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Ocular Disease 3 - Midterm > Visual Fields > Flashcards

Visual Fields Flashcards

1
Q

where is our physiological blind spot located?

A

15 degrees temporal and 1.5 degres below horizontal meridian
(diameter = 5 degrees horizontal and 7 degrees vertical)

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2
Q

what is kinetic perimetry?

A

a target moves from non-seeing to seeing space (shows the area they can see)
the isopter connects the points with the same sensitivity

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3
Q

what is static perimetry?

A

tests different light sensitivities of specific retinal locations on a fixed grid
(30-2 has 6 degree spacing and 10-2 has 2 degree spacing)

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4
Q

what is the most critical reliability index?

A

false positives = makes the VF look better than it actually is and you will miss actual defects

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5
Q

what is a depression seen on a VF?

A

a generalized reduction in retinal sensitivity

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6
Q

what is a scotoma?

A

focal area of reduced sensitivity
absolute = there with maximum stimuli
relative = disappears with brighter stimuli

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7
Q

what is the visual pathway?

A

retinal ganglion cells - optic nerve - optic chiasm - optic tracts - LGN - optic radiations - visual cortex

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8
Q

what happens to the optic nerve fibers as they travel posterior to the visual cortex?

A

they become more organized

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9
Q

how is the organization of the fibers different from behind the orbit to near the chiasm?

A

behind the orbit = nasal fibers have more space and the macular fibers are in temporal half
near chiasm = macular fibers move to center and temporal fibers have more space

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10
Q

what is located superior and inferior to the optic chiasm?

A 
superior = hypothalamus and floor of 3rd ventricle
inferior = pituitary gland
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11
Q

what is located laterally to the optic chiasm?

A

ICA and cavernous sinus

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12
Q

what happens when the optic chiasm is located anterior to the sella tursica (pre-fixed)?

A

a tumor will involve the optic tracts first

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13
Q

what happens when the optic chiasm is located posterior to the sella tursica (post-fixed)?

A

a tumor will involve the optic nerves first

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14
Q

what is a Von Willebrand’s Knee?

A

fibers from inferior nasal macula cross into contralateral optic nerve before heading into the optic tract
there is a central defect in the eye with the ON lesion and a superior/temporal defect in the eye with the decussing inferior nasal fibers

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15
Q

what type of VF defect is seen at the LGN?

A

hemianopic (congruous or incongruous) with abruptly sloping borders

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16
Q

will a lesion at the LGN have neurologic defects?

A

yes - they will predominate due to damage of thalamus and/or pyramidal tracts (gross impairment of sensation contralateral to lesion, contralateral hemibody weakness/paralysis)

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17
Q

what causes a temporal lobe (inferior optic radiation) defect?

A

tumor, infarction, epilepsy surgery

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18
Q

what are the symptoms for a temporal lobe defect?

A

visual hallucinations in the affected hemifield, hemiparesis, hemisensory loss and seizures

19
Q

what is the VF defect seen in temporal lobe lesions?

A

pie in the sky = superior quadrantonopia (usually incongruous)

20
Q

what are the symptoms for a parietal lobe defect?

A

visual neglect, problems with sensory integration, tactile discrimination, visual-spatial coordination, aphasia, agnosia, and agraphia

21
Q

what is the VF defect seen in parietal lobe lesions?

A

pie in the floor = inferior quadrantonopia (congruous or incomplete)

22
Q

what causes a visual cortex defect and what will it look like?

A

cause = vascular (stroke) or traumatic

see absolute congruity with macular sparring (due to dual blood supply)

23
Q

what is the blood supply to the visual cortex?

A

posterior cerebral artery and middle cerebral artery

24
Q

what forms the posterior cerebral artery?

A

the right sub-clavian + common carotid artery form the basilar artery

25
Q

what forms the middle cerebral artery?

A

a terminal branch from the internal carotid artery

26
Q

what are the clinical findings of an optic nerve lesion?

A

unilateral, invades vertical line/respects horizontal line, complete or partial VA loss, color vision defect and RAPD

27
Q

what are the patterns of VF loss in an optic nerve lesion?

A

central, central-cecal, arcuate, altitudinal, enlarged blind spot, and diffuse loss

28
Q

what are some causes of an optic nerve lesion?

A

optic neuritis, trauma, space occupying lesion, NAION, AION, papilledema, nutritional/toxic, glaucoma

29
Q

what are the clinical findings of a chiasmal lesion?

A

painless/progressive bilateral VA loss, headache, optic atrophy, RAPD, dyschromatopsia, +/- endocrine dysfunction, diplopia

30
Q

what causes a chiasmal lesion?

A

pituitary adenoma, suprasellar meningioma, ICA aneurysm, optic nerve glioma, trauma/inflammation

31
Q

what causes an anterior chiasmal syndrome?

A

post-fixed chiasm = compressive disease

32
Q

what are the clinical findings for anterior chiasmal syndrome?

A

junctional scotoma (due to Von Willebrands knee), ipsilateral APD, +/- diplopia

33
Q

what causes a posterior chiasmal syndrome?

A

pre-fixed chiasm (macular fibers cross posteriorly in chiasm) = tumor impinges on posterior chiasm and optic tracts

34
Q

what are the clinical findings for posterior chiasmal syndrome?

A

central bitemporal hemianopic defects (nasal macular fibers)

35
Q

what causes a middle chiasmal syndrome?

A

suprasellar aneurysm, pituitary gland tumor, suprasellar meningioma and glioma, 3rd ventricle dilation due to obstructive hydrocephalus

36
Q

what is the VF defect seen in middle chiasmal syndrome?

A

bitemporal heianopia and bitemporal optic atrophy

37
Q

what are some associated findings in chiasmal lesions?

A

APD, dyschromatopsia, pallor (band like or diffuse) and endocrine dysfunction

38
Q

what causes a post-chiasmal disease? what does the VF look like?

A

usually due to cardiovascular disease

homonymous (nasal in one eye and temporal in other eye) and congruous

39
Q

what are some causes for optic tract lesions?

A

tumors, ischemic strokes, aneurysms of superior cerebellar artery or PCA

40
Q

what are some causes for optic radiation lesions?

A

vascular occlusions, primary/secondary tumors, trauma

41
Q

what does a lesion of the middle cerebral artery in the visual cortex look like?

A

congruous homonymous hemianopia with macular sparring

42
Q

what does a lesion of the posterior cerebral artery in the visual cortex look like?

A

congruous homonymous macular defect

43
Q

do lesions in the occipital lobe (visual cortex) have neurologic symptoms?

A

no (only the parietal and temporal lobes)

44
Q

what is the duel vascular supply to the visual cortex?

A

vertebrobasilar system (from posterior cerebral artery) and ICA (from middle cerebral artery)

Ocular Disease 3 - Midterm (7 decks)

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