyak, 1957; Wolff, 1940). The appeal of this classical view is in its simplicity, based on the assumption that the retinofugal pathway should replicate the sensory surface along its course. We now know that each of these four propositions is incorrect, and that the error is not one simply of degree or extent (Guillery, 1982, 1991). Rather, the above description of the visual pathway is fundamentally flawed because it has failed to take into account the constraints under which the pathway develops. We shall first consider the evidence for rejecting the classical view, from recent studies on the organization of the retinofugal pathway in adult animals and on the development of that organization. We shall then describe three transformations in the fiber order which all occur in the chiasmatic region, two of which were only recently recognized, and for which we must account.Observations from adult organizationThe difference in the fiber order in the optic nerve and tract

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When is a control not a control? Reactive microglia occur throughout the control contralateral visual pathway in experimental glaucoma

10.1101/853275 ◽

2019 ◽

Cited By ~ 1

Author(s):

James R Tribble ◽

Eirini Kokkali ◽

Amin Otmani ◽

Flavia Plastino ◽

Emma Lardner ◽

...

Keyword(s):

Optic Nerve ◽

Animal Models ◽

Ganglion Cell ◽

Retinal Ganglion Cell ◽

Internal Control ◽

Visual Pathway ◽

Optic Chiasm ◽

Retinal Ganglion ◽

Reactive Microglia ◽

Contralateral Eye

AbstractPurposeAnimal models show retinal ganglion cell injuries that replicate features of glaucoma and the contralateral eye is commonly used as an internal control. There is significant cross-over of retinal ganglion cell axons from the ipsilateral to the contralateral side at the level of the optic chiasm which may confound findings when damage is restricted to one eye. The effect of unilateral glaucoma on neuroinflammatory damage to the contralateral visual pathway has largely been unexplored.MethodsOcular hypertensive glaucoma was induced unilaterally or bilaterally in the rat and retinal ganglion cell neurodegenerative events were assessed. Neuroinflammation was quantified in the retina, optic nerve head, optic nerve, lateral geniculate nucleus, and superior colliculus by high resolution imaging, and in the retina by flow cytometry and protein arrays.ResultsFollowing ocular hypertensive stress, peripheral monocytes enter the retina, and microglia become reactive. This effect is more marked in animals with bilateral ocular hypertensive glaucoma. In rats where glaucoma was induced unilaterally there was significant microglia activation in the contralateral (control) eye. Microglial activation extended into the optic nerve and terminal visual thalami, where it was similar across hemispheres irrespective of whether ocular hypertension was unilateral or bilateral.ConclusionsThese data suggest that caution is warranted when using the contralateral eye as control in unilateral models of glaucoma.Translational RelevanceUse of a contralateral eye as a control may confound discovery of human relevant mechanism and treatments in animal models. We also identify neuroinflammatory protein responses that warrant further investigation as potential disease modifiable targets.

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Ganglioglioma of the Optic Chiasm: Case Report and Review of the Literature

Neurosurgery ◽

10.1227/00006123-199006000-00021 ◽

1990 ◽

Vol 26 (6) ◽

pp. 1042-1045 ◽

Cited By ~ 22

Author(s):

Jonathan Chilton ◽

Michael R. Caughron ◽

John J. Kepes

Keyword(s):

Case Report ◽

Visual Pathway ◽

Optic Chiasm ◽

Review Of The Literature ◽

Histological Criteria

Abstract We describe a case of ganglioglioma of the optic chiasm and tract in a 33-year-old man. Review of the literature discloses only seven cases of tumors of the anterior visual pathway that meet the histological criteria for such neoplasms. A detailed histological description of our case and a review of the literature is provided.

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Patterns of individual variation in visual pathway structure and function in the sighted and blind

10.1101/065441 ◽

2016 ◽

Author(s):

Geoffrey K. Aguirre ◽

Ritobrato Datta ◽

Noah C. Benson ◽

Sashank Prasad ◽

Samuel G. Jacobson ◽

...

Keyword(s):

Fractional Anisotropy ◽

Individual Variation ◽

Diffusion Tensor ◽

Anatomical Variation ◽

Visual Pathway ◽

Optic Chiasm ◽

Brain Anatomy ◽

Lateral Geniculate ◽

Congenitally Blind ◽

The Brain

AbstractMany structural and functional brain alterations accompany blindness, with substantial individual variation in these effects. In normally sighted people, there is correlated individual variation in some visual pathway structures. Here we examined if the changes in brain anatomy produced by blindness alter the patterns of anatomical variation found in the sighted. We derived eight measures of central visual pathway anatomy from a structural image of the brain from 59 sighted and 53 blind people. These measures showed highly significant differences in mean size between the sighted and blind cohorts. When we examined the measurements across individuals within each group we found three clusters of correlated variation, with V1 surface area and pericalcarine volume linked, and independent of the thickness of V1 cortex. These two clusters were in turn relatively independent of the volumes of the optic chiasm and lateral geniculate nucleus. This same pattern of variation in visual pathway anatomy was found in the sighted and the blind. Anatomical changes within these clusters were graded by the timing of onset of blindness, with those subjects with a post-natal onset of blindness having alterations in brain anatomy that were intermediate to those seen in the sighted and congenitally blind. Many of the blind and sighted subjects also contributed functional MRI measures of cross-modal responses within visual cortex, and a diffusion tensor imaging measure of fractional anisotropy within the optic radiations and the splenium of the corpus callosum. We again found group differences between the blind and sighted in these measures. The previously identified clusters of anatomical variation were also found to be differentially related to these additional measures: across subjects, V1 cortical thickness was related to cross-modal activation, and the volume of the optic chiasm and lateral geniculate was related to fractional anisotropy in the visual pathway. Our findings show that several of the structural and functional effects of blindness may be reduced to a smaller set of dimensions. It also seems that the changes in the brain that accompany blindness are on a continuum with normal variation found in the sighted.

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Bilateral Blindness Due to Left Fronto-Temporal Lobe Glioblastoma Multiforme

Journal of Nepalgunj Medical College ◽

10.3126/jngmc.v18i1.35224 ◽

2020 ◽

Vol 18 (1) ◽

pp. 107-110

Author(s):

Bikram Bahadur Thapa ◽

Joshan Neupane ◽

Sunil Moktan

Keyword(s):

Glioblastoma Multiforme ◽

Poor Prognosis ◽

Vision Loss ◽

Body Movement ◽

Visual Pathway ◽

Optic Chiasm ◽

Direct Compression ◽

Mri Brain ◽

Hearing Difficulty ◽

Primary Malignant Brain Tumor

Introduction: Glioblastoma multiforme is the most common primary malignant brain tumor, with a very poor prognosis. Direct compression of any structure in the visual pathway or chronic papilloedema is the cause of loss of vision in these patients. Case Report: 30 years old male from Dailekh was brought by his elder brother with the complaint of complete vision loss in both eyes for 45 days. He also had hearing difficulty on right side, headache, right sided weakness and abnormal body movement. His Visual acuity was no perception of Light in both eyes. Pupil was mid-dilated and not reacting to light. Fundus examination revealed bilateral Pallid disc edema. MRI brain revealed left fronto-temporal GBM compressing optic chiasm. Neurosurgical consultation was obtained and counseling was done regarding disease and its treatment. Due to poor prognosis and poverty patient choose palliative conservative treatment. Conclusion: This case highlights the possibility of bilateral Blindness in unilateral GBM. GBM has very poor outcome even after treatment.

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