Visual Pathway: Lesions
VISUAL PATHWAY ANATOMY
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COMPONENTS OF VISUAL PATHWAY
VISUAL
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Anopia?Hemianopia: Loss of vision in one half of
visual field
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Heteronymous hemianopia
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Quadrantanopia
Homonynous hemianopia
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CongruousIncongruous
eg-Optic tract &
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LGB lesions
eg-Post optic
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radiation lesionsinverted
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reversedLESIONS
OF VISUAL
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PATHWAY
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Field Defects in Lesions of Optic Nerve
Cause:
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traumatic avulsion or optic atrophyClinical features:
?Ipsilateral anopia
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(loss of vision)
?Loss of direct pupillary reaction
(same side)
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?loss of consensual pupillary reaction(other side)
?Near or accommodation reflex is
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presentField Defects in Lesions of Optic Chiasma
(Less common)
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? I Ird ventricle
enlargement /
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dilatation? Atheroma of carotids or
posterior
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communicating arteries
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Pituitary Adenoma
Craniopharyngioma
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Field Defects in Lesions of Optic Tract
left optic tract lesion
involving left cerebral
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peduncle and left 3rd nerve.Causes of optic tract lesion
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Field Defects in Lesions of
Lateral geniculate Body (LGB)
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sparing of pupillary
reflexes
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Lesion of optic radiationsPie in the sky
Pie on the floor
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Common causes of lesions of opticradiations
lesions of optic radiations-Clinical
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Field Defects in Lesions of Visual CortexCommon causes of lesions of Visual
Cortex
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Clinical presentation in Visual CortexLesions (Cortical blindness)
[Anton syndrome]
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[Riddoch phenomenon]
[Alexia]
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Differences between occipital lobe andoptic tract lesions
Clinical Features
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Occipital lobe
Optic tract lesion
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lesionPupillary reaction
Normal
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Abnormal
Field defect
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CongruousIncongruous
Macular involvement Sparing
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Involved
Optic atrophy
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