Simultaneous ERG and VER in lesions
of the optic pathway
Jerry H. Jacobson, Tatsuo Hirose, and Takashi A. Suzuki
The effects of clinical disease of the retina, optic nerve, chiasm, and cerebrum upon the
electrical activity of the retina (ERG) and the brain, as recorded at the occipital surface
(VER), have been studied and compared to those obtained from the surface of the brain of
cats surgically prepared with similar lesions. In both situations it is possible to detect variations from normal in the responses recorded. The use of the intact opposite eye or hemisphere
as a control is of value in increasing the significance of the findings. A sinusoidally varying
stimulus seems in some instances a more discriminating test of abnormality of function than
a square wave or fiash stimulus.
fecting vision should be facilitated. The
occipital response, however, is technically
more difficult to work with than the ERG
because of its low amplitude, and intrinsically more variable because of such factors as attention and nonvisual stimuli.
This is a report of our experiences with
simultaneous recording of the electrical
activity at the two sites.
.he electroretinogram has proved itself
to be of value as a diagnostic instrument,
especially in those situations in which
subjective testing is not reliable, as for
example, in children. This phenomenon
provides a means of evaluation of the
status of the photopic and scotopic components of the retina as well as of the
total retina.
The visual system, however, consists of
more than merely the retina and, with the
advent of superimposition1 and computer
averaging2 techniques, which have made
recording of the electrical activity of the
brain (VER) evoked by light stimuli feasible,3"5 it has become of interest to determine the clinical applicability of these
techniques.G'23 With objective measurements of occipital and retinal integrity,
determination of the site of a lesion af-
Methods
ERG and VER were recorded with Grass disc
electrodes 8 mm. in diameter placed at the center
of the lower lid, and 2 cm. above and 3 cm.
lateral to the inion, referred to the joined earlobes.
A ground electrode was attached to the chin. Although the ERG observed with a lid electrode is
of lesser amplitude than that obtained with a contact lens electrode, the wave form and the time
relations of the a and b waves are the same as
those with the contact lens,24 and allow location
of the peak of each wave relative to VER components. Precise measurement of the amplitude of
ERG, however, was made separately with the
contact lens. Activity picked up from the left and
right occiput and the lower lid were fed into the
amplifiers of a Grass EEG machine, which had
no filters in the circuit. Time constant was 0.125
seconds, and the characteristics of the amplifiers
are flat from 1 to 1,000 cycles. The output of the
From the Cornell University Medical College,
Department of Surgery (Ophthalmology), New
York, N. Y. 10021.
Supported in whole by Grant No. NB-04987,
National Institutes of Health, United States
Public Health Service, National Institute of
Neurological Diseases and Blindness.
279
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280 Jacobson, Hirose, and Suzuki
EEC machine was led to the computer of average
transients (CAT) and a cathode ray oscilloscope,
after passing through an amplitude equalizing
and reducing circuit. Fifty to 300 responses were
averaged and displayed on the screen. Individual
responses were recorded from a cathode ray oscilloscope.
The photic stimulator is the same as that used
by Nagata and Jacobson.24 Square wave light
stimuli with durations of either 20 to 30 or 100
milliseconds were used at a rate of 3 cycles per
second. There was no audible noise. The light
stimulus was emitted from one end of fiber optics,
6 mm. in diameter, placed 7.5 cm. from the
cornea of the stimulated eye. The light beam
was in line with the visual axis.
Twelve subjects (10 men and 2 women, all
right-handed) between 24 and 42 years of age
served as normal subjects, and 33 subjects with
visual disorders were studied. Pupils were maximally dilated with 10 per cent phenylephrine and
5 per cent tropicamide to avoid possible "habituation" due to change in pupil size.25 The subject
lay supine with one eye open and the other
covered with opaque material. He fixed the open
eye at the center of the stimulus light in a dark,
quiet, electrically shielded room.
Results
7. Normal VER. Two cm. above the
inion at the midline, the VER consisted
of several components. The initial occipital
surface negative wave peak at 46 milliseconds, followed by surface positive, negative, positive, and negative waves, at 68,
115, 155, and 188 milliseconds, respectively (Fig. 1). Although the stimulus
parameters, including duration and intensity, were different from those used by
Ciganek,4 the basic patterns of these responses are similar to his results. These
negative and positive waves were labeled
I, II, III, IV, and V, according to Ciganek's
designation. One additional pair of positive (VI) and negative (VII) waves usually follows the V wave, but these are not
constant as to form and latency. Frequently, a small surface positive wave preceded
wave I. Its peak lay at 18 to 32 milliseconds (Fig. 1, arrow). This may be
similar to the wave which Cobb and
Dawson~(i described as the initial positive
deflection. Rarely, this initial positive wave
was further divided into two humps by
an interposed small surface negative wave
Investigative Ophthalmology
)une 1968
at about 24 milliseconds. The amplitude
of each wave was measured from the peak
or trough immediately preceding. As the
electrode was moved laterally from the
midline, waves I and II tended to decrease
in amplitude. Wave III did not decrease,
and at 3 cm. lateral, it achieved its maximum. Further lateral displacement tended
to decrease its amplitude. Waves IV and V
increased in amplitudes and became maxi-
Fig. 1. Normal VER and ERG recorded simultaneously on cathode ray oscilloscope (A) and
computer of average transients (B). VER recorded
2 cm. above inion at midline, referred to joined
earlobes. Stimulus intensity, 1.3 x 10s foot-lamberts, 3 cycles per second to one eye. Negativity
at occiput presented as upward deflection of recording. A, Ten responses superimposed. B, First
trace: VER; Second trace: ERG from lower lid.
Positivity of lid resulted in upward deflection.
Third trace: stimulus shape and 1 microvolt calibration for first trace and 5 microvolts for second
trace. Two hundred and fifty responses averaged.
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Lesions of the optic pathway 281
Volume 7
Number 3
mal 5 cm. lateral to the midline. A further
lateral position decreased the amplitude.
Along a parasagittal line 3 cm. lateral to
the midline, the responses were largest
between 2 and 4 cm. above the inion.
Anterior or posterior to these the responses
were smaller and their peaks delayed.
To record the VER from patients, we
positioned the electrodes 3 cm. lateral
to 2 cm. above the inion. Fig. 2 demonstrates the combined VER with this electrode position and ERG with several
stimulus intensities of two different durations. The maximum intensity was 2.5 x 10n
-3.0
-2.0
-1.0
-0.5
-0.3
on off
50 msec.
Fig. 2. VER from normal subject with different stimulus intensities and durations. Maximum
stimulus intensity of neutral filters in stimulus path. Left column: 20 milliseconds duration
stimulus. First and second traces, VER from ipsilateral and contralateral occiput (3 cm. lateral
to 2 cm. above inion), respectively. Third trace, ERG. Fourth trace signifies stimulus
shape and calibration of 1 microvolt for VER and 5 microvolts for ERG. Left column: 100
milliseconds' duration stimulus. First trace, VER of contralateral occiput. Second trace, ERG.
Third trace, stimulus shape and calibration 1 microvolt for VER, 5 microvolts for ERG.
Negativity of occiput (VER) and positivity of lower lid (ERG) produce upward deflection.
Two hundred and fifty responses averaged.
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282 Jacobson, Hirose, and Suzuki
foot-lamberts. The figures at left indicate
density of neutral filters placed in the
stimulus path. The topmost trace of each
group is the VER from the ipsilateral
occiput and the second from the occiput
contralateral to the stimulated eye. The
third trace is the ERG, picked up from
the lower lid of the same eye. The lowest
trace is a calibration signal and a record
of time of stimulus. Two hundred and fifty
responses were averaged.
The left column consists of responses
to 20 milliseconds' duration stimuli. As the
stimulus intensity increased, the peak time
of each component decreased. Wave I and
the initial positive wave became apparent
at the intensity of -1.0. Further increase of
the intensity above -0.5 did not produce
increased amplitude of response, but the
II wave was divided into two parts by
the interposition of a negative wave (Fig.
2, -0.3, arrow). This negative wave was
most prominent with 0.0 stimulus. The
right VER was complicated by multiple
humps between peaks of I and III (Fig.
2, 0.0, arrows). The interval of these peaks
was 7.5 to 10 milliseconds, corresponding
to the "on rhythms" reported by Yokoyama,20 who has found a close relation of
on rhythms to the oscillatory potential of
the ERG. Others20'27 have observed similar waves. The amplitudes of the VER
was almost equal in the two hemispheres,
although III and IV waves of the contralateral VER tended to be larger than those
of ipsilateral VER. On rhythms could be
recognized only in the contralateral response under these conditions. These findings agree with those of others.11 Asymmetry of peak time of I to III waves was
not common among normal individuals,
although interindividual differences of VER
were present. The initial positive wave
was observed in 20 per cent; I wave, 60
per cent; II wave, 91 per cent; III and IV
waves, 100 per cent; and V wave, 85 per
cent of normal persons. The peak times
of the initial positive wave, I, II, III, IV,
and V waves were 18 to 38, 45 to 60,
Investigative Ophthalmology
]une 1968
50 to 80, 70 to 120, 125 to 155, and 140
to 200 milliseconds, respectively.
With intense stimulus and stimulus duration of 100 milliseconds (Fig. 2, right
column, 0.0), the VER exhibited rhythmic
humps, regularly spaced, with 30 to 32
milliseconds' peak to peak intervals, starting at 49 milliseconds and persisting until
220 milliseconds after the onset of stimulus.
A small negative hump preceded the first
wave of these rhythmic humps. We have
tentatively called these rhythmic humps
"undulations." The undulations were often
recorded with stimuli of shorter duration
than 100 milliseconds. In Fig. 2, for example, left column, 0.0, the first trace has
this rhythmic tendency. Thus the undulations are not limited to long duration
stimuli. The production of the undulations
may not be ascribed to the change of the
basic pattern of the background EEG. At
the time of recording, the a-wave was
blocked by light, by the fixation of the eye,
and by constant attention to the stimulus
light, and the EEG was typical of an alert
state. With the pattern of EEG unchanged,
less intense stimulation of shorter duration
did not produce undulations. However, we
cannot exclude possible relationship of
these humps to a basic EEG pattern. A
series of rhythmic waves of VER in animal
experiments has shown some relations to
the EEG pattern.2S>29 The undulations we
observed are not the so-called rhythmic
after-discharge,14' 30> 31 since the latter has
a lower frequency similar to the a-wave,
and is usually seen much later after the
stimulus onset than the undulations. The
undulations are not identical with the on
rhythms reported by Yokoyama,20 the latter
being of higher frequency. It is unlikely
that these undulations have the same
physiological significance as I to V waves,
although the peaks of some of the humps
may temporally coincide with those of
I-V waves. The normal human VER components known thus far are: (1) initial
positive wave, I, II, III, IV, V, VI, and
VII waves; (2) rhythmic after-discharge:
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Lesions of the optic pathway 283
Volume 7
Number 3
8 to 12 cycles per second; (3) on rhythms:
100 to 200 cycles per second; and (4) undulations: 31 to 34 cycles per second.
II. Pathology of VER and ERG. In
order to begin to study the effects of disease upon the VER we performed two
types of study. One of these was a study
of the effects of surgically induced lesions
of the optic nerve, the chiasm, and the
optic tract in cats and the second a study
of the effects of human disease processes
verifiable by other techniques.
1. Experimental studies. Fig. 3 demonstrates the result obtained in each of 3
cats studied. In each instance the animal
was immobilized and under local anesthesia. Recordings were from the area of
maximum response in the cortex of normal
cats. If one optic nerve is cut, no occipital
response is evoked by stimulation of that
eye. If the chiasm is cut longitudinally,
no contralateral response was obtained,
while a normal ipsilateral response was
found. Interruption of the optic tract eliminated the response from that hemisphere.
2. Clinical studies. With these experimental findings in mind, patients with
lesions at various sites were studied.
A. RETINAL DISEASE. Patient 1, a 35-yearold man with retinitis pigmentosa, had
had poor night vision for 15 years (Fig. 4,
J. C ) . Fundi revealed normal discs and
retinal vessels of normal caliber. A good
macular ring and foveal reflex was present
in both eyes. Clumps of spidery black
pigment were found about and on the
retinal vessels in the equatorial region.
ERG was nonrecordable with lid or contact lens electrode. VER revealed definite
I to V components of reduced amplitude.
The III wave, in normal subjects the most
prominent component, was especially affected. The peak of each wave lay within
normal temporal range.
Patient 2, a 21-year-old man with retinitis pigmentosa, had been aware of poor
night vision as long as he could remember
(Fig. 5, M. R.). His fundi had waxlike
white-yellow discs with relatively welldefined margins and attenuated vessels.
Unilateral Stim.
Bilateral Stim.
right eye
left eye
R V40 msec
Fig. 3. Cortical responses from surface electrodes on cat cortex at site of maximum response
in normal cat and in animals with surgical lesions at sites indicated,
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284 Jacobson, Hirose, and Suzuki
I
J.C.
Age 35
Investigative Ophthalmology
}une 1968
Male
R. eye stimulated
L eye stimulated
Diagnosis: Retinitis pigmentosa
R 20..
VER
20
VER
j-
L.eye
O.25sec.
Fig. 4. Patient 1. Patient with mild retinitis pigmentosa. Vision is corrected visual acuity. Dark
adaptation curve obtained with Goldmann-Weekers adaptometer after preadaptation of 2,000
lux for 5 minutes. Absolute threshold for light measured 15 degrees above fovea. Top pair
of records with 30 milliseconds', center with 100 milliseconds' stimuli, lowest pair obtained
with all conditions the same but eyes shielded from stimulus, as control.
M.R.
Age 21
Male
I. eye stimulated
Diagnosis: Retinitis pigmentosa
Vision: L 2%Q
R
20
40
VER
Field
CD
VER
Dark adaptation
i : - -I
•L.eye
(-
0.25»ec.
Fig. 5. Patient 2. Findings in severe retinitis pigmentosa.
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R eye stimulated
-j
Volume 7
Number 3
Lesions of the optic pathway 285
Clumps of bone corpuscle-shaped black
pigment were present at the equatorial
circumference. ERG was nonrecordable in
both eyes with lid and contact lens electrode. VER was present but greatly reduced, consisting only of late positive
wave.
Of 6 other cases with retinitis pigmentosa and nonrecordable ERG, 2 had
nonrecordable VER, 2 had no I to III
waves with small IV and V waves, and 2
had reduced amplitude of all waves of
I to V. Those cases which had no VER
M.S.
Age 70
Female
Diagnosis Bilateral occlusion of
central retinal arteries
Vision: L-L.P.
were advanced cases, both showing optic
nerve atrophy.
This variability of VER findings is
in agreement with those reported by
others.0'1Si 3->33
Patient 3 (Fig. 6, M. S.) had occlusion
of the central retinal artery; she had had
acute loss of vision for 10 days in her
left eye and 23 days in her right prior to
examination. She was only able to detect
hand movements in the temporal field of
the right eye. Fundi revealed edema of
both retinas with a cherry red spot at each
L. eye stimulated
R. eye stimulated
L.eye stimulated
R. eye stimulated
VER
R-H.M.
Lesion
VER
Fig. 6. Patient 3.
R.S.
Age45
Male
Diagnosis: Bilateral acute ret.robulbar neuritis
Vision: L- H.M
..R-H.M.
(temporal field)
Lesion (suspected)
VER
VER
Fig. 7. Patient 4.
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Investigative Ophthalmology
June 1968
286 Jacobson, Hirose, and Suzuki
macula. Retinal arteries were extremely
attenuated and discs pale with blurred
margins. No pulsation of the vessels appeared with pressure on the globes. The
ERG with the contact lens electrode
showed a deep a wave with subnormal b
wave in both eyes, but the b wave of the
right was not as much depressed as that
of the left. VER in response to left eye
stimulation revealed very small amplitude
of I, II, and III waves with peak times
much delayed. L-VER to right eye stimulation showed almost normal I to V waves,
while R-VER gave only small I and II
waves with their peak times slightly delayed. The presence of the well-developed
contralateral VER to the right eye stimulation agrees with the subjective evidence of
a remaining relatively intact visual island
on the nasal part of the retina.
B. OPTIC NERVE DISEASE. Patient 4 had
acute retrobulbar neuritis (Fig. 7, R. S.).
The patient had had loss of vision of
short-term onset for 20 days in the right
eye and 19 days in the left eye prior to
examination. Patient's vision had been reduced to no light perception in both eyes
but had recovered to the point of hand
movements in the temporal field of each
eye when seen. His fundi revealed both
discs of normal color, with slightly blurred
B.R.
Age 15
Male
margins. The retinal veins were engorged.
No exudate or hemorrhage was observed.
ERG of each eye was normal. The L-VER
with stimulation of either eye was of extremely low amplitude with normal peak
times. R-VER to the left eye stimulation
had small amplitude of I, II, III, IV, and
V waves with peak times delayed. R-VER
to right eye stimulation had only small
delayed III, IV, and V waves.
Patient 5 had optic nerve atrophy (Fig.
8, B. R.). At the age of 12 the patient
noted failing vision and ataxia. He was
found to have hydrocephalus secondary to
aqueductal stenosis. He was operated upon
(Torkildsen shunt) at 13 years of age, and
developed staphylococcus meningitis secondary to wound infection. This was
treated with antibiotics and ventriculopleural shunt. When seen, the pupillary
response to light was sluggish, the fundi
were tesselated with pale discs and welldefined margins. The macular ring and
foveal reflex were absent, but the retinal
vessels were within normal limits. ERG
was normal in both eyes, VER showed
only a trace of I to V waves from L-occiput
to the left eye stimulation without significant peak time delay. Eleven other cases
of severe optic nerve atrophy or optic
neuritis had similar findings: reduced am-
L. eye stimulated
Diagnosis: Hydrocephalus
Bilateral optic nerve atrophy
Vision: L-C.F.
VER
R-L.P.
Lesion
ERG
VER
off
Fig. 8. Patient 5.
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R.eye stimulated
Volume 7
Number 3
M.S.
Lesions of the optic pathway
Age
46
Female
I . eye stimulated
R.eye stimulated
Diagnosis: Bitemporal hemianopsia
7
Vision
VER
20/200
Lesionfsuspected)
0 25*
Fig. 9. Patient 6.
C.A.
Age 88 Female
Diagnosis: L-Homonymous hemianopsia
Bilateral incipient senile cataract
stimulated
Lesionfsuspected )
L. eye stimulated
R.eye itimulated
VER
O.25sec.
Fig. 10. Patient 7.
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2S7
Investigatioe Ophthalmology
June 1968
288 Jacobson, Hirose, and Suzuki
plitude of VER and normal or delayed
peak times. Reduction of the amplitude
was not always accompanied by prolongation of peak times.
These findings confirm those of others0'
1 1 , 1 2 , 1 5 , 3G
c. CHIASMAL LESION. Patient 6 had bitemporal hemianopsia without macular
sparing (Fig. 9, M. S.). A diagnosis of
acromegaly had been made 18 years before our examination. She received radiation to the pituitary gland with arrest of
progress of symptoms. One year before
the examination the size of her feet and
jaw increased and she underwent yttrium
90 implantation, resulting in bitemporal
hemianopsia with decreased vision. Fundi
revealed pale discs with well-defined margins, and retinal vessels within normal
limits. ERG was normal in both eyes.
There was a small VER on the side ipsilateral to the stimulus, and much-reduced
or absent contralateral VER.
D. GENICULOCALCAKINE
LESIONS.
Patient
7 had homonymous hemianopsia with macular sparing (Fig. 10, C. A.). A few weeks
prior to examination the patient noted not
seeing objects on the left, with no accompanying systemic symptoms. She had had
a stroke previously, resulting in left hemiparesis several months before, and had
hypertension and arteriosclerosis. Fundi
revealed normal discs with early arteriosclerotic changes. ERG was within normal
limits. L-VER were normal. R-VER with
the left eye stimulus revealed larger I
wave than that of L-VER. The descending
branch of I wave was so gradual that it
was difficult to locate the peak of II wave.
R-VER to the right eye stimulation gave
normal I wave and a little smaller II and
III waves. The peak time of II and III of
the R-VER were delayed to such an extent that they coincided temporally with
that of III and IV, respectively, of the
L-VER, giving an impression of reverse
polarity of the response.
Six other cases with homonymous heminopsia with macular sparing (about 3
) 7 degrees with 5/1000 white object)
showed similar findings on the side of the
involved hemisphere: A normal or slightly
higher amplitude and mostly normal but
occasionally delayed peak time of I wave;
normal or below normal to absent response
of II wave with peak time usually delayed;
and small or absent III wave, the peaks
of which were generally delayed. Gross
asymmetry of the left and right VER is
characteristic. These findings are in agreement, generally, with a number of other
reports.s-10' "• 1(!
In some cases of incomplete homonymous lesions the difference in the response
between the presumably diseased hemisphere and the normal is not striking. In
an attempt to refine our techniques, we
utilized as a stimulus a light source varying in intensity in a sinusoidal manner
about a mean value. A considerable volume of experimental work with this type
of stimulus has been carried out by psychologists, and it has several reasons for
being of potential clinical value. The first
of these is that it is a less drastic stimulus
than one which goes on and off in a
square wave manner, since visual perception is dependent upon the rate of change
of the stimulus. There is experimental evidence that the occipital response to a light
stimulus is "saturable,"35 that is, that a
maximum amplitude exists no matter how
bright, or effective, the stimulus may be.
Thus, if one considers a patient with a
lesion of one hemisphere, a stimulus just
adequate to evoke a maximum response
in the normal hemisphere might be expected to evoke a somewhat lesser response in the diseased hemisphere. If, however, a stimulus of efficacy greater than
liminal adequacy is used, it may drive the
intact portion of the diseased hemisphere
to produce a response equal to that of the
normal, maximally responding hemisphere.
Thus, using a less drastic stimulus, such
as a sine wave, may detect a difference
not visualizable by use or a square wave.
This sort of stimulus has other advantages30—it is possible to vary the frequency and the depth of modulation and hence
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Volume 7
Number 3
P.W.
Lesions of the optic pathivay 289
Age 50
Mole
L eye stimulated
R.eye stimulated
Diagnosis: Partial homonymous hemianopsia
Fig. 11. Patient 8. Square wave stimulus of 30 and 100 milliseconds' durations above and
below, respectively.
the stimulus intensity while maintaining
a constant level of adaptation in the retina,
since the stimulus is varying about a mean
level.
An example of the clinical studies which
indicate that this may be a valuable tool
is shown in Patient 8 (Fig. 11). This 50year-old man has a partial homonymous
hemianopsia. With square wave stimulation there is no essential difference in the
response between the two hemispheres.
Fig. 12, however, recorded with a sinusoidally varying stimulus at 20, 40, and
80 per cent modulation depths, indicates
a significant difference between the two
hemispheres, the response in the right
hemisphere being of clearly less amplitude.
E. WIDESPREAD INTRACRANIAL PATHOLOGY.
One month prior to examination Patient 9
(Fig. 13, C. /.) noted sudden onset of unsteadiness of gait, followed by decreasing
vision. Bilateral blindness was observed
3 weeks prior to examination. Hyperreflexia
generalized. Spinal fluid Papanicolaou
suggested neoplasia. Pneumoencephalogram showed dilatation of both ventricles
consistent with cerebral atrophy. He died
2 weeks after our examination. Postmortem
examination revealed primary carcinoma
of right lung with metastatic adenocarcinoma to brain, meninges, and hydrocephalus. Ocular finding at the time of VER
test showed no pupillary reflex to light
and fundi within normal limits. ERG was
normal in both eyes; VER was not detected. Two other similar cases had similar
ERG and VER findings, as have the patients of others.17
Summary and conclusion
1. ERG and VER were recorded simultaneously with a rectangular light stimulus.
The VER of the normal subject with 20
to 30 milliseconds' duration stimuli consisted of an initial surface positive wave
with peak time of 18 to 38 milliseconds
after the onset of stimulus followed by
negative (I), positive (II), negative (III),
positive (IV), and negative (V) waves at
45 to 60, 50 to SO, 70 to 120, 125 to 155,
and 140 to 200 milliseconds, respectively.
With differing stimulus conditions, oscillations having a 7.5 to 10 milliseconds
peak-to-peak interval and other rhythmic
humps of 30 to 31 milliseconds peak-topeak intervals were observed.
2. Of 8 cases of retinitis pigmentosa,
with nonrecordable ERG, 2 had nonrecordable VER, 2 had no I to III with small
IV and V, and 4 cases had reduced, small
amplitude waves 1 to V. Nonrecordable
VER was associated with an atrophy of
the optic nerve.
3. In occlusion of the central retinal
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Investigative Ophthalmology
June 1968
290 Jacobson, Hirose, and Suzuki
20%
40%
80%
Fig. 12. Patient 8. Same patient as Fig. 11, sine wave stimulus at modulation depth indicated. Left column: left eye stimulated. Right column; right eye stimulated. Top trace each
group from left occiput, center from right occiput. Lowest trace of each group 5 microvolts
calibration and stimulus wave form record.
C.J.
Age 52 Male
Diagnosis: Widespread intracranial pathology
Vision:
0 (both)
L.eye stimulated
VER
Lesionfsuspected)
VER
off
Fig. 13. Patient 9.
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\-
O.25sec.
Volume 7
Number 3
artery VER was of reduced amplitude of
I to III, and the peak time was delayed.
4. Patients with optic nerve neuritis and
optic nerve atrophy had reduced amplitude of VER with normal or delayed peak
times and normal or upper normal limit
ERG responses.
5. A patient with bitemporal hemianopsia without macular sparing had little
or no contralateral VER and definite ipsilateral VER with normal ERG.
6. Patients with homonymous hemianopsia with macular sparing showed normal
or slightly increased amplitude of I-wave
with usually normal but occasionally delayed peak time, normal or below normal
amplitude of II with delayed peak time,
and absent or reduced amplitude of III
wave with much delayed peak time in
the involved hemisphere as compared to
the other hemisphere.
7. Widespread intracranial pathology is
associated with nonrecordable or almost
nonrecordable VER from both hemispheres
and normal ERG.
8. Sinusoidal stimulation seems in some
instances to be a more delicate detector
of abnormality in the VER than a square
wave stimulus.
9. Although individual differences do exist between the VER patterns of normal
humans, the major components (II to IV
waves) were present and constant in 85
to 90 per cent of those individuals studied.
Using the record obtained from one hemisphere as a control against that of the
other and the study of the responses elicited by stimulation of one eye as opposed
to the other are of importance in increasing the validity of observed variations from
normal responses.
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