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Hemianopsia, or hemianopia, is a loss of vision or blindness (anopsia) in half the visual field, usually on one side of the vertical midline. The most common causes of this damage are stroke, brain tumor, and trauma.[1]
This article deals only with permanent hemianopsia, and not with transitory or temporary hemianopsia, as identified by William Wollaston PRS in 1824.[2] Temporary hemianopsia can occur in the aura phase of migraine.
A homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes. The visual images that we see to the right side travel from both eyes to the left side of the brain, while the visual images we see to the left side in each eye travel to the right side of the brain. Therefore, damage to the right side of the posterior portion of the brain or right optic tract can cause a loss of the left field of view in both eyes. Likewise, damage to the left posterior brain or left optic radiation can cause a loss of the right field of vision.[3]
Superior hemianopsia – the upper half of the field of vision is affected, possibly because of a tumor beginning to compress the lower part of the chiasma, typically one from the hypophysis.
Inferior hemianopsia – the lower half of the field of vision is affected, possibly because of a tumor beginning to compress the upper part of the chiasma, typically a craniopharyngioma.
Quadrantanopiaedit
Superior right quadrantanopia
Quadrantanopia (quadrantanopsia or quadrantic hemianopsia) is decreased vision or blindness in one quarter of the visual field. The particular quarter of vision missing depends on whether the location of the brain damage is temporal or parietal, and the side of the lesion.[4] For example, a lesion to the right temporal lobe with damage specifically to Meyer's loop will give rise to a left upper (superior) quadrantanopsia, while a lesion to the right parietal radiation with damage specifically to Baum's loop will result in a left lower (inferior) quadrantanopsia.[5]
Visual neglectedit
Visual neglect (also called hemispatial neglect or unilateral spatial neglect) differs from hemianopsia in that it is an attentional deficit rather than a visual one. Unlike patients with hemianopsia who actually don't see, those with visual neglect have no trouble seeing but are impaired in attending to and processing the visual information they receive. Whereas hemianopsia can be assuaged by allowing patients to move their eyes around a visual scene (ensuring that the entire scene makes it into their intact visual field), neglect cannot. Neglect can also apply to auditory or tactile stimuli and can even leave a patient unaware of one side of his or her own body.[6]
Ellis and Young (1998) showed that neglect can also affect patients' mental maps such that if they are asked to picture themselves standing in a familiar location and name the buildings around them, they will neglect to name the buildings on their impaired side but will be able to name them when asked to mentally face the opposite direction.[7]
Some patients with neglect also have hemianopsia, however the two often occur independent of one another.
Surgical interventions have also been shown to ameliorate certain forms of hemianopia due to counterbalancing brain lesions due to a process known as the Sprague effect.[9]
Notesedit
^Hemianopia (Hemianopsia) 16 May 2017 at the Wayback Machine, helpforvisionloss.com
^Gazzaniga, Michael; Ivry, Richard; Mangun, George (2013). Cognitive Neuroscience: The Biology of the Mind (4th ed.). W. W. Norton & Company. pp. 9. ISBN978-0393913484.
^Caramazza, A.; Hillis, A. E. (1990). "Spatial representation of words in the brain implied by studies of a unilateral neglect patient". Nature (Letter). 346 (6281): 267–269. Bibcode:1990Natur.346..267C. doi:10.1038/346267a0. PMID 2374591. S2CID 4349041.
^Ellis, A. W. & Young, A. W. (1988). Human cognitive neuropsychology. Hove, UK: Erlbaum. Visual Extinction and Unilateral Neglect & Denial (pp. 76-79).
^Jiang, Huai; Stein, Barry E.; McHaffie, John G. (29 May 2015). "Multisensory training reverses midbrain lesion-induced changes and ameliorates haemianopia". Nature Communications. 6: 7263. Bibcode:2015NatCo...6.7263J. doi:10.1038/ncomms8263. ISSN 2041-1723. PMC6193257. PMID 26021613.
^Sprague, James M. (23 September 1966). "Interaction of Cortex and Superior Colliculus in Mediation of Visually Guided Behavior in the Cat". Science. 153 (3743): 1544–1547. Bibcode:1966Sci...153.1544S. doi:10.1126/science.153.3743.1544. ISSN 0036-8075. PMID 5917786. S2CID 44648759.
Referencesedit
O'Neill, E., O'Connor, J., Brady, J., Reid, I., and Logan, P. Prism Therapy and Visual Rehabilitation in Homonymous Visual Field Loss. 2011 Optometry and Vision Science, Vol. 88, No 2 February 2011.
Giorgi, RG., Woods, RI., Peli, E. Clinical and Laboratory Evaluation of Peripheral Prism Glasses for hemianopsia. Optometry and Vision Science 2009; 86: 492–502.
External linksedit
Wikimedia Commons has media related to Hemianopsia.
April 10, 2024
hemianopsia, this, article, needs, more, reliable, medical, references, verification, relies, heavily, primary, sources, please, review, contents, article, appropriate, references, unsourced, poorly, sourced, material, challenged, removed, find, sources, news,. This article needs more reliable medical references for verification or relies too heavily on primary sources Please review the contents of the article and add the appropriate references if you can Unsourced or poorly sourced material may be challenged and removed Find sources Hemianopsia news newspapers books scholar JSTOR October 2017 Hemianopsia or hemianopia is a loss of vision or blindness anopsia in half the visual field usually on one side of the vertical midline The most common causes of this damage are stroke brain tumor and trauma 1 HemianopsiaParis as seen with full visual fieldsSpecialtyOphthalmology neurology This article deals only with permanent hemianopsia and not with transitory or temporary hemianopsia as identified by William Wollaston PRS in 1824 2 Temporary hemianopsia can occur in the aura phase of migraine Contents 1 Etymology 2 Types 2 1 Homonymous hemianopsia 2 2 Heteronymous hemianopsia 2 3 Other forms 2 4 Quadrantanopia 3 Visual neglect 4 Management 5 Notes 6 References 7 External linksEtymology editThe word hemianopsia is from Greek origins where hemi means half an means without and opsia means seeing Types editWhen the pathology involves both eyes it is either homonymous or heteronymous Homonymous hemianopsia edit nbsp Paris as seen with left homonymous hemianopsiaA homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes The visual images that we see to the right side travel from both eyes to the left side of the brain while the visual images we see to the left side in each eye travel to the right side of the brain Therefore damage to the right side of the posterior portion of the brain or right optic tract can cause a loss of the left field of view in both eyes Likewise damage to the left posterior brain or left optic radiation can cause a loss of the right field of vision 3 nbsp Paris as seen with binasal hemianopsiaHeteronymous hemianopsia edit nbsp Paris as seen with bitemporal hemianopsiaA heteronymous hemianopsia is the loss of half of the visual field on different sides in both eyes It is separated into two categories Binasal hemianopsia the loss of the fields surrounding the nose Bitemporal hemianopsia the loss of the fields closest to the temples Other forms edit Superior hemianopsia the upper half of the field of vision is affected possibly because of a tumor beginning to compress the lower part of the chiasma typically one from the hypophysis Inferior hemianopsia the lower half of the field of vision is affected possibly because of a tumor beginning to compress the upper part of the chiasma typically a craniopharyngioma Quadrantanopia edit nbsp Superior right quadrantanopiaQuadrantanopia quadrantanopsia or quadrantic hemianopsia is decreased vision or blindness in one quarter of the visual field The particular quarter of vision missing depends on whether the location of the brain damage is temporal or parietal and the side of the lesion 4 For example a lesion to the right temporal lobe with damage specifically to Meyer s loop will give rise to a left upper superior quadrantanopsia while a lesion to the right parietal radiation with damage specifically to Baum s loop will result in a left lower inferior quadrantanopsia 5 Visual neglect editVisual neglect also called hemispatial neglect or unilateral spatial neglect differs from hemianopsia in that it is an attentional deficit rather than a visual one Unlike patients with hemianopsia who actually don t see those with visual neglect have no trouble seeing but are impaired in attending to and processing the visual information they receive Whereas hemianopsia can be assuaged by allowing patients to move their eyes around a visual scene ensuring that the entire scene makes it into their intact visual field neglect cannot Neglect can also apply to auditory or tactile stimuli and can even leave a patient unaware of one side of his or her own body 6 Ellis and Young 1998 showed that neglect can also affect patients mental maps such that if they are asked to picture themselves standing in a familiar location and name the buildings around them they will neglect to name the buildings on their impaired side but will be able to name them when asked to mentally face the opposite direction 7 Some patients with neglect also have hemianopsia however the two often occur independent of one another Management editSome forms of hemianopia can be treated through repeated presentations of multisensory stimuli due to the process of multisensory integration occurring in the superior colliculus 8 Surgical interventions have also been shown to ameliorate certain forms of hemianopia due to counterbalancing brain lesions due to a process known as the Sprague effect 9 Notes edit Hemianopia Hemianopsia Archived 16 May 2017 at the Wayback Machine helpforvisionloss com Gazzaniga Michael Ivry Richard Mangun George 2013 Cognitive Neuroscience The Biology of the Mind 4th ed W W Norton amp Company pp 9 ISBN 978 0393913484 eye human Encyclopaedia Britannica Encyclopaedia Britannica Ultimate Reference Suite Chicago Encyclopaedia Britannica 2010 Definition of term quadranopsia IIDRIS Archived from the original on 30 March 2012 Retrieved 7 April 2021 Toronto Notes 2011 pg N21 Caramazza A Hillis A E 1990 Spatial representation of words in the brain implied by studies of a unilateral neglect patient Nature Letter 346 6281 267 269 Bibcode 1990Natur 346 267C doi 10 1038 346267a0 PMID 2374591 S2CID 4349041 Ellis A W amp Young A W 1988 Human cognitive neuropsychology Hove UK Erlbaum Visual Extinction and Unilateral Neglect amp Denial pp 76 79 Jiang Huai Stein Barry E McHaffie John G 29 May 2015 Multisensory training reverses midbrain lesion induced changes and ameliorates haemianopia Nature Communications 6 7263 Bibcode 2015NatCo 6 7263J doi 10 1038 ncomms8263 ISSN 2041 1723 PMC 6193257 PMID 26021613 Sprague James M 23 September 1966 Interaction of Cortex and Superior Colliculus in Mediation of Visually Guided Behavior in the Cat Science 153 3743 1544 1547 Bibcode 1966Sci 153 1544S doi 10 1126 science 153 3743 1544 ISSN 0036 8075 PMID 5917786 S2CID 44648759 References editO Neill E O Connor J Brady J Reid I and Logan P Prism Therapy and Visual Rehabilitation in Homonymous Visual Field Loss 2011 Optometry and Vision Science Vol 88 No 2 February 2011 Giorgi RG Woods RI Peli E Clinical and Laboratory Evaluation of Peripheral Prism Glasses for hemianopsia Optometry and Vision Science 2009 86 492 502 External links edit nbsp Wikimedia Commons has media related to Hemianopsia Retrieved from https en wikipedia org w index php title Hemianopsia amp oldid 1193011551, wikipedia, wiki, book, books, library,
