Visual fields

Question 1

Visual pathway

Answer 1

Retina
Optic nerve
Optic chiasm: nasal fibres decussate
Optic tract
Lateral geniculate nucleus of thalamus
Optic radiation (superior field: temporal, inferior field: parietal)
Visual cortex

Question 2

investigations for visual field defects

Answer 2

Perimetry

CT/MRI brain

Question 3

Anatomical site of lesion in homonymous hemianopia

Answer 3

Retrochiasmatic
Greater defect = larger lesion or closer to chiasm
Contralateral

Question 4

Extra examinations in homonymous hemianopia

Answer 4

Examine for ipsilateral hemiparesis
Examine for cerebellar signs
Right: test for neglect
Left: test for aphasia

Question 5

Specific history in homonymous hemianopia

Answer 5

Speed of onset

Vascular risk factors

Question 6

Differentiating MCA versus PCA stroke in homonymous hemianopia

Answer 6

MCA stroke:
MCA supplies the optic radiation in the temporal and parietal lobes
Hemiparesis
Higher cortical dysfunction: neglect, aphasia
PCA stroke:
PCA supplies occipital lobe and visual cortex
Homonymous hemianopia with macula sparing (branch of MCA supplies this part of visual cortex)
No hemiparesis
May have cerebellar signs

Question 7

Causes of homonymous hemianopia

Answer 7

Vascular: ischaemia or haemorrhage
SOL: tumour, abscess
Demyelination: MS

Question 8

Lesion site in bitemporal hemianopia

Answer 8

Chiasmatic lesion

Question 9

Specific history in bitemporal hemianopia

Answer 9

Endocrine disease: acromegaly, prolactinoma, Cushing’s

Question 10

Causes of bitemporal hemianopia

Answer 10

Pituitary tumour:
Compresses from below - descending visual loss
Craniopharyngioma:
Compresses from above - ascending visual loss
Benign suprasellar tumour originating from Rathke’s pouch
Calcified as arises out of odontogenic epithelium

Question 11

Monocular blindness lesion site

Answer 11

Lesion proximal to optic chiasm

Optic nerve affected i.e. optic neuropathy