Download Carotid Occlusive Disease: Effect of Complete Occlusion of

Carotid Occlusive Disease:
Effect of Complete Occlusion of Internal Carotid Artery
on Intraocular Pulse/Pressure Relation
and on Ophthalmic Arterial Pressure
MAURICE E. LANGHAM, P H . D . , KARIM F. TO'MEY,
AND THOMAS J. PREZIOSI,
759
M.D.,
M.D.
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SUMMARY The intraocular pressure (IOP), tbe intraocular pulse to pressure (pulse/pressure)
relationship, and the ophthalmic arterial pressure have been measured in 20 patients with either unilateral or
bilateral hemodynamically significant lesions of tbe internal carotid arteries (ICA) as determined from
arteriography. Studies were repeated in 5 of the patients after surgical endarterectomy on the obstructed ICA.
In age matched normal subjects the pulse/pressure relations were symmetrical in pairs of eyes, and the
ophthalmic arterial systolic pressure was 89.0 ± 2.1 mm Hg; this was 66 ± 1% of the brachial arterial systolic
pressure. In 19 of 20 patients with carotid occlusive disease in this study the IOP, pulse amplitudes and the
pulse/pressure relationships differed in pairs of eyes. The ophthalmic arterial systolic pressure on the sides
with 95 to 100% ICA stenosis was 49.9 ± 4.05 mm Hg, which was 33 ± 3% of the brachial arterial systolic
pressure. In the remaining eyes the degree of stenosis of the ipsilateral ICA was 3 6 3 ± 7.9%; the corresponding eyes had an ophthalmic arterial systolic pressure of 70.1 ± 5.18 mm Hg, which was 45 ± 4% of the
brachial arterial systolic pressure. Endarterectomy of the occluded arteries caused a significant increase in the
ophthalmic arterial pressure on the ipsilateral side and a smaller increase in the contralateral eye; these
changes were associated with a statistically significant increase in the intraocular pulse and improvement in the
pulse/pressure relation.
Stroke, Vol 12, No 6, 1981
A NON-INVASIVE clinical procedure for measurements of the intraocular pulse to pressure (pulse/pressure) relationship and of the ciliary arterial pressure
has recently been described by Langham and To'mey.1
The intraocular pulse reflects the intraocular
arteriolar vascular pulse caused by the bolus of blood
that enters the eye with each heartbeat. Manometric
studies in animals and man have shown the intraocular pulse to disappear at pressures equal to the
ophthalmic arterial pressure and have shown that experimentally induced ligation of the common carotid
artery caused corresponding decreases in the 2
pressures.*13 Langham and To'mey used a scleral suction cup to induce increased pressure in the eye and a
pressure sensor resting freely against the cornea to
record the decrease of intraocular pulse as a function
of intraocular pressure. Theoretical and manometric
studies have established that the Langham pneumatic
tonometer used in the procedure measures both the intraocular pressure and the pulsatile nature of the intraocular pressure with high fidelity.4"*
The procedure of Langham and To'mey does not
depend on knowledge of the suction pressure to derive
the intraocular pressure as is the case for the alternate
procedures of suction ophthalmodynamometry7'10
and oculopneumoplethysmography.11-lf The system
also differs from the classical procedure of com-
From the W. K. Kellogg Foundation Laboratories, The Wilmer
Institute, The Johns Hopkins University School of Medicine,
Baltimore, MD 21205 (Dr. Langham). Department of
Ophthalmology, The American University of Beirut, Beirut,
Lebanon (Dr. To'mey), and Department of Neurology, The Johns
Hopkins University School of Medicine, Baltimore, MD 21205 (Dr.
Preziosi).
pression (Baillairt) ophthalmodynamometry1'' M and
suction ophthalmodynamometry in that the pulse/
pressure relation is derived from measurements based
on the pulsation of the ciliary arteries. The classical
technique of ophthalmodynamometry is based on
visual observations of the pulsatile flow in the retinal
arteries.7'14
Changes in the ophthalmic arterial pressure resulting from increasing degrees of stenosis of the internal
carotid artery remain to be defined.18"19 In this study
we have applied the procedure of Langham and
To'mey to measure the intraocular pulse/pressure
relation and the ophthalmic arterial pressure in a
group of patients with either unilateral or bilateral
complete or nearly complete occlusions of the internal carotid arteries, and compared the results to an
age-matched group of normal subjects. Studies were
repeated in 5 patients following surgical endarterectomy and the results assessed in relation to angiographic and clinical findings.
Materials and Methods
Patients ranging in age from 51 to 79 years were
referred from the neurology service of The Johns
Hopkins Hospital for ocular examination. These
patients later had cerebral angiography, and 20
patients shown to have a stenosis of the internal
carotid artery of 95% or more were studied. The
results of arteriography were not known at the time
the pulse/pressure studies on the eye were performed.
The percentage occlusion of the internal carotid artery
was based on measurement of the smallest diameter of
the lumen through the stenosis compared to the diameter of the internal carotid artery free from poststenotic dilatation. Age-matched control subjects were
760
STROKE
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10
RIGHT EYE
6, NOVEMBER-DECEMBER
1981
ocular pressure is recorded digitally on a second
channel and the print out is given directly above the
corresponding pulse.20 The pressure sensors are identical for both instruments. The intraocular pressure
readings from both systems have to be corrected for
curvilinearity of the calibration curve at intraocular
pressures exceeding 50 mm Hg. This calibration table
has been described.1 Standardization of the instruments was made daily as described by the manufacturer. The IOP of the subjects was increased using
a scleral suction cup connected via polyethylene tubing to a motorized driven syringe (The Langham
Pressure Cup System, Digilab Laboratories, Cambridge, Massachusetts). The motorized syringe produced a maximal vacuum of 600 mm Hg and was controlled for increasing and decreasing pressure by a 2
pedal foot control.
70 H
60-
VOL 12, N o
LEFT EYE
FIGURE 1. The influence of increasing IOP on the pulse
amplitude of a normal adult subject. The pulse disappeared
at an IOP of approximately 67 mm Hg in both eyes. The
brachial arterial pressure was 110/70 mm Hg.
randomly chosen volunteers with no history of ocular
or chronic systemic disease.
The intraocular pressure and the intraocular pulse
were recorded with either the Alcon Pneumatonograph (Alcon Laboratories, Fort Worth, Texas) or the
Digilab Oculocerebrovasculometer (OCVM) (Digilab,
Inc., Cambridge, Massachusetts). The former instrument has a single recording channel and the intraocular pressure and the pulse amplitude are read from
the record (see figs. 1, 2). The Digilab OCVM instrument has 2 recording channels; the first channel gives
a continuous amplified recording of the intraocular
pulse which remains centered on the recording chart
as the intraocular pressure is increased; the intra-
Measurement of Ocular Pulse-Pressure Relationship
IOPs were recorded on patients in both the seated
and supine positions prior to application of the scleral
cup. Between 5 and 10 complete pulsations were
recorded, and after taking a first set of readings on
both eyes the readings were repeated. To apply the cup
to the left eye, the patient was asked to look to the
right; the cup was placed temporal to the limbus and a
negative pressure of 50 mm Hg applied. The patient
then observed a fixation light placed at 6 ft. The
tonometer was applied perpendicularly to the apex of
the cornea and a minimum of 5 pulses were recorded.
The recordings were repeated as the IOP was increased using 50 mm Hg increments of negative
pressure until the pulse was almost, or completely suppressed. At each pressure increment the ability of the
patient to see the fixation light with the tested eye was
checked. Once the final recording was made the negative pressure was decreased gradually to zero (during
approximately 5 sec) and the cup was lifted from the
eye. (The negative pressure was never released suddenly because this could induce conjunctival
petechiae.) Finally, a reading of IOP and pulse was
Brachial Pressure 150/90 mm Hg
60-
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E
50-
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30-
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RIGHT EY E
LEF TEYE
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FIGURE 2. The influence of increasing intraocular pressure (IOP) on the pulse amplitude
(PA) of a patient with carotid occlusive disease.
The stenosis of the right and left internal
carotid arteries based on arteriography was
100% and 50%, respectively. The first reading
on each eye represents the IOP and the ocular
pulse of the undisturbed eye. Note that the
pulse in the right eye disappeared at an increased IOP below 40 mm Hg whereas the
pulse in the left eye persisted until an IOP of
about 60 mm Hg. The brachial arterial
pressures were 125/70 mm Hg in the 2 arms.
CAROTID OCCLUSIVE DISEASE/Langham el al.
taken on both eyes. At this time the pulse amplitude
and the pulse rate of the untreated eye were approximately equal to the initial values. In the treated eye
the tonographic effect of the induced increase of IOP
caused the final IOP to be less than its initial value.
The pulse amplitude was defined as the pressure
differences between the lowest and highest peaks of
the ocular pulse waveform and was calculated from a
minimum of 5 complete pulsations. These values and
the corresponding IOPs were used to plot the nonlinear pulse/pressure relation, and a line of best fit
through the individual points was drawn by eye. The
point of intersection of this curve with the abscissa
(IOP) was read as the ophthalmic arterial systolic
pressure. All results are expressed as the arithmetic
mean ± the standard error of the mean. The number
of experiments is shown in parentheses.
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Results
Representative recordings of the intraocular pressure (IOP) and the intraocular pulse in pairs of eyes of
a normal subject in the same age group as the patients
with occlusive disease is shown in fig. 1. The IOP and
pulse in the undisturbed eyes were equal and this close
symmetry persisted as the intraocular pressure was increased stepwise by equal increments of the applied
suction pressure. The pulse/pressure relations in the
group of age matched normal subjects were not significantly different from the results on young adult
subjects.1 In all individual subjects a close symmetry
in the pulse/pressure relations was found in pairs of
eyes, and typical examples are included in figure 3. A
comparison of results on normal subjects below and
above 30 yr of age are summarized in table 1.
Typical recordings of the IOP and pulse with induced increase of IOP in a patient with carotid
occlusive disease is shown in figure 2. On the side with
complete occlusion of the ICA the ocular pulse amplitude decreased rapidly with increased IOP and was
completely suppressed at 40 mm Hg. At this pressure
the patient noted dimming and loss of vision which
returned immediately upon our decreasing the IOP.
On the side with 50% stenosis of the internal carotid
artery, the ocular pulse was present at IOPs of 40 and
50 mm Hg but was extinguished at 60 mm Hg; in this
eye full vision was sustained at IOPs of 40 and 50 mm
Hg. The pulse/pressure relations in 19 of the 20
patients with carotid occlusive disease were asymmetric in pairs of eyes.
Table 2 summarizes the ocular findings compared
to the arterial angiographic findings in the 20 patients
with carotid occlusive disease. Asymmetry in either
the IOP or both IOP and pulse was found in all pairs
of eyes, and in 12 of the 40 eyes the IOPs were abnormally low (10 mm Hg or less). The ophthalmic arterial
pressure (OAP) on the side with 95 to 100% internal
carotid stenosis was 49.9 ± 4.05 (25) mm Hg, and the
corresponding brachial arterial systolic pressure
(BrAP)was 155.5 ± 6.13 (20) mm Hg. In 17 of the 20
patients the ophthalmic arterial pressures were
significantly different in pairs of eyes. In the remain-
761
TABLE 1 Summary of Results on 2 Groups of Normal Subjects. IOP Represents Intraocular Pressure, PA is the Pulse
Amplitude, OAP is the Ophthalmic Arterial Systolic Pressure,
BrAP is the Brachial Arterial Systolic Pressure. Results on
Patients Less1 than 30 Years of Age are Taken from Langham
and To'mey.
Parameter
AgeOOyr
Age>30yr
Mean age
IOP (O.D.)
mm Hg
IOP (05.)
mm Hg
PA. (O£>.)
mm Hg
PA. {OS.)
mm Hg
OAP. (O.D.)
mm Hg
OAP. (O.S.)
mm Hg
BrA.P. (syst)
mm Hg
BrA.P. (diast)
mm Hg
Ratio OAP./
BrA.P.
24.3 ± 1.25 (10)
55.85 ± 355 (13)
16.0 ± 054 (10)
165 ± 0.63 (13)
16.3 ± 056 (10)
17.2 ± 0.61 (13)
2.15 ± 0.15 (10)
22 ± 0.12 (13)
2.15 ± 0.15 (10)
22 ± 0.14 (13)
80S ± 23 (10)
88.4 ± 2& (13)
825 ± 2.6 (10)
89.7 ± 32 (13)
123 ± 8.6 (10)
134 ± 6.6 (13)
77.2 ± 52 (10)
79.4 ± 8.0 (13)
0.67 ±0.01 (20)
0.67 ±0.01 (26)
ing 3 patients the differences in the ophthalmic arterial
pressures in pairs of eyes were 3, 8, and 3 mm Hg, and
in each patient the results of arteriography indicated a
similar degree of stenosis in both internal carotid
arteries. The difference in the ophthalmic pressures in
pairs of eyes for all 20 patients was 24.1 ± 3.03 (20)
mm Hg.
In 25 individual eyes ipsilateral to an ICA stenosis
of 95 to 100% the ratio OAP/BrAP was 0.33 ± 0.03
50
60
70
80
Intraocular Pressure (mmHg)
FIGURE 3. The pulse/pressure relationship in the eyes ofa
patient with carotid occlusive disease (broken line) compared to a typical pulse/pressure relationship in eyes of a
normal subject (continuous line). The open and closed
circles represent the right and left eyes, respectively. In the
patient with arterial occlusive disease, arteriography indicated 90% and 70% stenoses of the right and left internal
carotid arteries, respectively; the brachial arterial pressure
in both arms was 155/100 mm Hg. The brachial blood
pressure of the normal subject was 135/95 mm Hg.
STROKE
762
VOL 12, No
6, NOVEMBER-DECEMBER
1981
TABLE 2 Summary of Measurements on 20 Patients with Unilateral or Bilateral 95 to 100% Occlusions of the
Internal Carotid Arteries. All Pressure Measurements were Made on Patients in the Supine Position. The
Percent Occlusion Refers to the Right and Left Internal Carotid Arteries; these Values are Approximations of the Radiologist's Interpretation of Routine Angiograms. IOP Represents the Intraocular Pressure and
PA Represents the Pulse Amplitude.
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1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
ia
19.
20.
IOP/P.A.
(mm Hg)
Oodiuior
(percent)
OJU>.
(mm Hi)
and
Sex
O.D.
OS.
O.D.
OS.
Rt
Li.
Br.BP.
(mmHg)
72 M
65M
59 M
54F
54F
74 M
53M
53M
73 M
74 F
72 M
68M
60M
51 M
63F
53M
79 M
59 F
67 M
65M
9/03
15/4
13/05
15/3
15/2.4
8/1.4
16/1.0
11/1.0
16/2.0
12/3.0
7/1.7
6/03
13/03
15/2.0
9/03
12/1.0
11/0.6
14/2.2
20/25
20/23
12/03
10/2
12/0.7
17/4
23/1.0
9/13
14/03
14/15
22/3.0
15/22
5/0.6
7/1.0
10/05
13/1.0
11/1.0
15/03
8/05
8/1.0
17/2.0
13/1.0
73
93
54
67
88
45
71
27
30
110
65
55
60
58
25
24
33
73
86
80
41
61
87
70
41
56
49
52
54
81
50
63
33
49
45
39
30
29
56
32
100
75
100
95
95
95
0
95
100
15
35
100
35
90
95
100
95
25
0
0
100
95
45
95
100
85
100
40
50
95
100
95
100
100
70
90
100
100
100
100
180/80
170/75
155/90
135/60
175/80
135/70
128/90
135/80
125/70
150/50
170/75
140/80
125/70
170/110
140/80
195/100
148/90
140/60
170/110
230/105
(23). In the remaining 15 eyes the OAP/BrAP ratio
was 0.45 ± 0.04 (15), and the mean degree of stenosis
in the ipsilateral ICAs was 36.5 ± 7.9 (15) %.
Figure 4 summarizes the relationship between the
percentage stenosis of the ICA determined by
arteriography and the ratio of the OAP/BrAP in the
ipsilateral eye. Figure 4 also includes the results from
the normal subjects. The maximal OAP/BrAP value
for eyes ipsilateral to a 100% occlusion was 0.41, and
in normal eyes the lowest value was 0.56. There was
one pair of eyes and one additional eye corresponding
to arteries with 95% stenosis in which the ratio
OAP/BrAP ranged from 0.50 to 0.54.
Effect of Endarterectomy
Five patients had corrective surgery on the stenotic
ICA, and the effect of the operation on the ratio of
OAP/BrAP in pairs of eyes is summarized in table 3,
and a representative record of the intraocular pulses
prior to and following surgery is shown in figure 5.
Clinical descriptions of 2 of these patients which are
representative of the 5, are as follows:
Patient I. A 63-year-old white female had a past
history of basilar vertebral insufficiency. She complained of weakness in the left upper extremity present
for 2 weeks. The patient had been hospitalized 1 and 3
months previously after experiencing "blackout"
spells lasting 15 and 20 min. With the patient supine,
the intraocular pressures were 9 (O.D.) and 11 (O.S.)
mm Hg and the corresponding pulse amplitudes were
0.8 (O.D.) and 1.0 (O.S.) mm Hg. On increasing the
intraocular pressure the pulse disappeared at 25 mm
Hg in the right eye and at 45 mm Hg in the left eye;
the left and right brachial blood pressures were 140/80
mm Hg. The results indicated a marked arterial stenosis on the right side and a lesser but still severe
TABLE 3 Measurements on the Eyes of Patients with
Carotid Occlusiue Disease Prior to and After Unilateral
Internal Carotid Endarterectomy (I.C. (1)). Time is the
Number of Months Following Endarterectomy to Eye (1). The
Per Cent Occlusion is Based on Arteriography of the
Corresponding Internal Carotid Arteries.
Tirrm
Patient
(Months)
1.
0
5
0
5
0
3
0
2
6
0
2
4
2.
3.
4.
5.
OAP/BrAP
Eye (2)
Eye(l)
0.18
032
0.21
0.46
0.43
058
0.29
059
052
0.18
034
036
032
037
0.40
0.44
028
0.43
0.29
033
036
0.12
0.16
0.24
%Occluson
I.C. (1)
I.C. (2)
95
30
95
40
50
70
70
40
40
100
90
0
100
100
90
100
CAROTID OCCLUSIVE DISEASE/Langham et al.
763
100
80-
o
*M
S
FIGURE 4. The relationship between percentage occlusion of the internal carotid artery
(evaluated from arteriography), and the ratio of
ophthalmic arterial pressure to brachiat systolic
arterial pressure. The filled-in circles are results from the patients with occlusive disease,
and the open circles are results from normal
subjects.
60-
o
Z
40
§
*
20H
I
1
0.10
1
1
I •"- " f "
1
Downloaded from http://stroke.ahajournals.org/ by guest on June 15, 2017
arterial stenosis on the left side. Cerebral angiograms
revealed 95% stenosis of the right ICA at its origin.
The right carotid siphon and ophthalmic artery filled
by retrograde flow. The left carotid arteriogram
showed a 60 to 70% narrowing of the lumen of the
ICA at the bifurcation of the common carotid artery.
Endarterectomy was performed on the right ICA. The
ocular examination was repeated 5 months following
surgery. In the supine position the intraocular
pressures were 16 mm Hg in both eyes and the pulse
amplitudes were 1.5 (O.D.) and 1.7 (O.S.) mm Hg.
With increasing intraocular pressure, the pulse
amplitude disappeared at 64 mm Hg in the right eye
and at 58 mm Hg in the left eye; the brachial blood
pressures were 155/100 mm Hg. Visual fields were
normal in both eyes. The patient improved clinically.
Carotid arteriography made 2 years following surgery
showed a narrowing of 30% in the right ICA. The left
ICA appeared unchanged.
Patient 2. A 53-year-old white male had been in good
health until 3 months before examination when he first
experienced dizziness and unsteadiness during manual
work. This was followed by numbness and weakness in
the left arm. Vision was normal. In the supine posi-
W Ac
2 mm
-r
1 1 1
I" 1
1
L
i rithA/VfilftiU R* \
\h
VV
t i
vwvyvw
i
r
•
T
1 1 1
tion, the intraocular pressures were 11 (O.D.) and 14
(O.S.) mm Hg and the corresponding pulse
amplitudes 1.0 (O.D.) and 1.5 (O.S.) mm Hg. The intraocular pulse disappeared at 27 mm Hg (O.D.) and
at 52 mm Hg (O.S.). The brachial blood pressures
were 135/80 (RA) and 130/85 (LA) mm Hg. The subject noted visual loss at these pressures. These results
indicated a severe arterial stenosis on the right side
and a lesser but significant stenosis of the internal
carotid artery on the left side. Visual fields were normal. Cerebral arteriograms revealed 95% stenosis of
the right ICA and an atherosclerotic plaque in the left
ICA near the origin, causing a 40% stenosis. Right IC
endarterectomy was performed. Ocular examination 5
months after surgery showed the intraocular pressures
to be 16 mm Hg in both eyes; the pulse amplitudes
were 1.0 (O.D.) and 1.2 (O.S.) mm Hg; the brachial
arterial pressures were 140/90 mm Hg. The intraocular pulse disappeared at 64 mm Hg in therighteye
and at 61 mm Hg in the left eye. These results indicate
a significant improvement in the ophthalmic arterial
pressure on the operated side. At this time, cerebral
angiography indicated a 40% stenosis of the right
common carotid artery below the bifurcation. The
LEFT bYt
RIGHT EYE
2 mm
"
t
Ratio O.A.P./Br.A.P.
"
• ,"
0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
I
\f
A/
AA
r\/\
—
V
1A
V I
FIGURE 5. Comparison of intraocular pulse
in the 2 eyes of a patient 2 months before (upper
records) and after right internal carotid endarterectomy (lower records). Arteriography
revealed occlusions of 90% and 100% of the
right and left internal carotid arteries, respectively, prior to surgery. Arteriography 2
months after unilateral surgery revealed occlusion of 0% and 100% in the same arteries
(patient 4, table 3).
764
STROKE
plaque, near the origin of the left ICA, was essentially
unchanged. Left endarterectomy was performed at
this time and the recovery was uneventful.
Discussion
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The normal subjects in this study did not have
arteriography and it may be questioned whether it was
justified to consider this group as having patent
arteries. The symmetry of all the measured
parameters in pairs of eyes, including IOP, pulse
amplitude, pulse/pressure curves, and the ophthalmic
arterial pressures, make it highly probable that these
patients were free of significant carotid occlusive disease.
In the present group of patients, stenosis or complete occlusion of one or both internal carotid arteries
was characterized by a marked decrease of the
ophthalmic arterial pressure as determined by the
Langham pneumatic technique and an abnormally
low value of the ratio OAP/BrAP. In the eyes ipsilateral to either a complete occlusion or to a high
grade stenosis this ratio ranged from 0.12 to 0.41 with
a mean value of 0.25 ± 0.02 (14). The corresponding
ratios in normal subjects ranged from 0.54 to 0.86
with a mean of 0.67 ± 0.01 (46) which is significantly
higher than found in the patients with severe stenosis
(p < 0.001).
A well defined difference of patients with a complete
occlusion or medium grade stenosis of the internal
carotid artery versus normal subjects was also seen in
the form and symmetry of the pulse/pressure relation
and in the symmetry in the IOP in pairs of undisturbed eyes. The ocular pulse/pressure curves in
normal subjects of younger and older age groups were
similar and agreed closely with those found in young
adults in a previous study.1 The normal pulse/pressure
relation has a sigmoid shape in which the initial phase
is characterized by rapid decrease of pulse amplitude
when the IOP is experimentally increased 10 to 15 mm
Hg above its normal mean value; a second rapid
decrease of ocular pulse amplitude to zero occurs
when the IOP approaches within 10 to 15 mm Hg of
the ophthalmic arterial pressure (fig. 3).
In patients with either a complete occlusion or a
high grade stenosis of the internal carotid arteries investigated in this study, the decrease in ophthalmic
arterial pressure resulted in a compression of the
ocular pulse/pressure curve and a loss of the plateau;
thus, the pulse amplitude decreased proportionately
with increased IOP. Marked asymmetry of the shape
of the pulse/pressure curves in pairs of eyes was present in 19 of the 20 patients with carotid occlusive disease. The results on the remaining patient differed
from the other 19 patients. This patient had extracranial vascular disease associated, perhaps, with
fibromuscular hyperplasia in both arteries. She was
obese but had been in good health until she suddenly
developed severe right side headache and a left
hemiparesis. Arteriography revealed a marked
narrowing of both internal carotid arteries 1.5 cm distal to the origin with the common carotid arteries,
VOL. 12, N o
6, NOVEMBER-DECEMBER
1981
with 95 to 100% stenosis in both arteries. There was
reconstitution of both carotid arteries in the region of
the carotid siphon which would explain the normal intraocular pressure, the symmetry of the ocular pulses,
and the normal form and symmetry of the pulse/pressure curves.
To comprehend fully the circulatory information
revealed by the pulse/pressure relation it is pertinent
to consider the anatomic and physiologic parameters
determining the relation. Both the steady state intraocular pressure and the intraocular pressure pulse are
derived from the ciliary arterial circulation which
originates from the ophthalmic artery. This system includes the long and short posterior ciliaries and the
anterior ciliary arteries, which supply nine-tenths of
the total ocular blood flow. The steady state intraocular pressure is itself dependent on formation of
aqueous humor which is proportional to the vascular
perfusion of the ciliary body." The retinal artery also
originates from the ophthalmic artery but it provides
only one-tenth of the total ocular blood flow, and does
not contribute significantly to the intraocular pulse
amplitude.
The results of ocular studies made on patients
before and after unilateral endarterectomy revealed
clinically significant improvement in the ophthalmic
arterial pressure and the pulse/pressure relation in
both the eye on the operated side and to a lesser degree
in the opposite eye. These improvements were consistent with the sustained clinical recovery from the
neural deficit.
Acknowledgment
Dr. To'mey was a postdoctoral fellow supported by the Commonwealth Fund, New York, at the time this investigation was undertaken. Our thanks to Dr. George Allen (Department of Neurological Surgery) of The Johns Hopkins Hospital for patient referrals
and for his continued interest and support of this project.
References
1. Langham ME, To'mey KF: A clinical procedure for the measurements of the ocular pulse/pressure relationship and the
ophthalmic arterial pressure. Exp Eye Res 27: 17—25, 1978
2. Eisenlohr JE, Langham ME: The relationship between pressure
and volume changes in living and dead rabbit eyes. Invest
Ophthalmol 1: 63-67, 1962
3. Eisenlohr JE, Langham ME, Maumenee AE: Manometric
studies of the pressure volume relationship in living and
enucleated eyes of individual human subjects. Br J Ophthalmol
46: 536-48, 1962
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Downloaded from http://stroke.ahajournals.org/ by guest on June 15, 2017
Transient Ischemic Attacks and Strokes with
Recovery Prognosis and Investigation
P. R. D.
HUMPHREY,
D.M., M.R.C.P.,
AND JOHN MARSHALL,
M.D., F.R.C.P.
S U M M A R Y This study analyzes 234 patients who recovered from an initial ischemic episode. The object
was to see if the duration of the first episode influenced the chance of finding a treatable lesion or the chance of
a further episode. The initial episodes varied from less than 5 minutes to longer than 3 weeks. There seemed to
be no fundamental difference between transient ischemic attacks (TIAs) (less than 24 hours) and strokes which
recover. However, 51% of those whose initial episode lasted less than 5 minutes had a subsequent stroke compared to 28% of those with an initial episode of more than 24 hours duration. Thirty percent of the former
group who had angiograms had an operable lesion against 10% in the latter group.
It seems that angiography has sufficiently high yield to be warranted in all patients where tbe initial attack
lasted less than 30 minutes. In those with longer attacks the yield from angiography was much lower and noninvasive techniques should be considered in these patients, where available, prior to consideration for
angiography.
Investigation should be based on the degree of functional recovery and not on the arbitrary time division
which normally divides TIAs and strokes.
Bruits were the most reliable clinical indicators of stenosis. However the presence of intermittent claudication, hypertension and age over 50 were all more common in those with carotid stenosis.
Stroke, Vol 12, No 6, 1981
THERE HAVE BEEN many studies concerned with
the natural history, investigation, and management of
transient ischemic attacks (TIAs). These were comprehensively reviewed by Brust in 1977.1 Transient
ischemic attacks are defined as focal neurological
deficits of vascular origin, rapid in onset, with complete recovery in less than 24 hours.3 While the majority of authors have accepted the definition of a TIA
as lasting up to 24 hours, some have taken a shower
duration. Acheson and Hutchinson,1 for example,
considered TIAs to be any event lasting up to 1 hour
while others have taken periods as short as 30
minutes.4 Not all patients whose signs or symptoms
last longer than 24 hours are left with a permanent
deficit. The Stroke Program at the National Institutes
From the Institute of Neurology, National Hospital for Nervous
Diseases, London WC1N 3BG, England.
of Health, Bethesda, Maryland, recommends that
those who recover within 21 days be considered to
have had reversible ischemic neurological deficits
(RIND).3
The clinical features of TIAs are, by definition,
completely reversible and because of this have not
usually been considered to be associated with any
structural damage. However, there is evidence that
this may not always be the case. For instance, while
the CT scan is usually normal, it is known that infarcts
are sometimes seen after what was believed clinically
to be a TIA.5 Cerebral blood flow studies in TIA may
remain focally abnormal for as long as 90 days after
the last clinical event."
The present study sought to determine the
significance of the duration of the first ischemic disturbance with regard to its cause and the prognosis for
further episodes. The question asked was: Is there any
Carotid occlusive disease: effect of complete occlusion of internal carotid artery on
intraocular pulse/pressure relation and on ophthalmic arterial pressure.
M E Langham, K F To'mey and T J Preziosi
Stroke. 1981;12:759-765
doi: 10.1161/01.STR.12.6.759
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Stroke is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1981 American Heart Association, Inc. All rights reserved.
Print ISSN: 0039-2499. Online ISSN: 1524-4628
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