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Neuroscience Week 2 > Visual Field Defects > Flashcards

Visual Field Defects Flashcards

1
Q

visual field

A

area of space perceived by the eye

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2
Q

perimetry

A

-used in the general assessment, diagnosis, prognosis and to monitor progression of opthalmologic and neurologic conditions

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3
Q

basic concepts

A
  • temporal field to 90 all the way over
  • nasal to 60/70
  • top and bottom 60-70
  • 17/18 degrees is optic nerve
  • 10 degrees from macula is most clear vision
  • nasal retina receives temporal vision and vice versa
  • macula/fovea is vertical meridian
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4
Q

binocular visual fields

A
  • 60 overlaps on both sides to make binocular vision
  • extra beyond 60 on each lateral side is monocular
  • temporal crecsent
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5
Q

traquair’s island of vision

A

vertical island with 20/20 vision at the top, where the macula is
-z is sensitivity

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6
Q

visual sensitivity/threshold

A
  • depends on several factors
  • age
  • attention level
  • refractive status
  • pupil size
  • media opacities
  • characteristics of stimulus:
  • size
  • intensity
  • color
  • duration
  • movement
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7
Q

kinetic perimetry

A
  • elephant vs mosquito
  • dimmer and smaller at top of island
  • can see brighter and bigger at bottom of island
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8
Q

static perimetry

A
  • comes from top of island to bottom
  • how computer does it
  • you hit button when you see it
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9
Q

strategies for visual field testing

A
  • confrontation
  • amsler grid
  • tangent screen
  • goldmann perimeter
  • humphrey perimeter (automated)
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10
Q

confrontation visual fields 1

A
  • inexpensive, fast, practive
  • examiner dependent- no standardized way of doing it, as sophisticated as examiner and examinee, many different ways
  • examinee dependent-can be tailored for each pt, may be only test you can do in children, lethargic or inattentive pts
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11
Q

confrontation visual field-general and practical rules

A
  • well lit room
  • examiner at arms length away
  • examiner situated at same level/height as pt
  • pt covers one eye- test Right, cover left first with palm of hand and looks at examiners eye-fixation/attention
  • examiner closes contralateral eye (Right)
  • stimulus is presented half way from examiner/examinee distance
  • use different strategies and keep in mind characteristics of field you are plotting
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12
Q

confrontation visual fields-strategies

A
  • use examiners face (tests central 10-15 degrees, central scotomas, hemianopias)
  • finger counting (psuedo-static, consider temporal>nasal, simultaneous stim)
  • finger moving, hand moving (peripheral, monocular temporal crescent)
  • red object-sensitivity
  • palms side by side at midline- hemianopias
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13
Q

amsler grid

A
  • held at 33 cm
  • tests 10 central degrees of VF
  • pt reports any area missing, blurred, distorted
  • pt can monitor VF at home and report any change
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14
Q

tangent screen

A
  • manual kinetic
  • examiner at 1 meter, can look at examinee to assure good fixation
  • tests central 20 degrees of VF
  • may be used as pseudo static
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15
Q

goldmann

A
  • manual kinetic
  • pt faces bowl, examiner assures fixation from peephole
  • tests entire VF
  • primarily kinetic stimuli, can do static
  • stimulus size, light intensity, isotoper
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16
Q

humphrey

A
  • automated
  • pt faces bowl, fixation is monitored by computer
  • standardized, not examiner dependent
  • begins by plotting blind spot (monitors fixation and reliability)
  • checks for false positives (sound only) and false negatives (stimulates known seeing area)
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17
Q

scotoma

A

-portion of VF thats missing

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18
Q

arcuate

A

arc like shape defect produced by retina nerve fiber bundle damage

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19
Q

altitudinal

A
  • superior or inferior defect that respects horizontal median
  • splits horizontally
20
Q

hemianopia

A
  • nasal or temporal defect that respects the vertical median

- splits vertically

21
Q

quadrantanopia

A

-affects one quarter

22
Q

complete/incomplete

A

-extension of type of defect

23
Q

relative/absolute

A

-to the type of stimuli

24
Q

homonymous

A
  • defect is on the same side of both eyes

- right side of both eyes

25
Q

heteronymous

A
  • defect on different side

- right side of right eye and left side of left eye

26
Q

congruous

A

-defect is similar in both eyes

27
Q

incongruous

A

defect is different in both eyes

28
Q

retina

A
  • axons of ganglion cells converge to form the optic nerve
  • a vertical line that crosses the fovea constitutes the nasal-temporal demarcation
  • the horizontal raphe divides the retina into superior and inferior
  • right next to macula are HOV- straight to optic nerve
29
Q

retina-pattern of field loss

A
  • may also have decreased VA
  • general or focal field deficits
  • focal defects correspond to visual lesions
  • central scotoma from foveal lesion
  • arcuate defect in glaucoma
30
Q

optic nerve patter of field loss

A
  • decrease VA and color vision
  • RAPD in asymmetric process
  • no pathognomonic VF defect, but have:
  • altitudinal defect in NAION (ischemia)
  • central depression
  • central scotoma-hereditary, toxic, nutritional
  • see slides
31
Q

projection of nasal visual fibers

A
  • temporal fibers carrying nasal information don’t cross
  • nasal carrying infratemporal cross above
  • nasal carrying supratemporal cross below and go through wilbrand’s knee- lesion there will get R optic nerve and nose supratemporal
32
Q

projection of the papillomacular bundle

A
  • macular fibers form a chiasm within the chiasm
  • macular fibers that cross the optic chiasm do so in its central and posterior portion
  • 20/20 point crosses to both hemispheres
33
Q

classic field loss in center chiasm lesion

A
  • bitemporal hemianopsia (right of right eye and left of left eye)
  • a little farther behind only does crescents on both sides
34
Q

junctional syndrome

A
  • willibrands knee
  • whole right eye and pie of left
  • just before knee is total right eye
35
Q

lesion right after chiasm R crossing to L

A

nasal half of left eye and 2/3 of right half of right eye
-homonymous
(right eye is less because after crossing over)

36
Q

anterior chiasmal syndrome

A
  • ipsilateral optic neuropathy
  • decrease VA, color vision, RAPD
  • contralateral junction scotoma with normal VA and color
37
Q

body of the optic chiasm

A
  • bitemporal field defect
  • quad, hemi, central, peripheral
  • pituitary adenoma
38
Q

rules of retrochiasmal visual pathway

A
  • beyond optic chiasm, lesions to the visual pathway produce homonymous field defects
  • the more posterior the lesion, the more congruous
39
Q

optic tract

A
  • visual fibers maintain their relative position

- pupillary fibers depart optic tract into midbrain

40
Q

LGN

A
  • retinal ganglion cells synapse
  • fibers rotate 90 degrees medially
  • intricate retinotopic organization, lesions produce variety of defects
  • VF tend to be homonymous and may be incongruous
  • vascular lesions tend to respect these boundaries and cause a sector defect (theory)
41
Q

optic tract pattern of field loss

A
  • beyond chiasm, homonymous
  • optic tract- incongruous
  • hemi, quad, scotomatous, complete/incomplete
  • VA spared
  • contralateral RAPD
  • contralateral hemiparesis
42
Q

optic radiations

A
  • parietal carry inferior and go straight back

- temporal carry superior and go front then back

43
Q

temporal optic radiations: pattern of field loss

A
  • anterior lesion in Meyer’s loop: right homonymous incomplete superior quad- pie in the sky
  • posterior lesion- right homonymous complete superior quad (doesn’t respect horizontal meridian)
44
Q

parietal optic radiations: pattern of field loss

A
  • homonymous inferior visual field defects are characteristic
  • more congruous than temporal lobe lesions
45
Q

occipital lobe and visual cortex

A
  • lesions in general cause homonymous congruous defects
  • posterior lobe lesion (central field) 50% of cortex devoted to the central 10 degrees of field
  • anterior lobe lesion, monocular field loss
  • intermediate lesion between 10 and 60 degrees
  • upper bank lesion causes lower field defect and vice versa
46
Q

calcarine cortex loss

A
  • doesn’t cut out total left field at macula- still remains circular-macular sparing
  • can cause variety of visual field defects- sparing of crescent
  • inferior altitudinal central scotomas, bilateral homonymous hemianopic central scotomas with macular sparing

Neuroscience Week 2 (6 decks)

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