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Perception Block 12 > Visual And Ocular Electrodiagnostics II > Flashcards

Visual And Ocular Electrodiagnostics II Flashcards

1
Q

Do you ever to electrodiagnosis all by itself?

A

No

It’s always just a piece of the puzzle to help in diagnosis or management

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2
Q

Most basic

A

EOG

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3
Q

Full-field electro-retinogram (ffERG)

A

Ganz feld

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4
Q

PERG

A

Grating pattern of lines with pattern reversal, no net luminance change

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5
Q

Difference between the VEP and pERG

A

VEP measures at the visual cortex, pERG measures at the retina

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6
Q

Which tests measure a very big response

A

EOG
ECG
ERG

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7
Q

Which tests use signal averaging to find the target voltage and why

A

Because its so small

  • pERG
  • VEP
  • mfERG
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8
Q

A wave

A

Photoreceptors

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9
Q

B wave

A

Bipolar cells

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10
Q

Why is B wave so large

A

Bipolar cells have small potential, but the mueller cells which are glial absorb all of the electrolytes when they are released from the retina. Most of the B wave is not processing the info, just a depolarization effects

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11
Q

What did we do in the pERG lab

A

30Hz flicker

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12
Q

Wat is the best electrode for ERG?

A

Hansen Burian

-contact lens on the cornea

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13
Q

Basic recording rewuries

A

Proper electrode placemtn
Excellent electrode contact
Signal averaging for all voltage potentials

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14
Q

Magnitude D on pERG

A

Takes into account magnitude and phase variability throughout the waveform recording

  • a recording that us in phase throughout the test will produce a magD value close to that of magnitude
  • a recording that is out of phase through the recording will produce a MagD value significantly less than that of mag
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15
Q

What drug can be monitored with pERG

A

Plaquenil

-plaquenil maculopathy

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16
Q

What field would you expect a plaquenil to show loss in on pERG/

A

24 degrees

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17
Q

Objectively measure the functional responses of the entire visual pathway from the anterior segment of the eye to the visual cortex

A

VEP

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18
Q

What is the VEP measuring

A

How much energy is reaching the visual cortex and how long is it taking there

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19
Q

Visual cortex area 17

A

Most organized visual reception in Cortex

-macular fibers are highly represented magnifying dramatically the visual impact of macular and fovea vision

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20
Q

Cortical magnification

A

The macula is represented in a larger area in the cortical areas vs the rest of the retina
-where VEP picks up

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21
Q

N75-P100-N135 complex in VEP

A 
Time latency is measured in ms 
Amplitude is measures in microvolts 
-N=negative
-P=positive
-time= the time it occurred
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22
Q

Where is VEP recorded

A

Inion

-bump on back of skull

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23
Q

Recording VEP

A
  • recorded at inion
  • signal averaged
  • rewuries visual attention
  • uses constant luminance pattern
  • cortical problems manifest as amplitude reactions and or latency increases
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24
Q

If not refracted properly and the targets are blurred in VEP

A

Low amplitude

Same latency

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25
Q

How does amblyopia look on VEP

A

Notice the decrease in amplitude and the delayed response int he left eye

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26
Q

Multiple sclerosis and VEP

A

Extreme delay in response

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27
Q

Sweep VEP

A

Series of different grating sizes quieckly and rely on fact that you have a young healthy system with an infant

  • infants
  • rewuries visual attentions
  • estimates high spatial frequency cut off
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28
Q

Mf ERG

A
  • presents local luminance shifts (flashes)
  • records responses by separation in time
  • providers focal outer layer ERG
  • requires signal averaging
  • requires best fixation
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29
Q

Where is the highest amplitude of ERG in the mfERG

A

Macula

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30
Q

Chloroquine toxicity

A

Produces central vision loss from an outer retinal thinning causing a characteristic bulls eye maculopathy
-hydroxychloroquine used in arthritis is less toxic but is still monitored regularly

31
Q

Chloroquine toxicity increases when

A

Size of dose and duration of therapy

32
Q

MfERG ring ratios

A

Used for hydroxychloroquine toxicity

  • plot the sensitivities in a honeycomb pattern
  • comparing the central peak to zones in the paracentral to look for a shift in a ratio between those to see if you are losing paracentral sensitivity
33
Q

Stimulus for EOG

A

Adaptation

34
Q

Magnitude for EOG

35
Q

Tissue for EOG

36
Q

Components of EOG

A

Arden ratio

37
Q

Signal average for EOG?

38
Q

FfERG (Flash) stimulus

A

Ganzfeld flash

39
Q

FfERg (Flash) magnitude

40
Q

Tissue for ffERG (flash)

A

Photoreceptor
Bipolar/mueller
Ganglion cell

41
Q

Signal average for ffERG (flash)?

42
Q

Components of ffERG (flash)?

A

A-wave
B-wave
Oscillatory pot

43
Q

FfERG (flicker) stimulus

A

Ganzfeld flash

44
Q

Magnitude of ffERG flicker

45
Q

Tissue for ffERG flicker

46
Q

Components for ffERG flicker

A

Amplitude-phase

47
Q

Signal average for ffERG flicker?

48
Q

PERG stimulus

A

Pattern reversal

49
Q

Magnitude for pERG

50
Q

Tissue for pERG

A

Ganglion cell

51
Q

Components of pERG

A

Amplitude and phase

52
Q

Signal average for pERG?

53
Q

Stimulus for mfERG

A

Multi focal flash pattern

54
Q

Magnitude for mfERG

55
Q

Tissue for mfERG

A

Macular function

56
Q

Components of mfERG

A

Focal macular function

57
Q

Signal average for mfERG?

58
Q

VEP stimulus

A

Pattern reversal

59
Q

Magnitude of VEP

60
Q

Tissue of VEP

A

Visual cortex

61
Q

Components for VEP

A

P-100 Amp/latency

62
Q

Signal average in VEP?

63
Q

MfVEP stimulus

A

Multi focal pattern reversal

64
Q

Mgnirtude of mfvep

65
Q

Tissue for mfVEP

A

Focal visual cortex

66
Q

Components of mfVEP

A

Focal cortical function

67
Q

Signal average for mfVEP?

68
Q

Which of the following is thought to give rise to most of the large positive going potential seen in the B wave of the ff flash ERG?

A

Mueller Cells

69
Q

Your 30 year old healthy patient with long standing acuity of 20/02 and 20/80 has no detectable disease and a normal ffERG but has a mild amplitude reduction and small latency delay in the high spatial frequency VEP (P100), occurring only on the OS potential. The OD VEP is normal. What os your diagnosis?

70
Q

Your patient is on hydroxychloroquine and is being monitored by you. He is 65 years old and has been on it for many years. Which LDX would most likely provide the most useful adjunct with other testing

A

MfERG

Possibly pERG, but not the number one test

71
Q

Which of the following tests rewuries the most precise fixation b the patient?

72
Q

Which of the following conditions is frequently characterized by a nearly extinguished ffERG

A

RP

Non recordable ERGs early on

73
Q

Your 35 year old patient has a long standing acuity loss bilaterally that has been getting worse and which is associated with a just noticeable appearance of granular pigmentation in both macular. She does not complain of night vision problems, there is a vague family history of relative “going blind” at a young age. You suspect cone dystrophy. Which of the following ELDX tests would provide you useful information supporting your diagnosis one way or another?

A

FfERG flicker
Dark adapted ffERG
PERG

All of the above

Perception Block 12 (6 decks)

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