ERG and VEP Lecture sept 20, 2015

1. ERG and VEP for NEURO-VISUAL FUNCTION
ASSESSMENT
J. Alberto Martinez, M.D.

2. CURRENT REALITY
• BY THE TIME WE DIAGNOSE GLAUCOMA, THE
PATIENT HAS HAD IT FOR 5 YEARS! (or more)

3. “In patients who are glaucoma suspects,
PERG signal anticipates an equivalent
loss of OCT signal by several years (as
many as 8 years).”
Invest Ophthalmol Vis Sci. 2013;54:2346–2352)
DOI:10.1167/iovs.12-11026
Per NIH and Bascom-Palmer

4. ASSESSMENT OF NEURO-VISUAL FUNCTION
Neuro-visual Pathway Function Review
1. Anatomy at glance
2. Neuro-physiology at glance
Electrophysiology
1. Visual Evoked Potential (VEP) concepts
2. VEP hardware and software
3. VEP obtaining and interpreting
4. Other electrophysiological tests
Clinical VEP
1. Glaucoma
2. MS
3. Amblyopia
4. Cataract
5. Other
Continued

5. INDEX
VEP and Function Tests
1. VA, CS, CV
2. VF
VEP and Structure Tests
1. HRT, GDx
OCTINDEX
PERG
1. Basics
2. Clinical usage of
PERG
3. Retino-cortical
time.
Q & A
ASSESSMENT OF NEURO-VISUAL FUNCTION

6. Eye
Optic Nerve
Optic Chiasm
Optic Tract
Lateral Geniculate Nucleus
Optic Radiation
Visual Cortex
ANATOMY
ASSESSMENT OF NEURO-VISUAL FUNCTION

7. ANATOMY
Photoreceptor
Bipolar
Ganglion
Ganglion cell axon
Relay neuron
Relay neurons axon
Visual cortex neuron
ASSESSMENT OF NEURO-VISUAL FUNCTION

8. NEURO-PHYSIOLOGY
Phototrans
duction
Conversion of light
into electricity
ASSESSMENT OF NEURO-VISUAL FUNCTION

9. VEP
Photoreceptor
Ganglion cell axon
Relay neuron
Visual cortex neuron
NEURO-PHYSIOLOGY
Bipolar
Light
Phototransduction
Electricity
Electricity
Electricity
Electricity
ASSESSMENT OF NEURO-VISUAL FUNCTION

10. ELECTROPHYSIOLOGY
• Electrocardiogram
• Electromyography
• Auditory Evoked Potential
• Electroencephalogram
ASSESSMENT OF NEURO-VISUAL FUNCTION

11. Electric signal registered at the
occipital region in response to a
visual stimulus.
ASSESSMENT OF NEURO-VISUAL FUNCTION
VEP
Electrical activity of V1 occipital
cortex

12. Electric signal registered at the lower
lid in response to a visual stimulus.
ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG
Electrical activity of retinal ganglion
cells

13. ASSESSMENT OF NEURO-VISUAL FUNCTION
Previous Limitations
• Test time was approximately 45
minutes
• Required highly trained operators
• Limited to large research institutions

15. ASSESSMENT OF NEURO-VISUAL FUNCTION
• Test time is approximately 1
minute
• Does not require highly
trained operators
• Currently installed in about
700 offices worldwide
Current Conditions

16. VEP Stimulus
• Diffuse
• Pattern
Reversal
Pattern-onset
Transient
Steady State
ASSESSMENT OF NEURO-VISUAL FUNCTION

17. • Diffuse Pattern
Reversal
Pattern-onset
Contrast
Color
ASSESSMENT OF NEURO-VISUAL FUNCTION

18. ASSESSMENT OF NEURO-VISUAL FUNCTION
Why would VEP show a functional change on patients with 20/20?
20/20
20/200
20/100
20/50
20/30
20/70
20/100
20/10020/25

19. ASSESSMENT OF NEURO-VISUAL FUNCTION
N75
N135
P100
VEP Components

20. ASSESSMENT OF NEURO-VISUAL FUNCTION
N75
N135
P100
VEP Components
• Amplitude usually
translates to the
number of axons
conducting along the
visual pathway
• Latency usually
translates to the
myelin status of the
visual pathway

21. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

22. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

23. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

24. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

25. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

26. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

27. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

28. Diopsys® VEP Report
ASSESSMENT OF NEURO-VISUAL FUNCTION

29. Main Indications
• Glaucoma
• Multiple Sclerosis
• Ischemic Optic Neuropathy
• Traumatic Brain Injury
• Amblyopia
• Other Neuropathies
ASSESSMENT OF NEURO-VISUAL FUNCTION
VEP

30. VEP and other Ophthalmic Diagnostic Tests
• Psychophysics
• VF
• GDx
• HRT
• OCT
ASSESSMENT OF NEURO-VISUAL FUNCTION

31. Psychophysics of vision
Visual Acuity Test
ASSESSMENT OF NEURO-VISUAL FUNCTION

32. Psychophysics of vision
Contrast Sensitivity Test
ASSESSMENT OF NEURO-VISUAL FUNCTION

33. Psychophysics of vision
Color Vision Test
ASSESSMENT OF NEURO-VISUAL FUNCTION

34. Psychophysics of vision
Visual Field Test
ASSESSMENT OF NEURO-VISUAL FUNCTION

35. ERG mERG pERG mVEP EOG
Electroretinogram
Multifocal Electroretinogram
Pattern Electroretinogram
Multifocal Visual Evoked Potential
Electrooculogram
Electrophysiological tests
ASSESSMENT OF NEURO-VISUAL FUNCTION

36. ASSESSMENT OF NEURO-VISUAL FUNCTION
N35
N95
P50
PERG GENERAL
Concept
Pattern Electroretinography is the electrical signal registered
at the eye because of a pattern stimulation of the retina.

37. ASSESSMENT OF NEURO-VISUAL FUNCTION
Stimulus
(Monitor)
Recording
(Sensors)
Eye stimulation by a
checkerboard pattern
elicits a ganglion cell
response known as PERG.
PERG is an accurate and
objective indicator of
ganglion cell and macular
function.
(ISCEV)
PERG can detect retinal
dysfunction (OHT) before
structural tests.
(Parisi et al.)
pERG

38. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG GENERAL
ERG
PERG
Q

39. 24”
24.1°
Stimulation Monitor
ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG TEST

40. ASSESSMENT OF NEURO-VISUAL FUNCTION
Reproducibility
Factors able to affect the PERG results
• Refraction errors
• IOP
• Diabetes M
• Patient Attention
• Technique
PERG TEST

41. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG TEST
MonofocalMultifocal
PERG should be done with refractive correction for 24”
Uncorrected

42. Diopsys® pERG Electrodes
Comfort Convenience Quality
ASSESSMENT OF NEURO-VISUAL FUNCTION

43. ASSESSMENT OF NEURO-VISUAL FUNCTION
Active for OS
Reference for OD
Active for OD
Reference for OS
Ground
Sensors Position
PERG TEST

44. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG TEST
Active Skin Sensor Placement
Step 1.
Sensor positioning.
Eyelashes
Eyelid Skin

45. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG TEST
Active Skin Sensor Placement
Step 2.
Sensor positioning.
Eyelashes
Eyelid Skin

46. ASSESSMENT OF NEURO-VISUAL FUNCTION
Electrodes Picture Cost ($) Position Amplitude Repeatability Visual Axis
Disturbance
Overall
Discomfort
Usage
DTL 13 Conjunctiva
(invasive)
***** Sensitive to eye
movements
(noise)
** *** Disposable
HK Loop 35 Conjunctiva
(invasive)
***** Sensitive to eye
movements
(noise)
** *** Reusable
Gold Foil 10 Conjunctiva
(invasive)
***** Sensitive to eye
movements
(noise)
** *** Disposable
Gold Cup 13 Skin *** Good ** ** Reusable
Diopsys 11 Skin *** Good * * Disposable
ELECTRODES COMPARISON

47. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG TEST
Q
Protocols
1. VEP TR
2. VEP LX
3. PERG Manual
4. PERG Auto

48. ASSESSMENT OF NEURO-VISUAL FUNCTION
Concentric Fields 24° and 16°
PERG TEST

49. ASSESSMENT OF NEURO-VISUAL FUNCTION
Contrast Sensitivity (higher and lower contrast)
PERG TEST

50. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG
Main Indications
• Glaucoma
• Maculopathies

51. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG CLINIC
Vision problem of unknown cause
VEP
PERG
Differentiating between optic nerve and retinal disorders
Manual
TR

52. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report

53. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report

54. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report

55. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report

56. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report

57. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report
Magnitude DMagnitude D

58. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG Report
Grating Size: 64

59. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG CLINIC
Vision problem of unknown cause
VEP
PERG
Differentiating between optic nerve and retinal disorders

60. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG CLINIC
Normal
Ischemic
Compressive
Toxic
inflammatory
Glaucoma
Nutritional
Hereditary
Q

61. ASSESSMENT OF NEURO-VISUAL FUNCTION
Banitt MR, Ventura LM, Feuer WJ, Savatovsky E, Luna G, Shif O, Bosse B, Porciatti V. Progressive loss of retinal
ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol Vis Sci.
2013;54:2346-52.
IOP Genetic
Oxidative StressNeurotoxicity
Hypoxia

62. ASSESSMENT OF NEURO-VISUAL FUNCTION
Banitt MR, Ventura LM, Feuer WJ, Savatovsky E, Luna G, Shif O, Bosse B, Porciatti V. Progressive loss of retinal
ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol Vis Sci.
2013;54:2346-52.
IOP Genetic
Oxidative StressNeurotoxicity
Hypoxia

63. ASSESSMENT OF NEURO-VISUAL FUNCTION
Banitt MR, Ventura LM, Feuer WJ, Savatovsky E, Luna G, Shif O, Bosse B, Porciatti V. Progressive loss of retinal
ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol Vis Sci.
2013;54:2346-52.
IOP Genetic
Oxidative StressNeurotoxicity
Hypoxia

64. ASSESSMENT OF NEURO-VISUAL FUNCTION
Banitt MR, Ventura LM, Feuer WJ, Savatovsky E, Luna G, Shif O, Bosse B, Porciatti V. Progressive loss of retinal
ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol Vis Sci.
2013;54:2346-52.
IOP Genetic
Oxidative StressNeurotoxicity
Hypoxia

65. ASSESSMENT OF NEURO-VISUAL FUNCTION
Banitt MR, Ventura LM, Feuer WJ, Savatovsky E, Luna G, Shif O, Bosse B, Porciatti V. Progressive loss of retinal
ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol Vis Sci.
2013;54:2346-52.
IOP Genetic
Oxidative StressNeurotoxicity
Hypoxia

76. /Users/jalbertomartinez/Desktop/Suffering
ganglion cells.png

78. ASSESSMENT OF NEURO-VISUAL FUNCTION
Structure Function
Fundus Photograph
(Subjective)
Visual Field
(Subjective)

79. ASSESSMENT OF NEURO-VISUAL FUNCTION
Structure Function
Optical Coherence Tomography
(Objective)
Pattern ERG
(Objective)

80. Healthy
Asymptomatic Symptomatic
VF
Glaucoma
Ellish NJ, Higginbotham EJ. Evaluating a visual field screening test for glaucoma: how the choice of
the gold standard affects the validity of the test. Ophthalmic Epidemiol. 2001 Dec;8(5):297-307.
ASSESSMENT OF NEURO-VISUAL FUNCTION

81. Healthy
Asymptomatic Symptomatic
VF
Glaucoma
OCT
Documented structural damageNon documented structural damage
Schuman JS, Hee MR, Arya AV, Pedut-Kloizman T, Puliafito CA, Fujimoto JG, Swanson EA. Optical
coherence tomography: a new tool for glaucoma diagnosis. Curr Opin Ophthalmol. 1995 Apr;6(2):89-95.
ASSESSMENT OF NEURO-VISUAL FUNCTION

82. Healthy
VF
Glaucoma
OCT
Documented structural damageNon documented structural damage
PERG/VEP
Documented functional damageNon documented functional damage
Parisi V, Miglior S, Manni G, Centofanti M, Bucci MG. Clinical ability of pattern-electroretinograms and
visual evoked potentials in detecting visual dysfunction in ocular hypertension and glaucoma.
Ophthalmology. 2006 Feb;113(2):216-28.
ASSESSMENT OF NEURO-VISUAL FUNCTION
OHT

83. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG CLINIC
Maculopathies

84. ASSESSMENT OF NEURO-VISUAL FUNCTION
pERG CLINIC
Glaucoma Detection

85. ASSESSMENT OF NEURO-VISUAL FUNCTION
pERG CLINIC
Ganglion Cell Function Recovery

86. ASSESSMENT OF NEURO-VISUAL FUNCTION
pERG CLINIC
Macular Function Recovery

87. ASSESSMENT OF NEURO-VISUAL FUNCTION
PERG
PERG provides information about the functionality of the
ganglion cells in the retina.
PERG provides information about reversibility of the
ganglion cells functionality.
PERG provides the earliest information about ganglion cells
dysfunctional.

88. Thanks
Q & A
ASSESSMENT OF NEURO-VISUAL FUNCTION