Revision Flashcards
Give an example of a horizontal cell.
Amacrine
What is the function of horizontal cells?
Lateral inhibition - prevent activation of receptors adjacent to the site of highest intensity.
What is amaurosis fugax a sign of?
Ophthalmic or retinal artery occlusion
What imaging can be used to see retinal detachment?
Optical Coherence Tomography
What visual defect would be present if the left inferior optic radiations are damaged?
Right superior quandrantic anoplasia
What visual field defect will be present if the left optic tract is damaged?
Right homonymous hemianopia
What are potential causes of monocular blindness/optic nerve damage?
Children - optic nerve glioma or retinoblastoma
Adults - optic sheath meningioma
What are potential causes of bitemporal hemianopia?
Pituitary tumour
Anterior communicating artery aneurysm
What are potential causes of homonymous hemianopia?
Stroke, neoplasia, trauma
What is Meyer’s loop?
Inferior optic radiations
What is the blood supply to the occipital lobe, what is the significance of this?
Dual blood supply:
PCA
MCA - supplies occipital pole where macula is.
PCA stroke - MCA unaffected -> macula sparing.
What is macula sparing a sign of?
Vascular lesions in occipital lobe
Name the condition caused by MS plaque formation on the medial longitudinal fasciculus.
What sign might you see.
Internuclear ophthalmoplegia
Loss of conjugated eye movements
What visual signs might you see form a tumour of cerebral aqueduct?
CNIII compression - close proximity.
- CN palsy - fixed dilated pupil, ptosis
- Loss of accommodation reflex
How can you differentiate between an optic tract lesion or visual cortex lesion?
Pupillary light reflex - if not functioning then optic tract lesion - no cortical input.
Macula sparing - if present then indicates cortical lesion.
