Transcript Extraocular Motility

Extraocular Motility
Walter Huang, OD
Yuanpei University
Department of Optometry
Extraocular Muscles
Purpose
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To control the movement of the globe
Extraocular Muscles
Rectus muscles
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Superior rectus muscle
(SR)
Inferior rectus muscle (IR)
Medial rectus muscle (MR)
Lateral rectus muscle (LR)
Oblique muscles
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Superior oblique muscle
(SO)
Inferior oblique muscle (IO)
Anterior View of Right Eye
Superior View of Right Orbit
Action of muscles affected by globe
position in the ocular orbit and muscle
orientations
Posterior View of Right Eye
Medial Rectus
Along the medial aspect of the eyeball, the
medial rectus muscle inserts at a point
5.5mm of the limbus
It is controlled by the oculomotor nerve
(cranial nerve III)
Contraction of this muscle causes
adduction of the eye
Medial Rectus
Adduction
Lateral Rectus
Along the lateral aspect of the eyeball, the
lateral rectus muscle inserts at a point
7.0mm of the limbus
It is controlled by the abducens nerve
(cranial nerve VI)
Contraction of this muscle causes
abduction of the eye
Lateral Rectus
Abduction
Inferior Rectus
Along the inferior aspect of the eyeball, the
inferior rectus muscle inserts at a point
6.5mm of the limbus
It is controlled by the oculomotor nerve
(cranial nerve III)
Inferior Rectus
When the eyeball is positioned 23 degrees
outward in the orbit with respect to primary
gaze, contraction of this muscle causes
depression of the eye
When the eyeball is positioned 67 degrees
inward in the orbit with respect to primary
gaze, contraction of this muscle causes
excycloduction of the eye
Inferior Rectus
When the eyeball is positioned straight
ahead in the orbit with respect to primary
gaze, contraction of this muscle causes
adduction of the eye
Contraction of this muscle causes
depression, excycloduction, and adduction
of the eye
Position of IR and SR
Primary Action of IR
Depression
Secondary Action of IR
Excycloduction
Tertiary Action of IR
Adduction
Superior Rectus
Along the superior aspect of the eyeball,
the superior rectus muscle inserts at a
point 7.5mm of the limbus
It is controlled by the oculomotor nerve
(cranial nerve III)
Superior Rectus
When the eyeball is positioned 23 degrees
outward in the orbit with respect to primary
gaze, contraction of this muscle causes
elevation of the eye
When the eyeball is positioned 67 degrees
inward in the orbit with respect to primary
gaze, contraction of this muscle causes
incycloduction of the eye
Superior Rectus
When the eyeball is positioned straight
ahead in the orbit with respect to the
primary gaze, contraction of this muscle
causes adduction of the eye
Contraction of this muscle causes
elevation, incycloduction, and adduction of
the eye
Primary Action of SR
Elevation
Secondary Action of SR
Incycloduction
Tertiary Action of SR
Adduction
Superior Oblique
The superior oblique muscle passes
through the trochlea and its insertion on
the eyeball below the superior rectus
muscle is at 51 degrees with respect to
primary gaze
It is controlled by the trochlear nerve
(cranial nerve IV)
Superior Oblique
When the eyeball is positioned 39 degrees
outward in the orbit with respect to primary
gaze, contraction of this muscle causes
incycloduction of the eye
When the eyeball is positioned 51 degrees
inward in the orbit with respect to primary
gaze, contraction of this muscle causes
depression of the eye
Superior Oblique
When the eyeball is positioned straight
ahead in the orbit with respect to the
primary gaze, contraction of this muscle
causes abduction
Contraction of this muscle causes
incycloduction, depression, and abduction
of the eye
Position of SO and IO
Primary Action of SO
Incycloduction
Secondary Action of SO
Depression
Tertiary Action of SO
Abduction
Inferior Oblique
The insertion of the inferior oblique muscle
is on the eyeball below the lateral rectus
muscle at 51 degrees with respect to
primary gaze
It is controlled by the oculomotor nerve
(cranial nerve III)
Inferior Oblique
When the eyeball is positioned 39 degrees
outward in the orbit with respect to primary
gaze, contraction of this muscle causes
excycloduction of the eye
When the eyeball is positioned 51 degrees
inward in the orbit with respect to primary
gaze, contraction of this muscle causes
elevation of the eye
Inferior Oblique
When the eyeball is positioned straight
ahead in the orbit with respect to the
primary gaze, contraction of this muscle
causes abduction
Contraction of this muscle causes
excycloduction, elevation, and abduction
of the eye
Primary Action of IO
Excycloduction
Secondary Action of IO
Elevation
Tertiary Action of IO
Abduction
Functions of Extraocular Muscles
Muscle
MR
Primary
Action
Adduction
LR
Abduction
IR
Depression
Secondary
Action
Tertiary
Action
Excyclo
duction
Adduction
Functions of Extraocular Muscles
Muscle
Primary
Action
Secondary
Action
Tertiary
Action
SR
Elevation
Incyclo
duction
Adduction
SO
Incyclo
duction
Depression
Abduction
IO
Excyclo
duction
Elevation
Abduction
Terminology
Duction: describes movement of one eye
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Abduction
Adduction
Supraduction or elevation
Infraduction or depression
Incycloduction or intorsion
Excycloduction or extorsion
Terminology
Version: describes movement of two eyes
in the same direction
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Dextroversion
Levoversion
Supraversion
Infraversion
Terminology
Vergence: describes movement of two
eyes in opposite directions
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Convergence
Divergence
Version and Vergence
Near Point of Convergence
Maximum convergence ability or NPC is
measured by as part of confrontational
testing
NPC = point of intersection of line of sight
when eyes are maximally converged
Theoretically, NPC should be measured
from center of rotation of eyes
Clinically, NPC is measured from the facial
plane
Near Point of Convergence
NPC break point (target becomes double)
greater than 7cm is considered abnormal
Average NPC is approximately 5cm
The recovery point (target becomes single)
is expected to be within 10cm
Near Point of Convergence
A patient with reduced NPC
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Convergence insufficiency
Some presbyopes
Symptoms
Diplopia, frontal headache, asthenopia, fatigue,
and reduced reading ability
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The patient may benefit from vision therapy or
prism in reading Rx
Object Tracking Movements
Saccade: fast, step-like eye movement (up
to 1000 deg/sec) that places image of the
target on the fovea
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Reading
Looking from point A to B
Fixating on a stationary target
Object Tracking Movements
Pursuit: slow, smooth-following movement
(up to 30 deg/sec) that maintains image of
the target on the fovea
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Following a moving target
Extraocular Motility Testing
The most common test for extraocular
motility is the broad H test
EOM testing is also part of confrontational
testing
Extraocular Motility Testing
Purpose
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To investigate the integrity of the extraocular
muscles and their nerves
To assess the patient’s ability to perform
version eye movements
To determine if strabismus is comitant (i.e.,
deviation does not change with direction of
gaze)
Broad H Test
A pursuit test done binocularly with
penlight at a test distance of 30 to 40cm
It tests 9 positions of action, starting with
primary position
Broad H Test
Broad H Test
It tests fields of action of the 6 extraocular
muscles
Field of action = direction where a
particular muscle has the greatest action
Broad H Test
Examples of fields of action
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Right LR: field of action is the right-hand field
Right MR: field of action is the left-hand field
This is opposite for left LR and left MR
Position of SR and IR
Action of SR and IR
SR and IR lie in a muscle plane that
makes a 23 degree angle with the straight
ahead position
When the eye turns out 23 degrees, SR
acts as a pure elevator, and IR acts as a
pure depressor
Position of SO and IO
Action of SO and IO
SO and IO lie in a muscle plane that
makes a 51 degree angle with the straight
ahead direction
When the eye turns in 51 degrees, SO
acts as a pure depressor, and IO acts as a
pure elevator
Broad H Test
It is not necessary to direct the patient’s
gaze exactly 23 degrees or 51 degrees
during the broad H test
40 degrees to the right or left is enough to
detect any limitation of movement
Muscles and their Fields of
Action
Right-hand elevator: muscle that turns the
eye upward when the eye is already
looking to the right (RSR and LIO)
Right-hand depressor: muscle that turns
the eye downward when the eye is already
looking to the right (RIR and LSO)
Muscles and their Fields of
Action
Left-hand elevator: muscle that turns the
eye upward when the eye is already
looking to the left (LSR and RIO)
Left-hand depressor: muscle that turns the
eye downward when the eye is already
looking to the left (LIR and RSO)
Muscles and their Fields of
Action
Example: A patient is asked to direct gaze
23 degrees to the right and up, any
limitation in movement of OD is due to
problem with RSR
Muscles and Their Fields of Action
Broad H Test
Look for lags or overshoots at various
diagnostic positions of gaze
Look for smooth and accurate pursuit
movements
Look for any gaze restrictions or
overactions of muscle in the 9 positions
Look for comitancy
Comitancy
When deviation of the visual axes remains
constant in all fields of gaze, there is
comitancy
When deviation of the visual axes changes
with field of gaze, there is noncomitancy
Comitancy
Check for comitancy by moving the target
to different positions of gaze, while
keeping the patient steady
In general, a patient with EOM paresis is
incomitant
Gaze Restriction
Overaction of Muscle
Saccade Test
Test set-up is the same as for the broad H
test
Direct patient to look quickly from positions
8 to 2, and then back to 8
Repeat rapid shifts of gaze from positions
6 to 5, and then back to 6
Look for accuracy of movement (i.e.,
overshoots and undershoots)
Saccade Test
Recording
Expected Findings
SAFE
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Smooth
Accurate
Full
Extensive