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PPMV 2 > Electrophysiology > Flashcards

Electrophysiology Flashcards

1
Q

An ERG has 4 main waves. What are they, are they + or - and what do they indicate

A
  • a wave = negative = photoreceptrs
  • b wave = positive = ON bipolar cells/mueller cells
  • c wave = positive = RPE and rod function
  • d wave = ? = OFF bipolar cells
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2
Q

Oscillatory Potentials (OPs) are indicative of what type of activity in what location?

A

Amacrine cell active in IPL

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3
Q

Where are the 3 electrodes placed for an ERG?

A
  1. Cornea (active)
  2. Earlobe or Forehead (ground)
  3. Forehead or temple (reference)
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4
Q

If a patient has a delay in the B-wave and super-normal response, what disease could it be?

A
  1. Early Siderosis Bulbi
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5
Q

If a patient has a delay in the B-wave with subnormal response, this means what?

A

indicates large area of retina is not functioning

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6
Q

A subnormal b-wave is indicative of what diseases?

A
  1. Early RP
  2. Chloroquine & Quinine Toxicity
  3. Partial RD
  4. Systemic (Vit A def, hyperthyroidism, anemia)
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7
Q

What diseases are associated with complete absence of response?

A
  1. Advanced cases of RP
  2. Complete RD
  3. Leber’s
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8
Q

Abnormalities of the oscillatory potential (OPs) are due to what?

A

Ischemic retinopathy

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9
Q

This type of ERG is only impacted with widespread retinal involvement?

A

Full Field ERG

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10
Q

What type of ERG is best used if patient has poor scotopic threshold on dark adaptation testing?

A

Full Field ERG

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11
Q

This type of ERG is best used to detect damage in a localized area of the retina (central or peripheral).

A

Focal ERG

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12
Q

This type of ERG is best used for macular disease and helps distinguish POOR VA due to macular disease or ON disease.

A

Pattern ERG

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13
Q

What wave on the pattern ERG is the initial corneal positive response and represents macular function?

A

P50 wave

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14
Q

What wave is the immediate corneal negative response and represents ganglion cell function?

A

N95 wave

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15
Q

This ERG looks at the central 40 to 50 degrees of retina; evaluates macula function and areas of concern in central retina.

A

Multi-focal ERG

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16
Q

On a multi-focal ERG, we’ll see small amplitudes in what 2 people?

A
  1. Elderly

2. Highly myopic eye

17
Q

On an EOG, the cornea is ______ and the retina is _____.

A
  • cornea is positive

- retina is negative

18
Q

What is the continuous resting potential of the retina measured by the EOG?

A
  • 6mV
19
Q

For the arden ration, what are the numbers for normal and abnormal? (light peak/dark trough)

A
  • normal = 2.0>

- abnormal = <1.8

20
Q

An EOG is great for diagnosing what disease?

A
  1. Vitteliform Dystrophy (Best’s disease)
21
Q

What is the only test that measures visual cortical activity by determining the integrity of the visual pathway from the retina to visual cortex?

A

VEP: Visual Evoked Potential

22
Q

The VEP reflects activity mainly from what degree of VF?

A

central 10 degrees

23
Q

Where are the 3 electrodes placed for a VEP?

A
  1. Occipital region - active
  2. Top of forehead/earlobe - ground
  3. forehead/top of head - reference
24
Q

Which VEP is used clinically and allows the brain to return to baseline in between flashes

A

Transient VEP - has low temporal frequency

25
Q

Which VEP is used when poor VA, media opacities or poor fixation is present?

A

Flash VEP

26
Q

Which VEP will be abnormal in an amblyopic patient?

A

Pattern VEP

27
Q

What 2 VEPs will be abnormal in an MS patient?

A

Flash and Pattern VEP

28
Q

Which two tests will be abnormal in a macular lesion?

A
  1. Multi-focal ERG

2. Pattern VEP

29
Q

What two tests will be abnormal in a RP patient?

A

EOG and ERG

30
Q

Which is longer: implicit time or latency?

A

Implicit time

31
Q

When separating the waves, which wave is the smallest and occurs first?

A

photopic a wave (ap)

32
Q

We are doing an ERG and light adapt the eye first. What type of response will you see?

A

Cone only response

33
Q

In order to maximize the size of the photopic response of the ERG, what wavelength would you use?

A

550nm

34
Q

When separating the waves, which wave is the largest?

A

Scotopic b wave (bs)

35
Q

Why does the ERG represent mid-peripheral and peripheral retina more than central?

A

Looks at the distribution of PRs throughout the retina

36
Q

The b wave amplitude is larger for who?

A

Women (slightly)

PPMV 2 (15 decks)

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