Extraocular Motility

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Extraocular MotilityExtraocular Motility

Walter Huang, ODWalter Huang, OD

Yuanpei UniversityYuanpei University

Department of OptometryDepartment of Optometry

Extraocular MusclesExtraocular Muscles

PurposePurpose To control the movement of the globeTo control the movement of the globe

Extraocular MusclesExtraocular Muscles

Rectus musclesRectus muscles Superior rectus muscle (SR)Superior rectus muscle (SR) Inferior rectus muscle (IR)Inferior rectus muscle (IR) Medial rectus muscle (MR)Medial rectus muscle (MR) Lateral rectus muscle (LR)Lateral rectus muscle (LR)

Oblique musclesOblique muscles Superior oblique muscle Superior oblique muscle

(SO)(SO) Inferior oblique muscle (IO)Inferior oblique muscle (IO)

Anterior View of Right EyeAnterior View of Right Eye

Superior View of Right OrbitSuperior View of Right Orbit

Action of muscles affected by globe Action of muscles affected by globe position in the ocular orbit and muscle position in the ocular orbit and muscle orientationsorientations

Posterior View of Right EyePosterior View of Right Eye

Medial RectusMedial Rectus

Along the medial aspect of the eyeball, the Along the medial aspect of the eyeball, the medial rectus muscle inserts at a point medial rectus muscle inserts at a point 5.5mm of the limbus5.5mm of the limbus

It is controlled by the oculomotor nerve It is controlled by the oculomotor nerve (cranial nerve III)(cranial nerve III)

Contraction of this muscle causes Contraction of this muscle causes adadduction of the eyeduction of the eye

Medial RectusMedial Rectus

AdAdductionduction

Lateral RectusLateral Rectus

Along the lateral aspect of the eyeball, the Along the lateral aspect of the eyeball, the lateral rectus muscle inserts at a point lateral rectus muscle inserts at a point 7.0mm of the limbus7.0mm of the limbus

It is controlled by the abducens nerve It is controlled by the abducens nerve (cranial nerve VI)(cranial nerve VI)

Contraction of this muscle causes Contraction of this muscle causes ababduction of the eyeduction of the eye

Lateral RectusLateral Rectus

AbAbductionduction

Inferior RectusInferior Rectus

Along the inferior aspect of the eyeball, the Along the inferior aspect of the eyeball, the inferior rectus muscle inserts at a point inferior rectus muscle inserts at a point 6.5mm of the limbus6.5mm of the limbus

When the eyeball is positioned 23 degrees When the eyeball is positioned 23 degrees outward in the orbit with respect to primary outward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes depression of the eyedepression of the eye

When the eyeball is positioned 67 degrees When the eyeball is positioned 67 degrees inward in the orbit with respect to primary inward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes excycloduction of the eyeexcycloduction of the eye

When the eyeball is positioned straight When the eyeball is positioned straight ahead in the orbit with respect to primary ahead in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes adadduction of the eyeduction of the eye

Contraction of this muscle causes Contraction of this muscle causes depression, excycloduction, and depression, excycloduction, and adadduction duction of the eyeof the eye

Position of IR and SRPosition of IR and SR

Primary Action of IRPrimary Action of IR

DepressionDepression

Secondary Action of IRSecondary Action of IR

ExcycloductionExcycloduction

Tertiary Action of IRTertiary Action of IR

AdAdductionduction

Superior RectusSuperior Rectus

Along the superior aspect of the eyeball, Along the superior aspect of the eyeball, the superior rectus muscle inserts at a the superior rectus muscle inserts at a point 7.5mm of the limbuspoint 7.5mm of the limbus

When the eyeball is positioned 23 degrees When the eyeball is positioned 23 degrees outward in the orbit with respect to primary outward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes elevation of the eyeelevation of the eye

When the eyeball is positioned 67 degrees When the eyeball is positioned 67 degrees inward in the orbit with respect to primary inward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes incycloduction of the eyeincycloduction of the eye

When the eyeball is positioned straight When the eyeball is positioned straight ahead in the orbit with respect to the ahead in the orbit with respect to the primary gaze, contraction of this muscle primary gaze, contraction of this muscle causes causes adadduction of the eyeduction of the eye

Contraction of this muscle causes Contraction of this muscle causes elevation, incycloduction, and elevation, incycloduction, and adadduction of duction of the eyethe eye

Primary Action of SRPrimary Action of SR

ElevationElevation

Secondary Action of SRSecondary Action of SR

IncycloductionIncycloduction

Tertiary Action of SRTertiary Action of SR

AdAdductionduction

Superior ObliqueSuperior Oblique

The superior oblique muscle passes The superior oblique muscle passes through the trochlea and its insertion on through the trochlea and its insertion on the eyeball below the superior rectus the eyeball below the superior rectus muscle is at 51 degrees with respect to muscle is at 51 degrees with respect to primary gazeprimary gaze

It is controlled by the trochlear nerve It is controlled by the trochlear nerve (cranial nerve IV)(cranial nerve IV)

When the eyeball is positioned 39 degrees When the eyeball is positioned 39 degrees outward in the orbit with respect to primary outward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes incycloduction of the eyeincycloduction of the eye

When the eyeball is positioned 51 degrees When the eyeball is positioned 51 degrees inward in the orbit with respect to primary inward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes depression of the eyedepression of the eye

When the eyeball is positioned straight When the eyeball is positioned straight ahead in the orbit with respect to the ahead in the orbit with respect to the primary gaze, contraction of this muscle primary gaze, contraction of this muscle causes causes ababductionduction

Contraction of this muscle causes Contraction of this muscle causes incycloduction, depression, and incycloduction, depression, and ababduction duction of the eyeof the eye

Position of SO and IOPosition of SO and IO

Primary Action of SOPrimary Action of SO

IncycloductionIncycloduction

Secondary Action of SOSecondary Action of SO

DepressionDepression

Tertiary Action of SOTertiary Action of SO

AbAbductionduction

Inferior ObliqueInferior Oblique

The insertion of the inferior oblique muscle The insertion of the inferior oblique muscle is on the eyeball below the lateral rectus is on the eyeball below the lateral rectus muscle at 51 degrees with respect to muscle at 51 degrees with respect to primary gazeprimary gaze

When the eyeball is positioned 39 degrees When the eyeball is positioned 39 degrees outward in the orbit with respect to primary outward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes excycloduction of the eyeexcycloduction of the eye

When the eyeball is positioned 51 degrees When the eyeball is positioned 51 degrees inward in the orbit with respect to primary inward in the orbit with respect to primary gaze, contraction of this muscle causes gaze, contraction of this muscle causes elevation of the eyeelevation of the eye

When the eyeball is positioned straight When the eyeball is positioned straight ahead in the orbit with respect to the ahead in the orbit with respect to the primary gaze, contraction of this muscle primary gaze, contraction of this muscle causes causes ababductionduction

Contraction of this muscle causes Contraction of this muscle causes excycloduction, elevation, and excycloduction, elevation, and ababduction duction of the eyeof the eye

Primary Action of IOPrimary Action of IO

ExcycloductionExcycloduction

Secondary Action of IOSecondary Action of IO

ElevationElevation

Tertiary Action of IOTertiary Action of IO

AbAbductionduction

Functions of Extraocular MusclesFunctions of Extraocular Muscles

MuscleMuscle Primary Primary ActionAction

Secondary Secondary ActionAction

Tertiary Tertiary ActionAction

MRMR AdductionAdduction

LRLR AbductionAbduction

IRIR DepressionDepression ExcycloExcyclo

ductionduction

AdductionAdduction

Functions of Extraocular MusclesFunctions of Extraocular Muscles

MuscleMuscle Primary Primary ActionAction

Secondary Secondary ActionAction

Tertiary Tertiary ActionAction

SRSR ElevationElevation IncycloIncyclo

ductionduction

AdductionAdduction

SOSO IncycloIncyclo

ductionduction

DepressionDepression AbductionAbduction

IOIO ExcycloExcyclo

ductionduction

ElevationElevation AbductionAbduction

TerminologyTerminology

Duction: describes movement of Duction: describes movement of oneone eye eye AbductionAbduction AdductionAdduction Supraduction or elevationSupraduction or elevation Infraduction or depressionInfraduction or depression Incycloduction or intorsionIncycloduction or intorsion Excycloduction or extorsionExcycloduction or extorsion

Version: describes movement of Version: describes movement of twotwo eyes eyes in the in the samesame direction direction DextroversionDextroversion LevoversionLevoversion SupraversionSupraversion InfraversionInfraversion

Vergence: describes movement of Vergence: describes movement of twotwo eyes in eyes in oppositeopposite directions directions ConvergenceConvergence DivergenceDivergence

Version and VergenceVersion and Vergence

Near Point of ConvergenceNear Point of Convergence

Maximum convergence ability or NPC is Maximum convergence ability or NPC is measured by as part of confrontational measured by as part of confrontational testingtestingNPC = point of intersection of line of sight NPC = point of intersection of line of sight when eyes are maximally convergedwhen eyes are maximally convergedTheoretically, NPC should be measured Theoretically, NPC should be measured from center of rotation of eyesfrom center of rotation of eyesClinically, NPC is measured from the facial Clinically, NPC is measured from the facial planeplane

NPC break point (target becomes double) NPC break point (target becomes double) greater than 7cm is considered abnormalgreater than 7cm is considered abnormal

Average NPC is approximately 5cmAverage NPC is approximately 5cm

The recovery point (target becomes The recovery point (target becomes single) is expected to be within 10cmsingle) is expected to be within 10cm

A patient with reduced NPCA patient with reduced NPC Convergence insufficiency Convergence insufficiency Some presbyopesSome presbyopes SymptomsSymptoms

Diplopia, frontal headache, asthenopia, fatigue, Diplopia, frontal headache, asthenopia, fatigue, and reduced reading abilityand reduced reading ability

The patient may benefit from vision therapy or The patient may benefit from vision therapy or prism in reading Rxprism in reading Rx

Object Tracking MovementsObject Tracking Movements

Saccade: fast, step-like eye movement (up Saccade: fast, step-like eye movement (up to 1000 deg/sec) that places image of the to 1000 deg/sec) that places image of the target on the foveatarget on the fovea ReadingReading Looking from point A to BLooking from point A to B Fixating on a stationary targetFixating on a stationary target

Object Tracking MovementsObject Tracking Movements

Pursuit: slow, smooth-following movement Pursuit: slow, smooth-following movement (up to 30 deg/sec) that maintains image of (up to 30 deg/sec) that maintains image of the target on the foveathe target on the fovea Following a moving targetFollowing a moving target

Extraocular Motility TestingExtraocular Motility Testing

The most common test for extraocular The most common test for extraocular motility is the broad H testmotility is the broad H test

EOM testing is also part of confrontational EOM testing is also part of confrontational testingtesting

Extraocular Motility TestingExtraocular Motility Testing

PurposePurpose To investigate the integrity of the extraocular To investigate the integrity of the extraocular

muscles and their nervesmuscles and their nerves To assess the patient’s ability to perform To assess the patient’s ability to perform

version eye movementsversion eye movements To determine if strabismus is comitant (i.e., To determine if strabismus is comitant (i.e.,

deviation does not change with direction of deviation does not change with direction of gaze)gaze)

Broad H TestBroad H Test

A pursuit test done binocularly with A pursuit test done binocularly with penlight at a test distance of 30 to 40cmpenlight at a test distance of 30 to 40cm

It tests 9 positions of action, starting with It tests 9 positions of action, starting with primary positionprimary position

It tests It tests fields of action fields of action of the 6 extraocular of the 6 extraocular musclesmuscles

Field of action = direction where a Field of action = direction where a particular muscle has the greatest actionparticular muscle has the greatest action

Examples of fields of actionExamples of fields of action Right LR: field of action is the right-hand fieldRight LR: field of action is the right-hand field Right MR: field of action is the left-hand fieldRight MR: field of action is the left-hand field This is opposite for left LR and left MRThis is opposite for left LR and left MR

Position of SR and IRPosition of SR and IR

Action of SR and IRAction of SR and IR

SR and IR lie in a muscle plane that SR and IR lie in a muscle plane that makes a 23 degree angle with the straight makes a 23 degree angle with the straight ahead positionahead position

When the eye turns out 23 degrees, SR When the eye turns out 23 degrees, SR acts as a pure elevator, and IR acts as a acts as a pure elevator, and IR acts as a pure depressorpure depressor

Position of SO and IOPosition of SO and IO

Action of SO and IOAction of SO and IO

SO and IO lie in a muscle plane that SO and IO lie in a muscle plane that makes a 51 degree angle with the straight makes a 51 degree angle with the straight ahead directionahead direction

When the eye turns in 51 degrees, SO When the eye turns in 51 degrees, SO acts as a pure depressor, and IO acts as a acts as a pure depressor, and IO acts as a pure elevatorpure elevator

It is not necessary to direct the patient’s It is not necessary to direct the patient’s gaze exactly 23 degrees or 51 degrees gaze exactly 23 degrees or 51 degrees during the broad H testduring the broad H test

40 degrees to the right or left is enough to 40 degrees to the right or left is enough to detect any limitation of movementdetect any limitation of movement

Muscles and their Fields of Muscles and their Fields of ActionAction

Right-hand elevator: muscle that turns the Right-hand elevator: muscle that turns the eye upward when the eye is already eye upward when the eye is already looking to the right (RSR and LIO)looking to the right (RSR and LIO)

Right-hand depressor: muscle that turns Right-hand depressor: muscle that turns the eye downward when the eye is already the eye downward when the eye is already looking to the right (RIR and LSO)looking to the right (RIR and LSO)

Left-hand elevator: muscle that turns the Left-hand elevator: muscle that turns the eye upward when the eye is already eye upward when the eye is already looking to the left (LSR and RIO)looking to the left (LSR and RIO)

Left-hand depressor: muscle that turns the Left-hand depressor: muscle that turns the eye downward when the eye is already eye downward when the eye is already looking to the left (LIR and RSO)looking to the left (LIR and RSO)

Example: A patient is asked to direct gaze Example: A patient is asked to direct gaze 23 degrees to the right and up, any 23 degrees to the right and up, any limitation in movement of OD is due to limitation in movement of OD is due to problem with RSRproblem with RSR

Muscles and Their Fields of ActionMuscles and Their Fields of Action

Look for lags or overshoots at various Look for lags or overshoots at various diagnostic positions of gazediagnostic positions of gaze

Look for smooth and accurate pursuit Look for smooth and accurate pursuit movementsmovements

Look for any gaze restrictions or Look for any gaze restrictions or overactions of muscle in the 9 positionsoveractions of muscle in the 9 positions

Look for comitancyLook for comitancy

ComitancyComitancy

When deviation of the visual axes remains When deviation of the visual axes remains constant in all fields of gaze, there is constant in all fields of gaze, there is comitancycomitancy

When deviation of the visual axes changes When deviation of the visual axes changes with field of gaze, there is with field of gaze, there is noncomitancynoncomitancy

ComitancyComitancy

Check for comitancy by moving the target Check for comitancy by moving the target to different positions of gaze, while to different positions of gaze, while keeping the patient steadykeeping the patient steady

In general, a patient with EOM paresis is In general, a patient with EOM paresis is incomitantincomitant

Gaze RestrictionGaze Restriction

Overaction of MuscleOveraction of Muscle

Saccade TestSaccade Test

Test set-up is the same as for the broad H Test set-up is the same as for the broad H testtest

Direct patient to look quickly from positions Direct patient to look quickly from positions 8 to 2, and then back to 88 to 2, and then back to 8

Repeat rapid shifts of gaze from positions Repeat rapid shifts of gaze from positions 6 to 5, and then back to 66 to 5, and then back to 6

Look for accuracy of movement (i.e., Look for accuracy of movement (i.e., overshoots and undershoots)overshoots and undershoots)

Saccade TestSaccade Test

RecordingRecording

Expected FindingsExpected Findings

SAFESAFE SSmoothmooth AAccurateccurate FFullull EExtensivextensive

Extraocular Motility

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