Introduction to Ocular Motility Extraocular Muscles EOM ...

Introduction to Ocular Motility
Diana J. Shamis, CO, COMT, MHSE
University of Florida
EOM Abbreviations
IR - Inferior rectus
SR - Superior rectus
LR - Lateral rectus
MR - Medial rectus
SO - Superior oblique
IO - Inferior oblique
Rectus muscle insertions
Extraocular Muscles
Innervation of EOM
Oculomotor nerve, CN III
Inferior Inferior division: MR, IR, IO
Superior Superior division: SR, levator
Trochlear nerve, CN IV
Superior Superior oblique
Abducens nerve, CN VI
Lateral Lateral rectus
1

Diagnostic Positions of Gaze
2

Ductions and Versions
Versions - Movement of both eyes
Amplitude, smoothness, palpebral fissure
height, pupil size, oscillations.
Ductions – Movement of one eye
If versions abnormal
Improvement on ductions suggests
paretic process
Normal Versions
Normal Versions
Herring’s Law of Equal
Innervation
When an impulse goes to a muscle to
contract, an equal impulse goes to it’s
contralateral synergist (yoke muscle).
Sherrington’s Law of
Reciprocal Innervation
When an impulse goes to a muscle to
contract, an equal and opposite
impulse to relax goes to it’s ipsilateral
antagonist.
CN VI palsy (LR)
Limitation of abduction
3

Brown syndrome
Limited elevation in adduction
SO palsy
Limited depression in adduction
Over-action of IO
Duane - Type I
Incomitant ET due to 6th CN palsy.
Abduction deficit to the effected side.
Narrowing of the palpebral fissures on adduction of the
effected eye.
CN III palsy
Limited upgaze, downgaze, & adduction
V pattern XT
Recording Under-actions and
Over-actions
50%
70 %
+ 3
-2
4

Vergence
Disconjugate movements of the eyes.
Movement in opposite directions.
Convergence
Convergence – Both eyes turn in
Divergence Divergence – Both eyes turn out
Vertical Vertical vergence – One eye moves up,
the other down
Strabismus
Ocular misalignment that prevents bifoveal
fixation.
Non-parallel Non parallel visual axes.
Fixation
Central Fixation
Using Using the fovea to fixate
Eccentric Fixation
Using Using a non-foveal non foveal retinal point to fixate
Bifoveal fixation
Using Using both foveas to fixate the same
object at the same time.
Convergence amplitudes
Measure with base out
prism bar at distance
and near.
Minimum normal
20 prism diopter at
near
12 at distance
Fixation
Maintaining the position of the eye so
that the image of the object of regard
falls on the fovea.
Fovea
Central Fixation
5

Angle Kappa
Heterotropia (Tropia)
Deviation of an eye
which is present under
normal visual
situations.
A “Manifest”
deviation
Not necessarily visible
to casual observation.
Heterophoria (Phoria)
Latent tendency for the eyes to
deviate, which is controlled by fusion.
f
X
f
f
X
X
f
X
f
Eccentric Fixation
Dragged Macula
Heterotropia
Not always apparent to casual observation.
Intermittent deviation
A deviation which is sometimes a phoria
and sometimes a tropia.
May vary with position of gaze, distance
from the patient, or fatigue.
6

Intermittent Strabismus
X(T)
Strabismus abbreviations
E – Esophoria ET – Esotropia
X – Exophoria XT – Exotropia
H – Hyperphoria HT – Hypertropia
ht – hypophoria ht – hypotropia
Bracketed (T) indicates intermittent tropia
Ex: X (T) - Intermittent exotropia
Cover- Uncover Test
Detecting a Heterotropia
Differentiating a Tropia from a Phoria
Requires ability to fixate with either eye
Alternating Strabismus
Patient alternates which eye is the
straight eye and which eye is deviated.
Detection and Measurement of
Strabismus
Cover - uncover test
Hirschberg corneal reflex test
Krimsky
Prism and alternate cover test
Maddox rod
Cover-Uncover Test
Insure adequate fixation
7

1.
Cover-Uncover Test
Observe eye movement as the
unoccluded eye recovers fixation.
Esotropia Esotropia - Eye pulls out
Exotropia Exotropia - Eye pulls in
Hypertropia Hypertropia - Eye pulls down
Hypotropia Hypotropia - Eye pulls up
Left hypotropia. OD fixing.
3.
Cover-Uncover Cover Uncover Test
Test - Vertical
Vertical
Right Hypertropia. OS fixing.
2.
4.
Cover fixing eye (OD)
Hypotropic OS pulls up.
OD under cover deviates up.
Cover fixing eye (OS)
Hypertropic OD pulls down
OS under cover deviates down
Measuring the deviation
Use PACT if possible
Use Krimsky if patient cannot fixate well.
If only one eye moves - place prism in front of eye
with restricted motion.
1.
3.
Cover-uncover test: Esotropia
LET. OD fixing.
Cover is removed.
Neither eye moves.
Bifovial fixation
2.
4.
Cover deviated OS.
OD does not move.
Cover fixing eye.
Deviated OS pulls out.
OD under cover deviates in.
Cover-uncover test: Exophoria
1. 2.
3.
Cover is removed, deviated
eye moves in to regain fusion.
Cover left eye.
Eye under cover deviates out.
Measuring Strabismus
4.
Cover right eye.
Eye under cover deviates out.
PACT - Prism Alternate Cover Test
Most accurate, requires good fixation
Hirschberg and Krimsky
If poor vision, poor fixation, nystagmus
Young children, inattention
Maddox rod
useful for measuring small vertical deviations
in cooperative patient.
8

Hirschberg Corneal Light
Reflex Test
Estimate of deviation by observing
symmetry of corneal light reflexes.
Least accurate means of measurement.
1 mm displacement = 15
Right Esotropia
Light reflex is out because the eye
is turned in.
Right Hypertropia
Light reflex is down, because the
eye is up.
Hirschberg estimate
Corneal light reflex test
Estimate of deviation
based on amount of
displacement of corneal
light reflex.
1 mm displacement =
15 deviation
30 ET
60 ET
90 ET
Left Exotropia
Light reflex is in, because the
eye is turned out.
Krimsky Prism Reflex
Test
Estimate of the deviation by aligning
the corneal light reflexes with prisms.
Light reflexes should be symmetrical,
not necessarily centered.
9

Krimsky Prism Reflex Test
Prisms are added until light reflexes
are symmetric.
Krimsky: Over-correction
Prism and Alternate Cover Test
Movement of the eyes is neutralized with
prisms.
ET ET– Eye moves out – Base out
XT– XT Eye moves in -Base Base in
HT– HT Eye moves down – Base down
ht - Eye moves up – Base up
Prism position
ET – Light reflex out - Base out
XT – Light reflex in - Base in
HT– HT Light reflex down -Base Base down
ht – Light reflex up -Base Base up
Prism and Alternate Cover Test
Patient must be
able to fixate OU.
Cross cover and
add prisms until
motion is
neutralized.
PACT - Esotropia
X
1. 2.
f
X
f
f
3.
X
f
f
X
f
10

X
1. 2.
f
PACT - Exophoria
f
3.
Maddox Rod
Vertical cylinder -
patient sees
horizontal red line.
Use to measure HT.
Horizontal cylinders -
patient sees a vertical
red line. Use to
measure ET or XT.
f
Proper prism position
Parallel to floor of the orbit
Perpendicular to the line of sight
X
f
f
X
f
Maddox Rod
Patient looks at a light with Maddox Rod over one
eye.
Can not differentiate between phoria and tropia.
Measures latent or manifest deviation.
Maddox rod responses
Maddox Rod over right eye
Ortho Response
Left Hyper
Right Hyper
Exodeviation
Esodeviation
Right gaze - Left gaze
11

Up gaze and Down gaze
Right
Gaze
Recording the Results
PACT, sc: 10 LHT’
10 LHT
15 LHT
5 ET
20 LHT
8 ET
10 LHT
10 LHT
5 ET
10 LHT
8 ET
6 LHT
4 LHT
5 ET
2 LHT
8 ET
4 LHT 15LHT
Childhood Strabismus
Horizontally Comitant Strabismus
Infantile Infantile Esotropia
Accommodative Accommodative Esotropia
Intermittent Intermittent Exotropia
Left
Gaze
Head tilt - right and left
Only needed in HT
Comitant vs. Incomitant
Comitant
Infantile ET
Incomitant
Right LR palsy
60 ET 60 ET 60 ET 45 ET 25 ET OT
Comitant Esotropia
12

Acquired strabismus
Palsies and Restrictions
Incomitant deviations
Deviation Deviation is different in different
positions of gaze.
10 LHT
15 LHT
5 ET
20 LHT
8 ET
10 LHT
10 LHT
5 ET
8 LHT
8 ET
6 LHT
4 LHT
5 ET
2 LHT
8 ET
Incomitant Strabismus
13