OS 212:
Dr. Marissa N. Valbuena
Locomotion and Sensation: Ophthalmology
Deviations of the Eye
EXAM
OUTLINE:
I.
Extraocular Muscle Anatomy
II. Motor Physiology of Extraocular Muscles
A. Axes of Fick
B. Gaze Positions
C. Muscle Actions
III. Eye Movements
A. Ductions
B. Contributory Actions of Muscles
C. Sherrington’s Law of Reciprocal Innervation
D. Versions
E. Vergence
F. Yoke Muscles
G. Hering’s Law of Motor Correspondence
H. Field of Action
IV. Binocular Vision
A. Amblyopia
B. Sensitive Period
C. Causes of Amblyopia
D. Diagnostic Methods
E. Fixation Capability
F. Therapy
G. Prevention
V. Strabismus
A. Classification of Strabismus
B. Patient Examination
C. Common Types of Comitant Strabismus
D. Common Types of Incomitant Strabismus
2.
Z axis (abduction and adduction)
o Vertical axis
o For voluntary horizontal movements
o Forms Listing’s equatorial plane
3.
Y axis (intorsion and extorsion)
o Axis passing through the center of the pupil – from
back to front
o Perpendicular to Listing’s plane
1
Gaze Positions
1. Primary Position – eyes looking straight ahead with the
head in a straight position
2. Secondary Positions – straight up, straight down, left gaze,
and right gaze
Primary position
Figure 1. Secondary Positions
3.
EXTRAOCULAR MUSCLE ANATOMY
Tertiary Positions – 4 oblique positions of gaze; up right,
up left, down right, down left
Primary position
The eye is unique among the body’s sensory organs because it
is capable of independent movement.
Extraocular Muscles: 4recti and 2obliques

Contain:
Slow tonic muscle fibers: for holding gaze
Fast muscle fibers: for rapid extreme gaze
Figure 2. Tertiary Positions
4.
EOM Innervations

Oculomotor Nerve (CN III)
o Superior division – superior rectus, levatorpalpebrae
o Inferior division – medial rectus, inferior oblique,
inferior rectus

Trochlear nerve (CN IV) – superior oblique

Abducens nerve (CN VI) – lateral rectus

High ratio of nerve fibers to muscle fibers (1:3 to 1:5)
compared to other skeletal muscles (1:50 to 1:125) allows
for more accurate control of eye movement
USEFUL MNEMONICS: SO4, LR6, ATR3 (all the rest yan, ok?)
Spiral of Tillaux
o Line of attachment of 4recti muscles to the sclera
o Distance between insertion of recti muscles to the limbus
o Important in locating muscles during surgery
See Appendix A: Table 1. Extraocular Muscles
MOTOR PHYSIOLOGY of EOM
Axes of Fick
1. X axis (elevation and depression)
o Transverse axis passing through the center of the eye
at the equator
o For voluntary vertical rotations of the eye
o Also for involuntary torsional movements
o Forms Listing’s equatorial plane, which passes
through the center of rotation(with Z axis)
Cardinal Positions – positions that isolate the individual
actions of extraocular muscles
Primary position
Figure 3. Cardinal Positions
To check for:
A. full movement of the eye to right or left
DAPAT 9:00 / 3:00 limbus touches the lateral canthus
B. full movement of the eye to oblique positions
CHECK distance between 12:00 / 6:00 limbus with the upper
& lower lid
* When checking for down gaze, LIFT the upper eyelids to see
the superior portion of the sclera (but, be gentle, ok?).
Muscle Actions
1. Primary actions – MAJOR effect on the position of the eye
when muscle contracts while the eye is in primary position
2. Secondary and tertiary actions – additional effects on the
position of the eye in primary position
See Appendix B: Table 2. Action of Extraocular Muscles from
the primary position
EYE MOVEMENTS


The eye can be moved about 50O in each direction from
the primary position
However, the eyes usually move only 15-20O from primary
position before head movement occurs (galawgalawparadimgDVT, hahaha!)
Page 1 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
OS 212:
Locomotion and Sensation: Ophthalmology
Dr. Marissa N. Valbuena
Deviations of the Eye
1.
2.
EXAM
Ductions (MONOCULAR movements of the eye)

Adduction – nasal rotation

Abduction – temporal rotation

Elevation – upward rotation

Depression – downward rotation

Intorsion (incycloduction) – nasal rotation of the
superior portion of the vertical corneal meridian

Extorsion (excycloduction) – temporal rotation of the
superior portion of the vertical corneal meridian
8.
Contributory Actions of Muscles

Agonist – primary muscle moving the eye in a given
direction

Synergist – muscle in the same eye as the agonist
that assists the agonist produce the same movement

Antagonist – muscle in the same eye as the agonist
that acts in the direction opposite to that of the
agonist
BINOCULAR VISION
NOTE: Agonists/Antagonists are in the SAME eye!

3.
Sherrington’s Law of Reciprocal Innervation

An increased innervation and contraction of a given
extraocular muscle is accompanied by a reciprocal
decrease in innervation and contraction of its
antagonist

Otherwise, innervation and contraction of both
agonist and antagonist will cancel out each other and
result in no eye movement (the globe might retract
BACKWARDS, oh no!)
4.
Versions (Conjugate BINOCULAR eye movements)

Same direction of both eye movements in a gaze
5.
Vergens

Disjugate binocular eye movements

Two eyes move in different directions

Two types
o Convergence – accommodation for near objects,
both eyes move medially
o Divergence – both eyes move temporally
6.
Yoke Muscles

Partner muscles in each eye that are prime movers of
their respective eyes in a given direction of gaze
NOTE: Yoke muscles are in DIFFERENT eyes!
RSR
LIO
RLR
LMR
RMR
LLR
R
RIO
RIO
LSR
LSR
RMR
LLR
RSO
LIR
L



A.
Distance of 50 to 65 mm between the eyes – causes
different image to be seen in each eye, which is fused in
the brain to form a stereoscopic image
Visual axis – imaginary line connecting a point in space
with the fovea
Binocular fixation
o Both eyes must be directed simultaneously to the
same object
o Visual axes must intersect at a single point
Normal development of stereoscopic vision requires
binocular, simultaneous use of each fovea during the
critical period early in life
Amblyopia

Reduced visual acuity, either unilaterally or
bilaterally, not justified by other organic defects

Usually caused by:
media opacities
high refractive errors
anisometropia (difference in refractive error of 2
eyes), or
ocular misalignment (strabismus) during visual
immaturity (poor eye vision)
Studied by neurophysiologists Hubert and Weisel, earning them
the Nobel Prize
o
The researchers sutured lids of newborn kittens and looked
for the effects on the cortex
o
All cortical cells are potentially connectible with the eye
o
If both eyes are used or are functioning well, the number of
cells connected to each are equal, so there is equal
functional capability in both eyes
o
However, when there is unequal usage or functioning, such
as when one eye predominates, the cortical cells in the
nonfunctioning or unused eye are stolen by the former,
leading to reduced visual functional capability of the latter
o
This process of “competition” is reversible within the first
part of the sensitive period
2.
Figure 4. Cardinal Positions and Yoke Muscles
7.
Field of Action

Eye direction when a muscle contracts
o whenmedial rectus contracts, eye direction is
inward, thus the field of action of the medial
rectus is inward turning of the eye

Gaze position (effect of muscle is readily observed)
o when patient looks up from primary position,
the effects of both the superior rectus and the
inferior oblique are seen, therefore the field of
action of both muscles is upward turning of the
eye
o To check SUPERIOR RECTUS in isolation: make
the patient look up and to the right using the
right eye, thus another field of action of the
superior rectus is the upward and temporal
movement of the eye
Hering’s Law of Motor Correspondence

Equal and simultaneous innervation flows to the yoke
muscles concerned in the desired direction of gaze
Sensitive Period

The visual system is sensitive within a given period
from birth to stages in infancy

Treatment for amblyopia is effective when given
during the sensitive period

Earlier treatment  better results  shorter length
of treatment

Duration not exactly defined in humans (since
experiment cannot be done in humans), but is
thought that it is from birth until 8-9 years
Page 2 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
1
OS 212:
Locomotion and Sensation: Ophthalmology
Dr. Marissa N. Valbuena
Deviations of the Eye
EXAM
1
When misalignment is large and constant (regardless
of age)
Classification of Strabismus
1. According to direction of deviation
o Horizontal – esodeviation, exodeviation
o Vertical – hyperdeviation, hypodeviation
o Torsional – excyclodeviation, incyclodeviation
2. According to age of onset
o Congenital / infantile – documented prior to 6
months
o Acquired
3. According to fusion status – whether the deviation
can be controlled by fusion mechanisms
o Phoria – latent deviation which can be controlled
by fusion mechanisms so that under binocular
conditions, the eyes remain aligned
o Intermittent phoria or tropia – fusion control
present part of the time
o Tropia – manifest deviation in which fusion
control is not present
4. According to variation of deviation with gaze position
or eye fixation
o Comitant
o Incomitant
5. According to fixation
o Alternating – spontaneous alteration of fixation
from one eye to the other
o Monocular – preference for fixation with one
eye
b.
3.
4.
Causes of Amblyopia

Strabismus

Anisometropia
o Difference between refractive errors in one eye
and in the other

Form deprivation
o Complete ptosis, unilateral occlusion or
atropinization, media opacities
o Uncorrected bilateral high hypermetropia
o Astigmatism (meridionalamblyopia)
o Nystagmus
A.
Diagnostic Methods
Visual Acuity Testing
o Difference of at least two lines of the chart
o Test the best VA of the good eye
o Measure both LINE ACUITY (Snellen) and LETTER
ACUITY (chart with individual letters)
o Usually letter acuity is better, because children
don’t get confused
NOTE: Letter acuity gets a BETTER VA than line acuity!
5.
Fixation Capability

If with severe unilateral amblyopia, the eye is
incapable of fixation

Indirect signs once organic pathology has been ruled
out:
o Occlusion of good eye leads to crying or violent
reactions
o No free alternation of fixation
6.
Therapy

Treat underlying cause (EOR, cataract)

Compel the child to use the poor eye by
patching(occlusion of) the good eye. If child needs
glasses, wear glasses on top of the patch
7.
Prevention

Early detection by pediatrician and family doctor

Referral of patients with predisposing factors
o Unable to cope with copying from blackboard
STRABISMUS




Abnormal ocular alignment
Orthophoria / orthotropia
o Ideal alignment
o Eyes are aligned in all directions of gaze at all
distances even after occluding one eye
Heterophoria
o Latent tendency to misalign
o Esophoria, exophoria, hypophoria, hyperphoria
Heterotropia – manifest misalignment
o Esotropia – inward deviation
o Exotropia – outward deviation
Pseudoesotropia

One of the most common reasons why an ophthalmologist
is asked to evaluate an infant or child (to assure the
parents that their child is okay, pinch the nasal bridge,
awwww!)

False appearance of esotropia when the visual axes are
aligned accurately

Causes:
a. Flat broad nasal bridge
b. Prominent epicanthal fold (upper eyelid)
c. Narrow interpupillary distance

As the child grows, nasal bridge becomes prominent
(aging, less manifested), epicanthal fold is displaced, and
the eyes look more normal

Parents observe that when the child looks to one side, the
eye almost disappears from view (due to broad nasal
bridge and lid)

Once confirmed, reassure parent that child will outgrow
the pseudoesotropia, but true esotropia can develop later
so tell parent to come back if misalignment persists

Reassessment necessary if apparent deviation does not
improve
B.
NOTE: phoria = tendency / tropia = with obvious manifestation
Ocular Alignments in Infants

Infants are rarely born with eyes properly aligned. During
the first month, alignment may vary intermittently from
esotropia to orthotropia to exotropia

Ocular development in first month of life does not
necessarily indicate an abnormality

Signs of strabismus (MOMMY, WHEN TO WORRY???)
a. When misalignment persists beyond 3 months of age
Patient Examination
History

Common chief complaints
a. Duling
b. Banlag
c. Watches TV up close
d. Difficulty with schoolwork
e. In adults – diplopia (double vision)

Age of onset
a. Infantile (<6 months)
b. Acquired (>6 months)
o Document onset with photograph
Page 3 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
OS 212:
Locomotion and Sensation: Ophthalmology
Deviations of the Eye







EXAM

Associated eye complaints
o Diplopia
o Blurring of vision
Antecedent or concurrent illness – strabismus may be
associated with systemic illnesses
a. Thyroid disease – Grave’s ophthalmopathy
b. Diabetes mellitus
c. Myasthenia gravis
d. Neurologic conditions – cerebrovascular disorders
and CNS space-occupying lesions
Trauma
Previous consultation, medications, and treatment
o Patching
o History of wearing glasses
o Surgery
Maternal and birth history – premature births are
associated with high EOR and associated esotropia
Developmental history
Family history – sometimes, strabismus can occur in
families
3.
b.
Prism test (Krimsky test)
o more accurate compared to Hirschberg test
o add prism until light is at the center of the pupil
c.
Cover tests
o Depends on the patient’s ability to maintain constant
fixation on an accommodative target
o Cover-uncover test

Establishes the presence of either a manifest
deviation (heterotropia) or a latent deviation
(heterophoria)

You can elicit hidden misalignment because you
allow binocular vision in between covering eyes

Patient is Hirschberg normal but upon doing this
test, there is movement, meaning there is
misalignment

In orthophoric patient, covering one eye will
result in NO movement

In esotropia, covering the esotropic eye results
in the fixation (outward movement) of the other
eye (uncovered)

In exotropia, covering the exotropic eye results
in the fixation (inward movement) of the other
eye (uncovered)
o Alternate cover test

Measures the extent of deviation
Transfer the cover without patient being
binocular; can’t differentiate phoria from tropia;
aid in getting maximum amount of deviation
a.
Congenital Esotropia or Infantile Esotropia (Cross
Eye)

Noted shortly after birth up to 6 months of age

Esodeviation is big and constant

Cross fixation – infant uses right eye to look at
left visual field and vice versa

Overaction of inferior obliques elevation on
adduction

Latent nystagmus

Refraction is usually normal for age

Management: correct EOR
o Treat amblyopia
o Surgical
o Weaken medial rectus
o Muscle recession – weakens muscle by
making it more loose or slack
o Muscle resection – strengthens muscle by
removing muscle segments
b.
Refractive Accommodative Esotropia

Onset at 2-3 years

Uncorrected hyperopia

Excess accommodation to clear blurred vision
leads to excess convergence

Fusional divergence not sufficient

Convex or plus lenses are prescribed to correct
the hyperopia
c.
Sensory Exotropia or Esotropia

Esodeviation seen in patients with monocular or
binocular conditions that prevent good vision –
e.g. corneal opacity, cataract, retinal scars,
inflammation, tumors, optic neuropathy,
anisometropia

May occur in eyes that do not see well for any
reason

Treatment modalities
o Correction of cause of poor vision
o Full cycloplegic refraction
(akacyclorefraction)  paralyzes the ciliary
body to determine the maximal deviation of
the eye
o Muscle surgery to correct deviation
d.
Intermittent Exotropia

Outward deviation starts out as intermittent

Vision usually good for both eyes

Manifests when patient is fatigued, sleepy or
inattentive

Frequency and duration of deviation may
increase as patient grows older

Surgical management
o Weaken lateral rectus (RECESSION),
strengthen medial rectus (RESECTION)
e.
Sensory Exotropia

An eye that does not see well for any reason
may turn outward
Nonverbal or infant – ability to fixate, crying when good
eye is covered
Tests for Ocular Alignment
a. Corneal light reflex – Hirschberg method
o Shine a light in between the patient’s eyes 2 feet
from the patient, instructing patient to look into the
light
o Observe relative placement of light reflex
o As reflex is displaced, magnitude is increased
o 1 mm of deviation is equivalent to 1 degree of
displacement
1
Common Types of Comitant Strabismus

Same amount no matter where patient looks on what
eyes fixates on

Deviation does not vary with direction of gaze or
fixating eye
Tests for Visual Acuity

If verbal patient, objective VA assessment:
Snellen’s chart
Pictures
Shapes
Tumbling E (used for illiterate or pediatric patients)
H-O-T-E-X chart (asked the patient to point which letter is
he/she is seeing)

Dr. Marissa N. Valbuena
Page 4 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
OS 212:
Locomotion and Sensation: Ophthalmology
Deviations of the Eye

4.
Dr. Marissa N. Valbuena
EXAM
Surgical management
Common Types of IncomitantStrasibmus

Deviation varies with direction of gaze or fixating eye
a.
Paralytic Strabismus

Limitation of action of involved muscle

Deviation is bigger when the involved eye is
fixating and in the direction of action of the
involved muscle

Lateral rectus paralysis is most common due to
CN VI nerve palsy
b.
Thyroid Orbitopathy

Restrictive rather than paralytic (restriction in
the elevation of the eye: INFERIOR RECTUS
commonly involved)

Deposits of inflammatory cells in muscle (usually
inferior rectus) makes it stiff
c.
Duane’s Syndrome

Congenital motility disorder, usually unilateral

Limited abduction, adduction, or both

Globe retraction and narrowing of palpebral
fissure on adduction

Possible upshooting or downshooting of the eye

Face turn is done to use both eyes together

Corrective muscle surgery for treatment
***FIRST EVER GREETINGS (dikasikami KJ, okay?)***
Nico:
RIP CORY.
At sa mga naniniwala na marunong ako mag bake,
bibigyan ko kayo ng Cheesecake pag nakagawa na ako.
Ton: Hello, 2013!Ang sarap ng buhay ng 2nd year. Oh sem break,
kailan ka badadating? 2 months pa lang, parang 10 years na ang
lumipas ah. Tsktsk! Violation of human rights na ito. Haha!
Perosalamat sa mga alphamates ko and special mention to
AnnTOT& Ian, di ko nanapapansin ang kaTOXICan ng 2nd year
dahil sa inyo. You make my life easier and less stressful (as a
treatment to my cholinergic urticaria, haha!) Thank you 4
everything! Oh researchmates, gawin na nating business ang
research natin! Davao, here we come! Yay!
Mary: Hello 2013! Hello Block A! A special hi to my Block B
friends na sobrang namimiss ko na. Lunch tayo soon, please? KAn, Trebs (yes, pati ikaw though di ko kinuwento sa iyo),
Gerald, and Mr. Barnes (oops, Migs nga pala), thanks so much!
I’m coping, or at least I think I am. Josh, be happy na, love ka
namin! Anyway, 2013, God Bless sa exams! 
K-an: Hello friends! Yay, august na! malapit na mag-october! 
I miss you block B! Hugs to Tin, Kirth, Tracy, alphamates,
agapemates, RSO, and everyone!  We can do this block A!
God bless!
Special thanks to Josh Abejero and Nico Agustin for lending us
their laptop. 
(Insert picture here.) hahaha!
Page 5 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
1
OS 212:
Dr. Marissa N. Valbuena
Locomotion and Sensation: Ophthalmology
Deviations of the Eye
EXAM
Appendix A. Table 1. Extraocular Muscles
Muscle
Origin
Insertion
Medial Rectus
Annulus of Zinn
Lateral Rectus
Annulus of Zinn
Superior Rectus
Annulus of Zinn
Inferior Rectus
Annulus of Zinn
5.5 from medial
limbus
6.9 from lateral
limbus
7.7 from superior
limbus
6.5 from inferior
limbus
Superior Cblique
Orbit apex above
Annulus of Zinn
(functional origin at
trochlea)
Behind lacrimalfossa
Inferior Oblique
Direction
of Pull
90°
Action from
Primary Position
Adduction
90°
Abduction
VI
23°
Elevation, Intorsion
Adduction
Depression,
Extorsion,
Adduction
Intorsion,
Depression,
Abduction
III
23°
Posterior equator at
superotemporal
quadrant
51°
Posterior to the
equator in inferotemporal quadrant
51°
Extorsion,
Elevation,
Abduction
Innervation (CN)
III
III
IV
III
Appendix B. Table 2. Actions of EOM from the Primary Position
Muscle
Medial
Rectus
Lateral
Rectus
Superior
Rectus
Inferior
Rectus
Superior
Oblique
Inferior
Oblique
Primary
Adduction
Secondary
Tertiary
Incycloduction /
Intorsion
Excycloduction /
Extorsion
Depression
Adduction
Abduction
Elevation
Depression
Incycloduction /
Intorsion
Excycloduction /
Extorsion
Elevation
Adduction
Abduction
Abduction
Appendix C. Table 3. Agonists with their Respective Synergists
and Antagonists
Agonists
Medial Rectus
Synergist
Superior Rectus
Inferior Rectus
Lateral Rectus
Superior Oblique
Inferior Oblique
Superior Rectus
Inferior Oblique
Medial Rectus
Superior Oblique
Medial Rectus
Inferior Rectus
Lateral Rectus
Superior Rectus
Lateral Rectus
Inferior Rectus
Superior Oblique
Inferior Oblique
Antagonists
Lateral Rectus
Superior Oblique
Inferior Oblique
Medial Rectus
Superior Rectus
Inferior Rectus
Inferior Rectus
Superior Oblique
Superior rectus
Inferior Oblique
Inferior Oblique
Superior Rectus
Superior Oblique
Inferior Rectus
Page 6 of 6
TUESDAY | August 04, 2009
Ton Nico Mary K-an
1