Exam 4 -- VEP

Question 1

VEP can be used to objectively estimate both a patient’s VA and their contrast sensitivity by taking a series of measurements while changing the stimulus. In order to find the estimated VA or CS, you would then extrapolate from the line created by these measurements to what value?

Answer 1

Zero

Question 2

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would focal PERG show a normal result?

Answer 2

Only hysteria/malingering and amblyopia would show a normal result.

Question 3

With an optic nerve disease such as glaucoma, would a VEP give a normal or abnormal result?

Answer 3

Abnormal (though it may be normal early on in the disease)

Question 4

Kollner’s Rule recap: conditions in the media or in the outer retina cause what type of color vision anomaly? What conditions fall into these categories?

Answer 4

Media/outer retina cause blue-yellow defects.
Media: nuclear sclerosis.
Outer retina: ARMD and diabetic retinopathy

Question 5

What kind of inheritance pattern does Leber’s Congenital Optic Neuropathy exhibit? What kind of visual field defect might a patient with this condition exhibit?

Answer 5

Mitochondrial (mother to child). VF defect might be cecocentral.

Question 6

In amblyopia, would an EOG give a normal or abnormal result?

Answer 6

Normal

Question 7

With hysteria or malingering, would a standard ERG give a normal or abnormal result?

Answer 7

Normal

Question 8

With a macular lesion, would a standard ERG give a normal or abnormal result?

Answer 8

Normal

Question 9

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would standard ERG show a normal result?

Answer 9

All would be normal except retinitis pigmentosa.

Question 10

How could a patient be blind but have a normal VEP?

Answer 10

If the damage causing blindness is located downstream of V1, VEP would be normal (since it focuses between the optic nerve head and V1).

Question 11

In retinitis pigmentosa, would a standard ERG give a normal or abnormal result?

Answer 11

Abnormal

Question 12

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would VEP show a normal result?

Answer 12

Only hysteria/malingering would show a normal result.

Question 13

In amblyopia, would a focal PERG give a normal or abnormal result?

Answer 13

Normal

Question 14

With an optic nerve disease such as glaucoma, would a focal PERG give a normal or abnormal result?

Answer 14

Abnormal

Question 15

In retinitis pigmentosa, would a focal PERG give a normal or abnormal result?

Answer 15

Abnormal

Question 16

On a transient VEP, you expect to see three positive deflections and three positive deflections. Which of the positive deflections is the largest? Which of the negative deflections is the largest?

Answer 16

Positive #2 is the largest; negative #3 is the largest

Question 17

In order to “tease out” a VEP wave from background noise, you have to know when to look for it. This coresponds to the amount of time between the light being flashed to the signal arriving at the striate cortex, which is how long?

Answer 17

80 ms

Question 18

In retinitis pigmentosa, would an EOG give a normal or abnormal result?

Answer 18

Abnormal

Question 19

What changes happen to the VEP of a person with an optic neuropathy, compared to normal? Which optic neuropathy is the one we tend to think about most?

Answer 19

The latency increases. Glaucoma is the optic neuropathy we tend to think about.

Question 20

If you want to know if the fovea is working, which part of the VEP do you care more about: the amplitude or the latency?

Answer 20

Amplitude.

Question 21

In amblyopia, would a standard ERG give a normal or abnormal result?

Answer 21

Normal

Question 22

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would standard ERG show an abnormal result?

Answer 22

Only retinitis pigmentosa would show as abnormal.

Question 23

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would EOG show a normal result?

Answer 23

All would be normal except retinitis pigmentosa.

Question 24

What is the amplitude of the background “brain noise” when you’re doing a VEP?

Answer 24

60 microvolts

Question 25

With an optic nerve disease such as glaucoma, would a standard ERG give a normal or abnormal result?

Answer 25

Normal

Question 26

In retinitis pigmentosa, would a VEP give a normal or abnormal result?

Answer 26

Abnormal (though it may be normal early on in the disease)

Question 27

True or false: in a VEP on a patient with ocular albinism, the amplitude would be decreased and the latency would be decreased.

Answer 27

False; the latency would be normal since the myelination has not been affected. Amplitude would be decreased since the patient has abnormal crossing at the optic chiasm, which decreases their VA (somehow…)

Question 28

With a macular lesion, would an EOG give a normal or abnormal result?

Answer 28

Normal

Question 29

With an optic nerve disease such as glaucoma, would an EOG give a normal or abnormal result?

Answer 29

Normal

Question 30

True or false: VEP overestimates the VA for infants, compared to the values found with forced-preferential looking.

Answer 30

True.

Question 31

With hysteria or malingering, would an EOG give a normal or abnormal result?

Answer 31

Normal

Question 32

With a macular lesion, would a focal PERG give a normal or abnormal result?

Answer 32

Abnormal

Question 33

True or false: concious attention enhances a multifocal VEP.

Answer 33

True.

Question 34

With hysteria or malingering, would a focal PERG give a normal or abnormal result?

Answer 34

Normal

Question 35

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would VEP show an abnormal result?

Answer 35

All would be abnormal except hysteria/malingering. (Note: retinitis pigmentosa and glaucoma may have normal VEP early in the disease)

Question 36

Suppose you did a VEP three times: once stimulating the fovea and the periphery, once stimulating just the fovea, and once stimulating just the periphery. When would the amplitude of the PERG be relatively high, and when would it be relatively low?

Answer 36

The amplitude of a VEP is relative to the amount of fovea stimulated, since a large part of the striate cortex is devoted to foveal vision. So stimulating fovea and periphery would have a high amplitude, but so would stimulating just the fovea. Stimulating just the periphery would have a very low amplitude.

Question 37

What is the amplitude of a typical VEP?

Answer 37

5 microvolts

Question 38

With hysteria or malingering, would a VEP give a normal or abnormal result?

Answer 38

Normal

Question 39

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would focal PERG show an abnormal result?

Answer 39

All would be abnormal except hysteria/malingering and amblyopia.

Question 40

Steady-state VEP is a type of flicker VEP, in that the resulting graph shows a sine wave (in normal patients). What is the most common frequency of the phase-reversing checkerboard pattern used?

Answer 40

20 Hz

Question 41

Suppose you did a pattern ERG three times: once stimulating the fovea and the periphery, once stimulating just the fovea, and once stimulating just the periphery. When would the amplitude of the PERG be relatively high, and when would it be relatively low?

Answer 41

The amplitude of a PERG is relative to the area of the retina stimulated, so the amplitude would be high when stimulating both the fovea and periphery. Stimulating only the fovea but not the periphery (and vice versa) would have a decreased amplitude.

Question 42

Binocular summation in a normal patient would cause an increase in the patient’s VEP when testing binocularly, compared to monocular VEP. By what factor does VEP increase? Patients with what condition will deviate from this pattern?

Answer 42

1.4 (square root of how many eyes we have). Amblyopes will not have an increase of 1.4 in the amplitude of their dominant eye VEP to their binocular VEP.

Question 43

Macular lesion, retinitis pigmentosa, optic nerve disease (such as glaucoma), amblyopia, and hysteria/malingering. For which of these conditions would EOG show an abnormal result?

Answer 43

Only retinitis pigmentosa would show as abnormal.

Question 44

In amblyopia, would a VEP give a normal or abnormal result?

Answer 44

Abnormal

Question 45

With a macular lesion, would a VEP give a normal or abnormal result?

Answer 45

Abnormal

Question 46

True or false: with optic neuritis, VEP latency will increase or decrease as the patient undergoes remissions and exacerbations.

Answer 46

False; once the latency increases, it stays increased.

Question 47

Suppose you are testing a nonverbal patient and would like to know whether the Rx you’ve found improves their VA. You run a VEP without the Rx, then again with the Rx. How do you expect the amplitude of the VEP to change if the Rx does indeed improve VA?

Answer 47

Amplitude should increase (increases with sharper retinal image).

Question 48

Kollner’s Rule recap: conditions in the inner retina and pathways cause what type of color vision anomaly? What conditions fall into these categories?

Answer 48

Inner retina/pathway cause red-green defects.
Inner retina: Leber’s optic atrophy (aka Leber’s Hereditary Optic Neuropathy) and toxic amblyopia (aka toxic optic neuropathy).
Pathway: various lesions