This document discusses visual pathway anatomy and lesions that can occur along the visual pathway. It describes the components of the visual pathway, including the optic nerve, optic chiasm, optic tracts, lateral geniculate bodies, and optic radiations. It details the types of field defects that can result from lesions in each of these areas, such as hemianopia from optic chiasm lesions or quadrantanopia from optic tract lesions. Common causes of lesions are also outlined for each part of the visual pathway. Clinical features of different lesions are compared.

1. Visual Pathway: Lesions

2. VISUAL PATHWAY ANATOMY

3. COMPONENTS OF VISUAL PATHWAY

4. VISUAL
PATHWAY

5. Anopia

6. •Hemianopia: Loss of vision in one half of
visual field
Heteronymous hemianopia

7. Quadrantanopia
Loss of vision in a quadrant of visual field
Homonymous type

8. Homonynous hemianopia
Congruous Incongruous
Defects are
identical in
size,shape,
location, slope
of margins
eg-Post optic
radiation lesions
Defects are
dissimilar
eg-Optic tract &
LGB lesions

9. inverted
reversed

10. LESIONS
OF VISUAL
PATHWAY

11. Field Defects in Lesions of Optic Nerve
Cause:
traumatic avulsion or optic atrophy
Clinical features:
Ipsilateral anopia
(loss of vision)
Loss of direct pupillary reaction
(same side)
loss of consensual pupillary
reaction
(other side)
Near or accommodation reflex is
present

12. Field Defects in Lesions of Optic Chiasma
(Less common)
 IIIrd ventricle
enlargement /
dilatation
 Atheroma of carotids or
posterior
communicating arteries
 Pituitary adenoma
or malignancy
 Craniopharyngioma
 Chronic chiasmal
arachnoiditis
 Fracture of the base
of skull

13. Pituitary Adenoma

14. Craniopharyngioma

15. Field Defects in Lesions of Optic Tract
left optic tract lesion
involving left cerebral
peduncle and left 3rd nerve.

16. Causes of optic tract lesion

17. Field Defects in Lesions of
Lateral geniculate Body (LGB)
sparing of pupillary
reflexes

18. Lesion of optic radiations
Anterior temporal lobe Parietal lobe
Pie in the sky
Pie on the floor
Posterior part of
Internal capsule (Ant
occipital cortex)

19. Common causes of lesions of optic
radiations

20. lesions of optic radiations-Clinical
presentation

21. Field Defects in Lesions of Visual Cortex

22. Common causes of lesions of Visual
Cortex

23. Clinical presentation in Visual Cortex
Lesions (Cortical blindness)
[Anton syndrome]
[Riddoch phenomenon]
[Alexia]

24. Differences between occipital lobe and
optic tract lesions
Clinical Features Occipital lobe
lesion
Optic tract lesion
Pupillary reaction Normal Abnormal
Field defect Congruous Incongruous
Macular involvement Sparing Involved
Optic atrophy
- +

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