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Progress in Retinal and Eye Research Nov 2019Compression of the optic chiasm causes an optic neuropathy that may be associated with reversible visual loss often immediately following surgical decompression. While... (Review)
Review
Compression of the optic chiasm causes an optic neuropathy that may be associated with reversible visual loss often immediately following surgical decompression. While the precise pathogenesis of retinal ganglion cell impairment and eventual death remains poorly understood, a number of putative mechanisms may play a role. In this article we review the evidence supporting various stages of visual loss and recovery in chiasmal compression. These include conduction block, demyelination, ischemic insult, and retrograde and anterograde degeneration. We also describe novel advances in magnetic resonance imaging with specialized modalities such as diffusion tensor imaging have provided further information to explain the underlying mechanism of visual loss. Functional measures including electrophysiology are time-consuming but have shown moderate prognostic ability. Optical coherence tomography has provided novel new biomarkers for predicting outcome following surgical decompression. Both retinal nerve fiber layer thickness and ganglion cell complex thicknesses have shown to have excellent predictive power. Such advances serve to inform patients and clinicians of pre-operative factors that predict the extent of visual recovery following medical or surgical treatment of para-chiasmal lesions.
Topics: Animals; Blindness; Humans; Nerve Compression Syndromes; Nerve Fibers; Optic Chiasm; Optic Nerve Diseases; Recovery of Function; Retinal Ganglion Cells; Tomography, Optical Coherence; Visual Pathways
PubMed: 31202890
DOI: 10.1016/j.preteyeres.2019.06.001 -
Annual Review of Vision Science Sep 2020Binocular vision depends on retinal ganglion cell (RGC) axon projection either to the same side or to the opposite side of the brain. In this article, we review the... (Review)
Review
Binocular vision depends on retinal ganglion cell (RGC) axon projection either to the same side or to the opposite side of the brain. In this article, we review the molecular mechanisms for decussation of RGC axons, with a focus on axon guidance signaling at the optic chiasm and ipsi- and contralateral axon organization in the optic tract prior to and during targeting. The spatial and temporal features of RGC neurogenesis that give rise to ipsilateral and contralateral identity are described. The albino visual system is highlighted as an apt comparative model for understanding RGC decussation, as albinos have a reduced ipsilateral projection and altered RGC neurogenesis associated with perturbed melanogenesis in the retinal pigment epithelium. Understanding the steps for RGC specification into ipsi- and contralateral subtypes will facilitate differentiation of stem cells into RGCs with proper navigational abilities for effective axon regeneration and correct targeting of higher-order visual centers.
Topics: Animals; Axons; Mice; Nerve Regeneration; Optic Chiasm; Retinal Ganglion Cells; Vision, Binocular; Visual Pathways
PubMed: 32396770
DOI: 10.1146/annurev-vision-091517-034306 -
The Canadian Journal of Neurological... Jul 2023Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are common causes of congenital visual impairment. Our primary aim was to investigate the...
BACKGROUND
Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are common causes of congenital visual impairment. Our primary aim was to investigate the prevalence of abnormal neuroimaging features in patients with these disorders in Manitoba, Canada, and compare them with published reports.
METHODS
A retrospective neuroimaging review was performed in patients resident in Manitoba with ONH/SOD.
RESULTS
There were 128 patients ( = 70) with ONH/SOD who had neuroimaging. Their mean age (SD) at the end of the study was 13.2 (7.5) years. Males were significantly more likely to have bilateral ONH and a small optic chiasm size, while females were more likely to have a left ONH and a small left optic chiasm size on neuroimaging ( = 0.049). ONH and small optic chiasm size were seen in most patients on neuroimaging. Absent septum pellucidum was noted in 40%, small pituitary gland size in 28%, neuronal migration disorders (NMD) in 20% (>1 type and bilateral in 13 cases), corpus callosum abnormalities were present in 9%, while olfactory bulbs-tracts and olfactory sulci were absent in 8.6% of cases. Unilateral ONH was not significantly associated with other structural brain abnormalities, while NMD were significantly associated with other midline brain abnormalities including a symmetrically small optic chiasm size.
CONCLUSION
The prevalence of structural neuroimaging abnormalities in our cohort with ONH/SOD was generally in the same range reported in other studies with corpus callosum abnormalities being relatively less common in our study. Bilateral NMD were relatively common among patients with NMD. The association between sex and ONH laterality requires further study.
PubMed: 37492885
DOI: 10.1017/cjn.2023.263 -
European Journal of Ophthalmology Jan 2023Recognising optic chiasmal disease early is important in order to avoid irreversible visual loss and the potential risk of mortality for patients. Yet, there is... (Review)
Review
Recognising optic chiasmal disease early is important in order to avoid irreversible visual loss and the potential risk of mortality for patients. Yet, there is frequently a delay in the initial diagnosis. Whilst the signs of optic chiasmal disease, particularly the perimetric findings, are well documented in the recent literature, the symptoms have been less well reported. Whilst some patients with optic chiasmal disease will be asymptomatic, many will complain of visual symptoms including symptomatic field defects, problems with central vision, difficulty with near tasks, binocular visual disturbances, colour vision disturbances, photophobia, phosphenes, glare, and rarely, oscillopsia and visual hallucinations. Others may have headache or the severe and sudden visual symptoms associated with pituitary apoplexy. The visual symptoms may be vague or non-specific, even when there are significant bitemporal visual field defects. We aim in this review to describe the presenting visual symptoms of optic chiasmal disease, and to illustrate these with selected qualitative descriptions from the literature. Our hope is that this will aid clinicians in eliciting a careful history of the sometimes subtle symptoms that may be present.
Topics: Humans; Optic Chiasm; Vision Disorders; Visual Field Tests; Diagnosis, Differential
PubMed: 36147020
DOI: 10.1177/11206721221125264 -
International Ophthalmology Clinics 2019
Review
Topics: Humans; Magnetic Resonance Imaging; Optic Chiasm; Optic Nerve Diseases; Tomography, Optical Coherence
PubMed: 31233416
DOI: 10.1097/IIO.0000000000000280 -
JAMA Ophthalmology Feb 2015
Topics: Diagnosis, Differential; Glioma; Humans; Ischemia; Magnetic Resonance Imaging; Optic Chiasm; Optic Nerve; Optic Nerve Neoplasms
PubMed: 25474303
DOI: 10.1001/jamaophthalmol.2014.220 -
Journal of Neuro-ophthalmology : the... Mar 2019To describe an unusual case of traumatic globe luxation with optic chiasmal avulsion and review the existing literature on this rare condition for further discussion of... (Review)
Review
BACKGROUND
To describe an unusual case of traumatic globe luxation with optic chiasmal avulsion and review the existing literature on this rare condition for further discussion of mechanisms, diagnosis, and management.
METHODS
Case report and review of existing case reports and case series identified through literature search.
RESULTS
A 28-year-old woman, with no previous medical history, had left globe luxation and optic chiasm avulsion after being stabbed directly into the left orbit with the use of the stiletto high heel of a shoe. Automated visual field testing detected a temporal hemianopia in the unaffected eye despite normal central visual acuity. Chiasmal avulsion was demonstrated by MRI.
CONCLUSIONS
This case suggests that perimetry and MRI should always be considered in traumatic globe luxation to localize the site of injury. Temporal hemianopia in the fellow eye indicates a concomitant chiasmal injury.
Topics: Adult; Eye Enucleation; Eye Injuries, Penetrating; Female; Hemianopsia; Humans; Magnetic Resonance Imaging; Optic Chiasm; Optic Nerve Injuries; Tomography, X-Ray Computed; Trauma Severity Indices; Visual Fields
PubMed: 29901489
DOI: 10.1097/WNO.0000000000000671 -
Journal of Neuro-ophthalmology : the... Sep 2018In evaluating a 3-month-old boy with horizontal nystagmus, brain MRI revealed absence of the optic chiasm. The remainder of the brain was normal in appearance. Achiasma...
In evaluating a 3-month-old boy with horizontal nystagmus, brain MRI revealed absence of the optic chiasm. The remainder of the brain was normal in appearance. Achiasma was confirmed with diffusion tensor imaging and best visualized with optimized probabilistic-based tractography.
Topics: Diffusion Magnetic Resonance Imaging; Follow-Up Studies; Humans; Infant; Male; Optic Chiasm; Optic Nerve Diseases; Visual Acuity
PubMed: 29561327
DOI: 10.1097/WNO.0000000000000650 -
Neuroimaging Clinics of North America Aug 2015Retrochiasmal visual pathways include optic tracts, lateral geniculate nuclei, optic radiations, and striate cortex (V1). Homonymous hemianopsia and field defect... (Review)
Review
Retrochiasmal visual pathways include optic tracts, lateral geniculate nuclei, optic radiations, and striate cortex (V1). Homonymous hemianopsia and field defect variants with relatively normal visual acuity suggest that the lesions involve retrochiasmal pathways. From V1, visual input is projected to higher visual association areas that are responsible for perception of objects, faces, colors, and orientation. Visual association areas are classified into ventral and dorsal pathways. Damage to the ventral stream results in visual object agnosia, prosopagnosia, and achromatopsia. Balint syndrome, visual inattention, and pure alexia are examples of dorsal stream disorders. Posterior cortical atrophy can involve ventral and dorsal streams, often preceding dementia.
Topics: Humans; Neuroimaging; Optic Chiasm; Optic Nerve; Optic Nerve Diseases; Vision Disorders; Visual Pathways
PubMed: 26208417
DOI: 10.1016/j.nic.2015.05.005 -
Journal of Neuro-ophthalmology : the... Sep 2014: A critical review of the literature indicates that idiopathic opticochiasmatic arachnoiditis, once considered an important consideration in patients with otherwise... (Review)
Review
: A critical review of the literature indicates that idiopathic opticochiasmatic arachnoiditis, once considered an important consideration in patients with otherwise unexplained optic atrophy, is not a valid disease entity.
Topics: Arachnoiditis; Humans; Optic Atrophy; Optic Chiasm
PubMed: 25136775
DOI: 10.1097/WNO.0000000000000089