9 - Opth - Visual fields and Optic nerve Flashcards Preview

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Flashcards in 9 - Opth - Visual fields and Optic nerve Deck (14):
1

describe the visual pathway (pre-chiasm)

light projected onto retina in reversed manner
APs transmitted by retinal rod, cone and ganglion cells
Fibres leave eye at optic disc in optic nerve - to chiasm

2

describe visual pathway (chiasm to occipital cortex)

Nasal retinal fibres decussate and join temporal fibres from other eye -- form each optic tract
(tract = ipsilateral temporal retina + contralateral nasal retina fibres)
These fibres synapse at each lateral geniculate body (except those that control pup reflexes)
Fibres then reach occipital cortex

3

describe the visual pathway once fibres leave the lateral geniculate nuclei - including diff between path of upper and lower fibres

Lateral geniculate nucleus > parietal and temporal lobes > optic radiation > occipital (visual) cortex)

UPPER retinal fibres (lower fields) -- through parietal lobes -- upper occipital cortex

LOWER retinal fibres (upper fields) -- through temporal lobes -- lower occipital cortex

4

Field loss corresponds to lesion on...

OPPOSITE side of brain

5

Pre-chiasmal lesions ...

do not respect vertical midline (mononuclear field loss)

6

Chiasmal/Post-chiasmal lesions ...

always respect the vertical midline (hemi/quadrantanopia)

7

Where is the lesion?
paracentral scotoma

Retinal lesions eg AMD, DR, Glaucoma

8

Where is the lesion?
Mononuclear field loss (whole eye visual loss)

Complete optic nerve lesion

9

Where is the lesion?
Bitemporal hemianopia

Chiasm lesion

10

Where is the lesion?
Homonymous hemianopia

optic tract lesion

11

Where is the lesion?
Right Superior Homonymous quadrantanopia

left temporal lesion

(bc sup vision hits lower retinal fibres which travel through temporal lobe)

12

Where is the lesion?
Right Inferior Homonymous quadrantanopia

left parietal lobe

(bc inf vision hits superior retinal fibres which travel through parietal lobe)

13

Where is the lesion?Homonymous hemianopia with macular sparing

optic radiation or occipital cortex

macular cortex at occipital pole supplied by different blood supply)

14

Where is the lesion?
Homonymous hemianopia - hemiscotoma (half macula vision gone)

occipital pole (macular cortex) lesion

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