ND - Brain Lesions Causing Visual Field Defects - Week 2

Question 1

Define homonymous.

Answer 1

Same side

Question 2

List three possible locations of a lesion if it is chiasmal.

Answer 2

Chiasm
Optic tract
Lateral geniculate nucleus

Question 3

List three possible locations of a lesion if it is post-chiasmal.

Answer 3

Parietal lobe
Occipital lobe
Other

Question 4

List the four descriptors that a visual field loss of brain origin needs.

Answer 4

Side (R/L)
Nature (Homonymous/bitemporal/nasal)
Congruity (similarity)
Type of defect - hemianopia/quadrantanopia etc

Question 5

What are VF defects in the arcuate region called (isolated)? What about if they are joined to BS?

Answer 5

If isolated, Bjerrum scotoma

Otherwise is called arcuate if joined to BS

Question 6

What can early loss of superficial GCs lead to in terms of ONH appearance?

Answer 6

Gives a steep cup with a notch paracentral to Bjerrum scotoma

Question 7

What can early loss of deep GCs lead to in terms of ONH appearance?

Answer 7

Gives a honeycomb and saucerised cup appearance

Question 8

What does a VF defect involve if it respects the horizontal midline?

Answer 8

It involves the RGCs

Question 9

What do altitudinal VF defects usually indicate for and where?

Answer 9

Ischaemia of one pole of the ONH

Question 10

Can a banana VF defect be ONH or retina or both?

Answer 10

Could be either

Question 11

True or false

Defects at or beyond the chaism will affect VF in both eyes.

Answer 11

True

Question 12

What does a bowtie atrophy indicate the presence of?

Answer 12

A lesion in the contralateral optic tract involving crossed retinal fibres nasal to the fovea.

Question 13

Are individuals with bitemporal hemianopia symptomatic? Explain.

Answer 13

Total chiasmal VF hemi-defect can give a hemi-field slide due to the loss of fusion (such as with hyper/eso/exophoria), and this can manifest habitual heterophoria

Question 14

Where is the defect for a pie in the sky VF?

Answer 14

Post-chiasmal - temporal lobe

Question 15

Where is the defect for a pie on the floor VF?

Answer 15

Post-chiasmal - parietal lobe

Question 16

Define the Riddoch phenomenom. What kind of lesions can it occur in?

Answer 16

Perfecption of movement but loss of form

Can occur in occipital lesion

Question 17

Define cortical blindness. What happens to the artery involved?

Answer 17

Total blindness due to bilateral occipital lobe lesions

It infarcts the basilar artery

Question 18

Do pupils react normally in cortical blindness? What about their ERG/VER responses?

Answer 18

Pupil responses are fine
ERG is fine
VER is abnormal

Question 19

Can individuals with cortical blindness have motion perception?

Answer 19

Yes but residual

Question 20

Do individuals with cortical blindness present with a normal fundus exam?

Answer 20

Yesd

Question 21

Is hallucination possible with cortical blindness? Explain.

Answer 21

Yesd, they may have visual percepts (this is CBS) and deny blindness.
They hallucinate - Anton’s syndrom.

Question 22

Describe the procedure to test for cortical VF loss. What does indicate for? What can happen with chronic cases?

Answer 22

Amsler grid
Indicates for scotoma
Cortical filling occurs with chronic cases

Question 23

What two things is simultaneous confrontation good for and not good for?

Answer 23

Good
Screening and testing large peripheral defects
Sensitivity
Not good
Retinal or optic lesions
Small defects