Strabismus squint evaluation and management

Strabismus by Professor Mazhry
STRABISMUS
DR. ZIA UL MAZHRY
FRCS(EDIN), FRCS(GLASG), FCPS(PAK)
ASSTT PROFESSOR CONSULTANT OPHTHALMOLOGIST

APAO BEIJING 2010

DISCUSSION PLAN
1. Introduction
2. Anatomy
3. Classification
4. Clinical Examination
5. Treatment Objectives
6. ET management
7. XT management
8. Rare Syndromes

SECTION 1
INTRODUCTION

STRABISMUS
*Squint
*Crossed Eyes

STRABISMUS
Definition:
Misalignment of the eyes

DEFINITION
• Squint is a disorder in which one eye
misaligns with the other when focusing
in a primary direction of gaze. It is an
imbalance in the normal tone or
coordination of one or more extra
ocular muscle which results in a
manifest deviation of the affected eye.

EXTRAOCULAR
MUSCLES

INTRODUCTION
EOM
Cardinal Axis of Gaze

SECTION 2
ANATOMY OF EOM

ANATOMY OF THE EOM’S
How many?

Six Extraocular muscles surround each eye:
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus
Superior Oblique
Inferior Oblique

What are their actions??

Medial Rectus Action??

Medial Rectus Action??
Adduction

Lateral Rectus Action??

Lateral Rectus Action??
Abduction

Superior Rectus Action??

Elevation

Elevation
Adduction

Elevation
Adduction
Intorsion

Inferior Rectus Action??

Depression

Depression
Adduction

Depression
Adduction
Extorsion

Superior Oblique Action??

Intorsion

Intorsion
Depression

Intorsion
Depression
Abduction

Inferior Oblique Action??

Extorsion

Extorsion
Elevation

Extorsion
Elevation
Abduction

The two Obliques are Abductors

The two Recti are Adductors

The two Superiors are Intorters

The two Superiors are Intorters
The two Inferiors are Extorters

Origin
A common tendinous ring (annulus of
Zinn)

Insertion

Blood supply
Each muscle is supplied by two Anterior Ciliary
Arteries except the Lateral Rectus which is only
supplied by one.

Nerve supply

Nerve supply
Third
Fourth
Sixth

Nerve supply
Third: MR, IR, SR, IO
Fourth
Sixth

Nerve supply
Fourth: Superior Oblique
Sixth

Nerve supply
Fourth: Superior Oblique
Sixth: Lateral Rectus

CHINESE PUPPET SHOW

SECTION 3
CLASSIFICATION OF STRABISMUS

CLASSIFICATION
1. Direction of deviation:
- convergent (esotropia)
- divergent (exotropia)
- hypodeviation
- hyperdeviation
2. Comitancy:
- comitant or non paralytic
- incomitant or paralytic

CLASSIFICATION
3. Constancy:
- intermittent
- constant
4. Onset:
- childhood (congenital)
- adult (acquired)
5. Unilateral or Alternating

CLASSIFICATION
6. Apparent (psuedostrabismus)
Manifest (tropias)
Latent (phorias)

PSEUDOSTRABISMUS
Pseudoexotropia- in hypertelorism
Pseudoesotropia- in prominent
epicanthal folds, high myopia

SECTION 4
TREATMENT OBJECTIVES

WHY WE TREAT
1- Restore Stereopsis
2- Prevent Amblyopia
3- Prevent Confusion and Diplopia
4- Appearance

WHY WE TREAT
1- Restore Stereopsis
Three dimensional vision..

WHY WE TREAT
2- Amblyopia
Amblyopia is the unilateral or bilateral decrease of
Vision caused by form vision deprivation and/or
abnormal binocular interaction for which there is
no obvious cause found by physical examination
of the eye.

WHY WE TREAT
The main types of Amblyopia are:
1. Strabismic amblyopia results from abnormal
binocular interaction where there is continued
monocular suppression of the deviating eye. It
is
Characterized by an impairment of vision which
is
present even when the eye is forced to fixate.

WHY WE TREAT
2. Anisometropic amblyopia is caused by a
difference in refractive error. It results from
abnormal binocular interaction from the
superimposition of a focused and unfocused
image
or from the superimposition of large and small
images from aniseikonia.
3. Deprivation Amblyopia is caused from form
vision deprivation of one eye.

WHY WE TREAT
3- Confusion and Diplopia
DEFINITIONS
1. Visual axis is a line that passes through the point of fixation and the fovea. The
normal visual axes intersect at the point of fixation.
2. Strabismus is a malalignment of the visual axes which, initially, results in
confusion and diplopia.
3. Confusion is the simultaneous appreciation of two superimposed but dissimilar
images caused by stimulation of corresponding points (usually foveae) by
images of different objects.
4. Diplopia is the simultaneous appreciation of two images of one object. Jt
results from a failure to maintain binocular vision.

DIPLOPIA AND
CONFUSION
Worth Four Dot Test

WHY WE TREAT
4- Appearance

APAO BEIJING 2010- PUPPET SHOW

SECTION 5
CLINICAL EXAMINATION OF STRABISMUS

EXAMINATION
1.HISTORY
A. Deviation: Age of onset
Description of deviation
Previous treatment
B. Pre and post natal factors
Growth and development
Family history of strabismus
2.GENERAL OBSERVATION.
Abnormal head posture

SQUINT EXAMINATION
3. VISUAL ACUITY
a. Without glasses and with glasses
b. Near and distant vision
c. Amblyopia testing
4.MOTOR:
a. Extra ocular movements.
b. Phorias or tropias
c. Near point of convergence and near point of accommodation.

SQUINT EXAMINATION
5. MEASUREMENT OF DEVIATION.
Distance and near
Without glasses and with glasses( if worn)
6. SENSORY TESTS
Worth 4 dot test.
Stereopsis
7. FIXATION: monocular , alternating, binocular
8. SLIT LAMP EXAMINATION.

SQUINT EXAMINATION
9 . FUNDUS EXAMINATION.
10 . CYCLOPLEGIC REFRACTION.

STRABISMUS EXAMINATION
• Corneal
Reflection Test

PSEUDOSQUINT

VISION TESTS
• In infants:
- fixation and following light
- Catford drum test
- preferential looking test
- Cardiff acuity test
- VER
- reflex responses

PEDIATRIC VISION ASSESSMENT
• In 1 to 2 yr old:
- Boeck candy test
- Worth’s ivory ball test
- coin test
- miniature toys test
- dot visual acquity test

PEDIATRIC VISION TESTS
- tumbling E test
- Landolt’s C test
- Sheridan letter test

SENSORY TESTS
• Worth’s 4 dot test
• Bielchowsky’s after image test
• Striated glasses of Bagolini
• 4 diopter prism base out test
• Synaptophore

STEREOPSIS TESTS
• Titmus stereo test
• Random dot stereogram test
• Random dot e test
• TNO test
• Lang test
• Frisby test
• 2 pencil test

TITMUS FLY TEST

TNO TEST

LANG TEST

HEAD POSTURE
• Incomitant squint
• Position of head in which the eyes are
in a position of no deviation or very
small deviation so that fusion is
possible.
• 3 components:
-Chin
-Face turn
-Head tilt

TESTS TO MEASURE DEVIATION ANGLE
• Hirschberg corneal reflex test
• Krimsky’s test
• Cover test
• Alternate cover uncover test
• Prism bar cover test
• Maddox wing test
• Maddox rod test

MOTILITY TESTS
• Ocular movements
- versions
- ductions
• Near point of convergence- RAF rule
• Near point of accomodation- RAF rule
• Fusional amplitudes- with prism bar or
synaptophore

DIPLOPIA TESTS
• Hess test
• Lees screen

AMBLYOPIA
• Unilateral or bilateral DOV due to
form deprivation &/or abnormal
binocular interaction for which there
is no ocular or visual pathway
pathology
• Most commonly due to squint, large
uncorrected refractive errors etc.
• Treatment:
- occlusion
- penalisation

Cover – Uncover test
Orthophoria, normal
No complaints,
asymptomatic
G.Vicente,MD
G.Vicente,MD

Esophoria, abnormal,
common
Only seen when eye is
covered
Often asymptomatic, no
complaints
Note OS does not move. G.Vicente,MD

Exophoria, abnormal,
common
Only seen when eye is
covered
Note OS does not move
Often asymptomatic, no
complaints. G.Vicente,MD

Alternate Cover test
Exotropia, intermittent
May be visible with or
without alternate cover
May have intermittent
diplopia, especially when
tired or sick
Mom sees misalignment
every now and then.
G.Vicente,MD

Exotropia, Constant
May be visible with or
without alternate cover
May or may not have
constant diplopia
G.Vicente,MD

with Prism
Exotropia, Constant
Use prism to quantitate
the deviation.
Change prism power
until movement is
neutralized.
Use this number to plan
surgery
How much to operate…
G.Vicente,MD

ALTERNATE COVER TEST-VIDEO

ESO DEVIATION

EXO DEVIATION

VERTICAL HYPER DEVIATION

RAPD NORMAL

CORNEAL REFLEX

DIRECT PUPILLARY LIGHT REFLEX

OCULAR DUCTIONS

ALTERNATE COVER TEST
ESOPHORIA

ALTERNATE COVER TEST
EXOPHORIA

ACCOMMODATIVE REFLEX/
NEAR REFLEX

SIXTH NERVE PARESIS MASKED

OCULAR VERSIONS

ESCRS VIENNA 2011

Section 6
Esotropia

ESOTROPIA

ESOTROPIA
Inward deviation of the eyes
Classification of Esotropia:
- Comitant or incomitant.
- Accommodative or non-accommodative

ESOTROPIA
ACCOMMODATIVE ESOTROPIA
1. Refractive
. fully accommodative
. partially accommodative
2. Non-refractive
. with convergence excess
. with accommodation weakness

ESOTROPIA
NON-ACCOMMODATIVE ESOTROPIA
. Infantile
. microtropia
. basic
. convergence excess
. convergence spasm
. divergence insufficiency
. divergence paralysis
. sensory
. consecutive
. acute-onset
. cyclic

REFRACTIVE ACCOMMODATIVE ESOTROPIA
Refractive accommodative esotropia, with a normal
AC/A ratio, is a physiological response to excessive
hypermetropia and is beyond the patient's fusional
divergence amplitude.
The deviation presents at about the age of 2.5 years, with
a range of 6 months to 7 years. The two types are:
1. Fully accommodative, which is completely eliminated by correction of the
hypermetropic refractive error
2. Partially accommodative, which is only partially eliminated by correction of
hypermetropia

MANAGEMENT
1.Refraction is performed and any significant error corrected. In
children under the age of 6 years, the full cycloplegic refraction
should be prescribed. In the fully accommodative refractive
esotrope this will control the deviation for both near and distance.
2. Bifocals may be prescribed if there is accommodative esotropia
for near. The purpose of bifocals is to allow the child to maintain
fusion at near. The ultimate prognosis for complete withdrawal of
spectacles is related to the degree of hypermetropia, the amount of
associated astigmatism and also the AC/A ratio. In some cases the
spectacles need to be worn only for close work.

3. Surgery should be considered if spectacles do not fully correct the
deviation and after every attempt has been made to treat
amblyopia. The two main surgical options are:
(a) Recession-resection on the amblyopic eye in patients with residual
amblyopia.
(b) Bilateral medial rectus recessions in patients with equal vision in
both eyes.

INFANTILE ESOTROPIA
Infantile (Congenital) Esotropia
CLINICAL FEATURES
Infantile Esotropia is defined as Esotropia
developing within the first 6 months of birth
in an
otherwise normal infant.

INFANTILE ESOTROPIA
1. Signs
(a) The angle is usually fairly large (>30) and stable.
(b) Fixation in most infants is alternating in the primary
position and crossfixating in side gaze, so that the child
uses the right eye in left gaze and the left eye in right gaze.
This pattern of crossed fixation will give the false
impression of abduction deficit with a bilateral sixth nerve
palsy. However, abduction can usually be demonstrated
by either using the doll's head manoeuvre or rotating the
child.

INFANTILE ESOTROPIA
(c) Nystagmus, if present, is usually
horizontal although it may be latent.
(d) The refractive error is usually normal for
the age of the child (about +1.50 D).
(e) Inferior oblique overactions may be
present initially or develop later.
(f) Poor potential for BSV.

INFANTILE ESOTROPIA
2. Differential diagnosis
(a) Congenital sixth nerve palsy.
(b) Sensory Esotropia due to organic eye disease.
(c) Nystagmus blockage syndrome in which
Esotropia dampens a horizontal nystagmus.
(d) Duane syndrome types I and III.
(e) Mobius syndrome.
(f) Strabismus fixus.

INFANTILE ESOTROPIA
MANAGEMENT
Initial management. Ideally, the eyes should be aligned at the very
latest by the age of 2 years. This usually means performing the
initial surgery before the age of 12 months, but only after amblyopia
has been corrected. The initial procedure is recession of both
medial recti. Any associated overactions of the inferior obliques
should also be treated. An acceptable goal is alignment of the eyes
to within 10 PD, associated with peripheral fusion and central
suppression. This small-angle residual strabismus is compatible with
a stable outcome even if bifoveal fusion is not achieved.

INFANTILE ESOTROPIA

Section 6
Exotropia

EXOTROPIA
Classification
1. Constant
. Congenital
. Sensory
. Consecutive
2. Intermittent
. divergence excess (worse for distance)
. convergence weakness (worse for near)
. basic exotropia (same for distance and near)

CONSTANT EXOTROPIA
CONGENITAL EXOTROPIA
1. Presentation is at birth, in contrast to infantile esotropia.
2. Signs
(a) Normal refraction.
(b) Large and constant angle.
(c) DVD may be present.
3. Treatment is mainly surgical.

CONSTANT EXOTROPIA
OTHER TYPES
1. Sensory Exotropia, which is the result of disruption of binocular
reflexes by acquired lesions, such as cataract or other opacities of
the media, in children over the age of 5 years or in adults. If
possible, treatment consists of correction of amblyopia followed by
surgery.
2. Consecutve exotropia: which most frequently follows previous
correction or overcorrection of an esodeviation

INTERMITTENT EXOTROPIA
Presentation is most frequent at around 2 years.
The Exotropia may be precipitated by bright light
(resulting in reflex closure of the affected eye),
day-dreaming, fatigue, ill health or visual
distraction. Occasionally, the deviation remains
constant and very rarely it may decrease.

INTERMITTENT EXOTROPIA
MANAGEMENT
1. Spectacle correction in myopic patients may, in some
cases, control the deviation.
2. Orthoptic treatment consisting of occlusion therapy,
diplopia awareness, and improvement of fusional
convergence, may also be useful in selected cases.
3. Surgery is necessary in most patients by about the age
of 5 years.

Section 7
Rare Syndromes

SYNDROMES
Duane Syndrome
Brown Syndrome

DUANE SYNDROME
The hallmark of Duane syndrome is retraction of
the globe on attempted adduction caused by co-
contraction of the medial and lateral recti. Both
eyes are affected in about 20% of cases. Some
children with Duane syndrome have associated
congenital defects; the most common is perceptive
deafness with associated speech disorder.

DUANE SYNDROME
CLASSIFICATION
1. Type I, the most common, is characterized by:
. Limited or absence of abduction.
. Normal or mildly limited adduction.
. In the primary position, straight or slightly esotropic.
2. Type II, the least common, is characterized by:
. Limited adduction.
. Normal or mildly limited abduction.
. In primary position, straight or slightly exotropic.
3. Type III, is characterized by:
. Limited adduction and abduction.
. In the primary position, straight or slightly esotropic.

DUANE SYNDROME
Other features, which may occur in each of the subgroups, are the following:
(a) On attempted adduction there is retraction of the globe and narrowing of the
palpebral fissure, produced by the co-contraction of the medial and lateral
recti of the involved eye.
(b) On attempted abduction, the palpebral fissure opens and the globe assumes
its normal position.
(c) An up-shoot or down-shoot in adduction is seen in some patients. It has been
suggested that this is a 'bridle' or 'leash' phenomenon, produced by a tight
lateral rectus muscle which slips over or under the globe and produces an
anomalous vertical movement of the eye.

DUANE SYNDROME

DUANE SYNDROME
Management
In most cases the eyes are straight in the primary position and there
is no amblyopia. Surgery is indicated if the eyes are not straight in
the primary position and the patient has to adopt an abnormal head
posture to achieve fusion.
Surgery may also be necessary for cosmetically unacceptable up-
shoots, down-shoots or severe retraction.
Amblyopia, when present, is usually the result of anisometropia and
not strabismus.

BROWN SYNDROME
CLINICAL FEATURES
1. Major signs of a right Brown syndrome are:
(a) Usually straight in the primary position.
(b) Limited right elevation in adduction and occasionally also in the
primary position.
(c) Usually normal right elevation in abduction.
(d) No or minimal superior oblique overaction.
(e) Positive forced duction test on elevating the globe in adduction.

BROWN SYNDROME

BROWN SYNDROME
2. Variable signs
(a) Downshoot in adduction.
(b) Hypotropia in primary position.
(c) Anomalous head position with
ipsilateral head tilt and chin up.

BROWN SYNDROME
CAUSES
Brown syndrome is usually congenital but occasionally may be acquired:
1. Congenital
(a) Idiopathic.
(b) Congenital click syndrome where there is impaired movement of the tendon
through the trochlea.
2. Acquired
(a) Iatrogenic damage of the trochlea or superios oblique tendon.
(b) Inflammation of the tendon which may be caused by rheumatoid arthritis,
pansinusitis and scleritis.

BROWN SYNDROME
Management
1. Congenital cases do not usually require
treatment. Indications for surgery include the
presence of a primary position hypotropia
and/or an anomalous head posture.
2. Acquired cases may benefit from steroids.

BROWN’S SYNDROME

STRABISMUS
• Treatment:
• Should be started as early as possible
• Glasses
• Surgery
• (Botox Injections)

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Strabismus squint evaluation and management

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