STRABISMIC STRABISMUS OR IS IT NEUROLOGICAL / SINISTER

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STRABISMUS IS IT STRABISMIC ?.
NEUROLOGICAL?OR BOTH?

• LIONEL KOWAL
• DIRECTOR, OCULAR MOTILITY CLINIC, RVEEH
• SENIOR CLINICAL FELLOW, DEPT OPHTHALMOLOGY,
  UNIVERSITY OF MELBOURNE
• FIRST VICE PRESIDENT, INTERNATIONAL
  STRABISMOLOGICAL ASSOCIATION, 2002-2010

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OVERVIEW.

• OF THE CAUSES, ASSOCIATIONS AND TYPES OF
  STRABISMUS
• IDENTIFYING SOME COMMON / UNDER- RECOGNISED
  ASSOCIATIONS

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STRABISMUS

• Any ocular misalignment
• INCLUDES
• Abnormalities of development of acuity
• Abnormalities of development of binocularity
• The variants of congenital nystagmus

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CHILDHOOD STRABISMUS

• 1. Derive largely from refractive disorders
• 2. Pure neurological
• 3. Derive largely from abnormal early visual
  devpt
• 4. Special types

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STRABISMUS END RESULT OF A COMPLEX JIGSAW PUZZLE

• Abnormalities in one / more of
• Sensory development
• Refraction
• Orbital anatomy
• EOM anatomy / physiology
• Cortical / supranuclear
• Accommodation / convergence
• either cause or are caused by strabismus

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COMPLEX JIGSAW PUZZLEAbnormal Sensory
development

• Amblyopia
• Suppression
• Abnormal retinal correspondence

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COMPLEX JIGSAW PUZZLEAbnormal Refraction

• Hyperopia or plus error
• Causes esotropia
• Any asymmetric refractive error
• Causes amblyopia, esotropia if
• so-called long sighted - NOT the mirror image
  of short sighted. The patient can see clearly by
  generating focusing effort accommodation

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COMPLEX JIGSAW PUZZLEAbnormal orbital anatomy1

• Orbital pulley heterotopy
• Changes muscle actions
• Globe size distorting muscle cone
• Causes pseudo- 6th
• Shallow / deep orbit
• Shallow more prone to exotropia

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COMPLEX JIGSAW PUZZLEAbnormal orbital anatomy 2

• Intorted / extorted orbit
• More prone to alphabet patterns
• Plagiocephaly
• More prone to oblique dysfunction

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COMPLEX JIGSAW PUZZLEAbnormal EOM anatomy /
physiology

• Oblique muscle dysfunction
• Abnormal elevation / depression in AB- or AD-
  duction
• Globe torsion
• Abnormal innervation Duane's, CFEOM
• Strange incomitant strabismus

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COMPLEX JIGSAW PUZZLEAbnormal cortical /
supranuclear substrate 1

• ? motor fusion
• oculomotor shock absorber / glue that tries
  to keep eyes straight
• ? sensory fusion
• stereopsis
• Abnormal binocular columns

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COMPLEX JIGSAW PUZZLEAbnormal cortical /
supranuclear substrate 2

• Abnormal interneurons
• Latent Manifest Latent Nystagmus LMLN
  Fixation Maldevelopment N
• Just about any cause / association of devptl
  delay
• Chiari
• PVL

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COMPLEX JIGSAW PUZZLEAbnormal Accom - Conv
relationship

• Accom ? too much convergence
• Conv ? too much accommodation
• too little is rarely a problem

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TYPES OF STRABISMUS

• 1. Derives from refractive disorders
• 2. Pure neurological
• 3. Derives from abn early visual devpt
• 4. Special types

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NORMAL ACCOMMODATION
Accommodation and convergence Focus and Aim
are very tightly linked
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ACCOMMODATIVE / OPTOMETRIC ESOTROPIA

• 4 Abn degree of accommodation required to see
  clearly
• Abn amount of accomm convergence is generated
• competes against motor fusion oculomotor shock
  absorber

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WHAT DOES 4 MEAN?

• For distance, generates same accommodation that
  perfect person generates when looking 1/4 m
  away.
• For distance fixation, eyes will tend to aim _at_ a
  point 25cm away
• When looking _at_ an object 25cm away, eyes will aim
  _at_ a point 12 cm away

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ACCOMMODATIVE / OPTOMETRIC ESOTROPIA

• Exactly the same can happen with low and
  abnormal accomm - convergence relationship
• Many of these ? bifocals
• many synonyms - convergence Xs, high AC/A ratio

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Developing an esotropia

• Prolonged accommodation ? tendency to
  inappropriate convergence and increased tone in
  medial recti
• Increased tone will eventually exceed motor
  fusional reserve and ? esotropia!
• Initially reversible with glasses
• Eventually the medial rectus shortens so much
  that only botox or surgery will work
• Glasses still required to prevent recurrence
  and, when older, for clear vision

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Accommodative esotropia

• Usually 2-5 yrs old
• Usually high thick magnifying lenses
• Sometimes low / normal with abnormal relation
  b/w accomm and convergence
• Background of normal visual devpt in first 6mo of
  life

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Developing an esotropia

• Happens more readily if motor fusion is
  impaired
• chromosomal defect / devptl delay
• Amblyopia
• Orbital anomaly
• LMLN
• younger, lower

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Breakdown of pre- existing phoria

• Only acceptable as a presumptive label if
• Wears thick magnifying lenses
• amblyopia
• Accomm disturbed e.g. Ditropan

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TYPES OF STRABISMUS

• 1. Derives from refractive disorders
• 2. Pure neurological
• 3. Derives from abn early visual devpt
• 4. Special types

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Pure neurological strabismus

• True cong sup obl palsy
• 6th
• CFEOM hypoplasia sup div 3rd KIF mutation
• ..have 2ary effects that are dependent on age of
  onset and associated factors such as refraction

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R SOP HEAD TILT TO LEFT
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R IO OA
R SO UA
TIGHT RSR RIR UA
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True sup obl palsy
LSO OK RSO ?absent
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REAL CONG R SOP CONG ET FIXING WITH PARETIC
R EYE
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R SO atrophic
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Fake SOPConditions that simulate SOPFalse ve
diagnostic rate ?50

• Abnormal cyclovertical anatomy
• Craniofacial anomalies
• Posteroplaced trochlea Bagolini
• Fink 20 of SO and IO have gt 30 degrees
  asymmetry in course
• Demer orbital pulley displacements
• Abnormal physiology
• Brodskys wild pitch

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TYPES OF STRABISMUS

• 1. Derives from refractive disorders
• 2. Pure neurological
• 3. Derives from abnormal early visual development
• 4. Special types

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1. Abnormal symmetric acuity devpt ? Congenital
Nystagmus CN

• Bilateral bad refractive error
• Albinism optic n dysplasia, foveal hypoplasia
• Bil optic n hypoplasia
• Bil cataracts
• CN degrades vision further
• aka Idiopathic Infantile N, Cong motor N, Cong
  Sensory N,

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Congenital Nystagmus CN

• Pendular / jerk
• Greater on lateral gaze
• UNIQUE CONVERGENCE NULL
• Face turns
• Pathognomonic waveform

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CN face turn null convergence null
Null zone on R gaze drives face turn / tilt to
L N to L when L of null N to R when R of null
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Convergence null unique to CN
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Abnormal binocularity devpt ? Latent Manifest
Latent N

• Caused by
• Any strabismus
• Asymmetric refraction
• Monocular vision reducing pathology - cataract,
  optic n hypo,.
• aka Fixation Maldevelopment N

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Abnormal binocularity devpt ? Latent Manifest
Latent N

• Jerk
• Greater on ABduction
• UNIQUE Fast phase to fixing eye
• Face turns
• RF ? R face turn, LF ? L face turn
• Head tilts RF ? R tilt, LF ? L tilt

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LMLN

• VIDEO OF POST OP LMLN NOW PURE LN

Esophoria after Exotropia surgery N to fixing eye
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LMLN N ? fixing eye
Fast phase to fixing eye
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LMLN

• COMMONLY ? CONGENITAL ESOTROPIA but can cause /
  be associated with other strabismus
• Also CAUSES DISSOCIATED H V DEVIATIONS

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CONGENITAL ESOTROPIA
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ASSOCIATIONS OF LMLN Congenital ET

• Downs 30
• Severe neonatal course IVH /HC
• near 100
• PVL

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VERTICALS IN CONG STRAB DVD Dissociated
Vertical Deviation

• Common pattern
• Right fixation L?
• L fixation R ?
• Contralateral DVD is the end result of braking
  the torsional component of LMLN in the fixing eye
  to try and improve acuity

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VERTICALS IN CET DVD
RE fixing LE ?
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CONGENITAL STRABISMUS

• Head turns / face tilts are common
• Caused by attempts to minimise blur effect of the
  LMLN

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Alternating Face Turn

• L Fixation L Face Turn
• R Fixation R Face Turn
• Ciancias syndrome preference for fixation in
  adduction because recruiting medial rectus
  brakes horizontal component of LMLN ? improved
  vision

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Special caseHead tilt to fixing eye

• LF drives HT to L
• RF no HT
• Caused by Torsional LMLN

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LF drives HT to LTorsional LMLN

• LMLN is the cong nystag seen with disorders of
  binocular development
• ?always Seen in cong ET
• Fixation Maldevelopment N.
• Usually has H component, sometimes T as well
• Fine torsional N on slit lamp
• N degrades vision - vision improves when N
  blocked

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Special caseAlternating Head Tilt

• LF drives L tilt
• RF drives R tilt
• Ciancias syndrome

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RecapAbnormal binocularity devpt ? Latent
Manifest Latent N

• Features of this type of strab recognised by the
  accompaniments.
• LMLN, one/ more of
• Head tilt / face turn to fixing eye
• DVDs
• Large angle esotropia

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Ophthalmic PVL

• Optic n hypoplasia uni-/bi-
• Cognitive visual problems - normal acuity
• Reduced acuity
• LMLN
• CN

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THINGS THAT LOOK LIKE STRABISMIC STRABISMUS

• CHIARI later onset
• deterioration of old latent strabismus
  there always has to be a credible background /
  predisposition. And a reason for breakdown

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THINGS THAT LOOK LIKE STRABISMIC STRABISMUS

• Autoimmune neuropathies
• Myesthenia

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Strabismus syndromes

• Duanes
• Browns

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Browns
Tight superior oblique tendon
Restricted elevation in aDuction
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DuanesRetraction on adduction
Retraction R on L gaze Restricted aDduction
R Restricted aBduction L
Co-firing Lateral rectus on aDuction
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Duanes
Retraction L on R gaze Restricted aDduction L
Co-firing lateral rectus on aDuction
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THANK YOU