ND - Brain Lesions Causing Visual Field Defects - Week 2 Flashcards
Define homonymous.
Same side
List three possible locations of a lesion if it is chiasmal.
Chiasm
Optic tract
Lateral geniculate nucleus
List three possible locations of a lesion if it is post-chiasmal.
Parietal lobe
Occipital lobe
Other
List the four descriptors that a visual field loss of brain origin needs.
Side (R/L)
Nature (Homonymous/bitemporal/nasal)
Congruity (similarity)
Type of defect - hemianopia/quadrantanopia etc
What are VF defects in the arcuate region called (isolated)? What about if they are joined to BS?
If isolated, Bjerrum scotoma
Otherwise is called arcuate if joined to BS
What can early loss of superficial GCs lead to in terms of ONH appearance?
Gives a steep cup with a notch paracentral to Bjerrum scotoma
What can early loss of deep GCs lead to in terms of ONH appearance?
Gives a honeycomb and saucerised cup appearance
What does a VF defect involve if it respects the horizontal midline?
It involves the RGCs
What do altitudinal VF defects usually indicate for and where?
Ischaemia of one pole of the ONH
Can a banana VF defect be ONH or retina or both?
Could be either
True or false
Defects at or beyond the chaism will affect VF in both eyes.
True
What does a bowtie atrophy indicate the presence of?
A lesion in the contralateral optic tract involving crossed retinal fibres nasal to the fovea.
Are individuals with bitemporal hemianopia symptomatic? Explain.
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
Where is the defect for a pie in the sky VF?
Post-chiasmal - temporal lobe
Where is the defect for a pie on the floor VF?
Post-chiasmal - parietal lobe
