Visual Fields Flashcards by Christie Wong

! Rule out VF defect
! Document VF defect
! Localize pathology in visual pathway ! Monitor disease process over time

Reasons for performing perimetry

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superior 60
inferior 75
temporal 100
nasal 60

normal limits of vf

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!  Corresponds to the optic nerve 
!  15 ̊ temporal to point of fixation
!  1.5 ̊ below horizontal meridian
!  Diameter:
      !  5 ̊ horizontal 
      !  7 ̊ vertical

physiologic blind spot

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VF examination strategies

kinetic perimetry

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! Tests differential light sensitivities of specific retinal locations
on a fixed grid pattern
! Spacing between points varies on type of examination area

static perimetry

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! Grey scale
! Decibel sensitivity plot
! Total deviation numerical & probability plot
! Numerical plot in decibels
! Compares sensitivity at each point to normal population of similar age
! Pattern deviation numerical & probability plot
! Adjusts for generalized depression or elevation of VF

automated static perimetric plots

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! Fixation losses
! False positives
! False negatives

reliability indices

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!  30-2
!  24-2
!  10-2
!  Macular
!  Nasal step: additional 12 locations up to 50 degrees nasal

humphrey vfa

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! Generalized reduction in retinal sensitivity

vf defect depression

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! Focal area of reduced sensitivity surrounded by an area of
normal sensitivity
! Absolute : defect persists when maximum stimulus is used (ie. blind spot)
! Relative: defect present to weaker stimulus, but disappears with brighter stimulus

scotoma vf defect

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where are the axons in the optic nerve

behind the orbit and

near the chiasm

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! Containscrossed(nasal)anduncrossed (temporal) fibers
! Typically situated directly above sella turcica
! Superior: hypothalamus and floor of third ventricle
! Inferior:pituitarygland
! Lateral: IC A and cavernous sinus

chiasmal anatomy

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! Pituitarytumorinvolves

chiasm first

central: directly over sella

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! Pituitarytumorinvolves

chiasm first

prefixed: anterior to sella

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! Pituitary tumor damages optic nerve(s) first

post fixed: posterior to sella

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! Extend from chiasm to LGB
! Fibers from temporal half of ipsilateral eye and nasal half
of contralateral eye
! Visual fields will produce homonymous hemianopia ! Typically incongruous

optic tracts

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!  Relaynucleus
!  Positionedalonglateralaspectof
midbrain
!  Further organization of fibers
!  VF lesions will be hemianopic (congruous or incongruous)

lateral geniculate body

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! SuperiorVF
! MeyersLoop:temporallobe
! Temporal lobe lesions: “pie in thesky”

inferior fibers (optic radiations)

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! InferiorVF
! Loopposteriorlythrough parietal lobe
! Parietallobelesions:“pieonthe floor”

superior fibers

! Medial aspect of occipital lobe ! Significant input from macula
! Central 30 degrees occupy 83% of the striate cortex

visual cortex

blood supply of optic chiasm

circle of willis

blood supply of visual cortex

! Posterior cerebral artery

! Middle cerebral artery

!  Unilateral
!  Invades vertical hemianopic line
!  May respect horizontal line d/t separation of fiber bundles !  Complete/partial vision loss
!  Color vision defect
!  RAPD

lesions of optic nerve clinical findings

!  Optic neuritis
!  Trauma
!  Space occupying lesion (adenoma, glioma, meningioma) !  Ischemic optic atrophy (NAION, AION)
!  Papilledema
!  Nutritional/toxic insult
!  Glaucoma

causes of lesions of optic nerve

``` ! Vision loss ! Typically painless ! Progressive ! Bilateral asymmetric ! Headache possible ! Stretching of diaphragma sella ```

chiasmal disease

``` ! Signs ! +/- VA loss ! VF defect ! Optic atrophy ! APD ! Dyschromatopsia ! +/- endocrine dysfunction ! Diplopia: if adjacent cavernous sinus is involved ```

chiasmal disease signs

``` ! Pituitary adenoma ! Suprasellar meningioma ! ICA aneurysm ! Optic nerve glioma ! Uncommon: ! Trauma ! Inflammation ```

chiasmal disease: etiology

``` ! Causes: compressive disease ! Aka junctional scotoma due to compression of Von Willebrand’s Knee ! Due to post-fixed chiasm ! Clinical findings ! Ipsilateral RAPD ! +/-diplopia ! Ipsilateralcentralscotoma ! Contralateralsuperiortemporaldefec ```

anterior chiasmal syndrome

! Pre-fixed chiasm ! Macular fibers cross posteriorly in chiasm ! Tumor impinges on posterior chiasm and optic tracts ! Clinical findings ! Central bitemporal hemianopic defects (nasal macular fibers) ! Homonymous hemianopia due to optic tract compression

posterior chiasmal syndrome

! Causes ! Suprasellar aneurysm ! Pituitary gland tumors ! Suprasellar meningioma and glioma ! Third ventricular dilation due to obstructive hydrocephalus ! Clinical presentation ! Bitemporal hemianopia ! Bilateral optic atrophy

middle chiasmal syndrome

! Causes ! Distention of 3rd ventricle causing pressure on each side of chiasma ! ICA aneurysm ! Clinical findings ! Binasal hemianopia ! Partial optic atrophy

lateral chiasmal lesions

! Acromegaly: prominent brows/nose/chins ! Cushing Syndrome: moon face, truncal obesity, buffalo hump ! Galactorrhea ! Amenorrhea ! Decreased libido, infertility

endocrine dysfunction

! Band pallor: common ! Diffuse pallor ! APD ! Dyschromatopsia

optic atrophy

! MRI with contrast ! Neurosurgical referral ! Endocrine workup ! Monitor visual fields ! Every 4-6 months until stabilization, then annually

chiasmal disease manaement

! Homonymous: nasal VF of one eye and temporal VF of fellow eye ! Congruous: nasal and temporal defects closely resemble each other ! Fibers posterior to chiasm become more segregated in terms of what part of the VF they represent ! Decreased VA not common unless lesion also involves optic nerve or occipital lobes ! Usually due to cardiovascular disease

post chiasmal disease

``` ! Causes: ! Tumors ! Ischemic stroke ! Aneurysms of superior cerebellar or PCA ! Clinical findings: ! +/- congruous hemianopia ```

optic tract lesions

``` ! Causes: ! Vascular occlusions ! Primary & secondary tumors ! Trauma ! Clinical findings: ! Incomplete incongruous quandranopsias ! Neurologic deficits predominate ```

lesions of optic radiations

``` ! Incongruous “pie in the sky” ! Affects Meyer’s Loop: inferior retinal fibers ! Neurologic symptoms ! Seizures ! Hemiparesis ! Hemisensory loss ! Aphasia ```

temporal lobe lesions

``` ! Incongruous “pie on the floor” ! Affects superior retinal fibers ! Neurologic symptoms ! Hemiplegia ! Hemisensory loss ! Visual neglect ! Aphasia ```

parietal lobe lesion

! Congruous homonymous hemianopia with macular sparing

middle cerebral artery infarct

! Congruous homonymous macular defect

posterior cerebral artery infarct

! Incongruous homonymous hemianopia ! Fibers segregated into R & L side of visual pathway ! Contralateral APD because temporal VF is 40% larger than nasal VF ! Band optic atrophy

optic tracts

! Congruous | ! Very small lesion and very difficult to isolate

LGN post chiasmal vf defects

! Incongruous ! Pie-shaped superior homonymous hemianopia ! Seizures and hallucinations common ! Neurologic symptoms predominate

temporal lobe post chiasmal vf defect

! Congruous, complete or incomplete | ! Neurologic symptoms predominate

parietal lobe post chiasmal vf defect

! Absolute congruity ! Superior and inferior fibers completely separated ! Extreme respect for vertical and horizontal midline ! Homonymous central or macula-sparing defects ! Absence of neurologic symptoms

occipital lobe post chiasmal vf defect