Download MBBS Ophthalmology PPT 8 Visual Pathway Lesions Lecture Notes

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COMPONENTS OF VISUAL PATHWAY

VISUAL

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PATHWAY

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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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Congruous

Incongruous

eg-Optic tract &

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LGB lesions

eg-Post optic

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radiation lesions


inverted

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reversed

LESIONS

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 atrophy

Clinical 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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present

Field 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 radiations

Pie in the sky

Pie on the floor

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Common causes of lesions of optic
radiations

lesions of optic radiations-Clinical

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presentation

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Field Defects in Lesions of Visual Cortex

Common causes of lesions of Visual

Cortex

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Clinical presentation in Visual Cortex

Lesions (Cortical blindness)

[Anton syndrome]

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[Riddoch phenomenon]

[Alexia]

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Differences between occipital lobe and

optic tract lesions

Clinical Features

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Occipital lobe

Optic tract lesion

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lesion

Pupillary reaction

Normal

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Abnormal

Field defect

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Congruous

Incongruous

Macular involvement Sparing

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Involved

Optic atrophy

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