Visual Fields Flashcards
What is labelled as number 1 on the diagram?
Optic nerve
What is labelled as number 3 on the diagram?
Optic chiasm
What is labelled as number 4 on the diagram?
Optic tract
What is labelled as number 7 on the diagram?
Upper right optic radiations
What is labelled as number 8 on the diagram?
Occipital cortex
What visual field deficit occurs due to a complete lesion of the R optic nerve?
R eye blindness.
Optic nerve severing –> blindness in ipsilateral eye
What visual field deficit occurs due to a lesion of the optic chiasm?
Bitemporal hemianopia
What visual field deficit occurs due to a lesion of the optic tract?
Contralateral homonymous hemianopia
What visual field deficit occurs due to a lesion of the optic radiations?
Contralateral quadrantanopia (e.g. if upper right optic radiations affected then there would be a left superior quadrantonopia)
What visual field deficit occurs due to a lesion of the occipital lobe?
Contralateral homonymous hemianopia
Also cortical blindness and visual agnosia
What visual field deficit occurs due to a lesion of the parietal lobe?
Contralateral inferior homonymous quadrantonopia
What visual field deficit occurs due to a lesion of the temporal lobe?
Contralateral superior homonymous quadrantanopia
What nucleus lies within the optic pathway?
The lateral geniculate nucleus
Which lobe do the superior field of the optic radiations lie in?
Temporal lobe
Which lobe do the inferior field of the optic radiations lie in?
Parietal
How would you want to further investigate a patient with a homonymous hemianopia?
- Examine for ipsilateral hermiparesis
- Examine for cerebellar signs
- If right: Test for neglect
- If left: Test for aphasia
What are the causes of a homonymous hemianopia?
- Vascular: Ischaemic or haemorrhagic
- SOL: Tumour or abscess
- Demyelination: MS
Where is the lesion in a homonymous hemianopia?
Retrochiasmatic contralateral to defect
A greater defect indicates a larger lesion or one closer to the chiasm
What vascular territories affected by a stroke could cause a homonymous hemianopia?
- MCA- middle cerebral artery
- PCA- posterior cerebral artery
What in the visual pathway does the middle cerebral artery supply?
The optic radiations in the temporal and parietal lobes
What symptoms would you expect with an MCA stroke?
- Contralateral homonymous hemianopia
- Hemiparesis
- Higher cortical dysfunction: neglect, aphasia
What does the posterior cerebral artery supply in the visual pathway?
The occipital lobe and visual cortex
What symptoms would you expect with a posterior cerebral artery stroke?
- Homonymous hemianopia with macula sparing (branch of MCA supplies part of visual cortex)
- No hemiparesis
- May have cerebellar signs
What are causes of a bitemporal hemianopia?
- Pituitary tumour
- Compresses from below –> descending visual field loss
- Prolactinoma, Cushing’s, acromegaly
- Craniopharyngioma:
- Compresses from above –> ascending visual field loss
What is a craniopharyngioma?
- Benign suprasellar tumour originating from Rathke’s pouch
- Calcified as arises from odontogenic epithelium
What is monocular vision?
No vision in one eye
Where is the lesion in monocular blindness?
- Proximal to the optic chiasm:
- Eye itself: Cornea, vitreous, retina
- Optic nerve i.e. optic neuropathy
Causes of a right homonymous upper quadrantonopia?
Lesion in left (contralateral) temporal cortex due to:
- CVA (infarct or haemorrhage)
- Intracranial tumour
- Trauma
- Surgery
Causes of a right homonymous lower quantrantanopia?
Lesion in left (contralateral) parietal cortex due to:
- CVA
- Intracranial tumour
- Trauma
