Central Visual Pathways Flashcards
Describe the pathway of nerves from the eye to the cortex
Optic nerve –> Optic chiasm –> optic tracts –> Lateral geniculate ganglion –> optic radiations –> primary visual cortex
What do the nasal fibres contribute to?
Temporal fields of vision
What do the temporal fibres contribute to
Nasal fields of vision
Which fibres cross in the optic chiasm?
Nasal fibres
How are visual field defects classified?
By which area of vision is lost
What is monocular blindness?
Loss of complete vision in 1 eye
What lesion causes monocular blindness?
Lesion of the optic nerve on the ipsilateral side
Why may monocular blindness occur?
Optic nerve glioma
Retinoblastoma
Trauma
Optic sheath meningioma
What is bitemporal hemianopia?
Loss of temporal fields of vision in both eyes
What is bitemporal hemianopia also known as?
Tunnel vision
Where is the lesion to get bilateral hemianopia?
Optic chiasm affecting both nasal fibres
What may cause a bilateral hemianopia?
Pituitary tumour
Anterior communicating artery aneurysm
What is homonymous hemianopia?
Loss of vision on 1 side of the eye in both eyes
Eg. Temporal in left eye and nasal in right eye- cannot see left portion of vision
What lesion would cause homonymous hemianopia?
Lesion in the optic tract
What causes homonymous hemianopia?
Neoplasia
Stroke
Trauma