Transcript STRABISMIC STRABISMUS OR IS IT NEUROLOGICAL / SINISTER

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
OVERVIEW….
OF THE CAUSES, ASSOCIATIONS
AND TYPES OF STRABISMUS
IDENTIFYING SOME COMMON /
UNDER- RECOGNISED
ASSOCIATIONS
STRABISMUS
Any ocular misalignment
INCLUDES:
Abnormalities of development of acuity
 Abnormalities of development of binocularity
 The variants of congenital nystagmus
CHILDHOOD STRABISMUS
1. Derive largely from refractive
disorders
2. Pure neurological
3. Derive largely from abnormal
early visual devpt
4. Special types
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
COMPLEX JIGSAW PUZZLE
Abnormal Sensory development
Amblyopia
Suppression
Abnormal retinal
correspondence
COMPLEX JIGSAW PUZZLE
Abnormal 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
COMPLEX JIGSAW PUZZLE
Abnormal orbital anatomy1
Orbital pulley heterotopy
Changes muscle actions
Globe size distorting muscle cone
Causes pseudo- 6th
Shallow / deep orbit
Shallow: more prone to exotropia
COMPLEX JIGSAW PUZZLE
Abnormal orbital anatomy 2
Intorted / extorted orbit
More prone to alphabet patterns
Plagiocephaly
More prone to oblique dysfunction
COMPLEX JIGSAW PUZZLE
Abnormal EOM anatomy /
physiology
Oblique muscle dysfunction
Abnormal elevation / depression in AB- or
AD- duction
Globe torsion
Abnormal innervation [Duane's,
CFEOM]
Strange incomitant strabismus
COMPLEX JIGSAW PUZZLE
Abnormal cortical /
supranuclear substrate 1
 motor fusion
oculomotor ‘shock absorber’ / ‘glue’ that
tries to keep eyes straight
 sensory fusion
stereopsis
Abnormal binocular columns
COMPLEX JIGSAW PUZZLE
Abnormal cortical /
supranuclear substrate 2
Abnormal interneurons
Latent Manifest Latent Nystagmus =
LMLN = Fixation Maldevelopment N
Just about any cause / association of
devptl delay
Chiari
PVL
COMPLEX JIGSAW PUZZLE
Abnormal Accom - Conv
relationship
Accom  too much
convergence
Conv  too much
accommodation
*too little is rarely a problem
TYPES OF STRABISMUS
1. Derives from
refractive disorders
2. Pure neurological
3. Derives from abn early visual
devpt
4. Special types
NORMAL
ACCOMMODATION
Accommodation and convergence
= Focus and Aim
are very tightly linked
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]
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 @ a
point 25cm away
 When looking @ an object 25cm away, eyes
will aim @ a point 12 cm away
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
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]
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
Developing an esotropia…
Happens more readily * if motor
fusion is impaired:
chromosomal defect / devptl delay
Amblyopia
Orbital anomaly
LMLN
* younger, lower +
‘Breakdown of preexisting phoria…’
Only acceptable as a presumptive
label if:
Wears thick magnifying lenses
± amblyopia
Accomm disturbed e.g. Ditropan
TYPES OF STRABISMUS
1. Derives from refractive disorders
2. Pure neurological
3. Derives from abn early visual devpt
4. Special types
‘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
R SOP
HEAD TILT
TO LEFT
R IO OA
R SO UA
TIGHT RSR
RIR ‘UA’
True sup obl palsy
LSO OK
RSO ?absent
REAL
CONG R
SOP
& CONG
ET FIXING
WITH
PARETIC R
EYE
R SO atrophic
Fake SOP
Conditions that simulate SOP
False +ve diagnostic rate ?50%
 Abnormal cyclovertical anatomy
Craniofacial anomalies
 Posteroplaced trochlea [Bagolini]
Fink : 20% of SO and IO have > 30 degrees
asymmetry in course
Demer: orbital pulley displacements
Abnormal physiology
Brodsky’s wild pitch
TYPES OF STRABISMUS
1. Derives from refractive
disorders
2. Pure neurological
3. Derives from
abnormal early visual
development
4. Special types
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,…
‘Congenital Nystagmus’ = CN
Pendular / jerk
Greater on lateral gaze
UNIQUE : CONVERGENCE NULL
Face turns
Pathognomonic waveform
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
Convergence null : unique to
CN
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
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
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
LMLN
VIDEO OF POST OP LMLN; NOW
‘PURE’ LN
Esophoria after Exotropia surgery
N to fixing eye
LMLN :
N  fixing eye
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Fast phase to fixing eye
LMLN
COMMONLY  CONGENITAL
ESOTROPIA but can cause / be
associated with other strabismus
Also CAUSES DISSOCIATED H & V
DEVIATIONS
CONGENITAL ESOTROPIA
ASSOCIATIONS OF LMLN
& Congenital ET
Down’s 30%
Severe neonatal course IVH /HC
near 100%
PVL
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
VERTICALS IN CET : DVD
RE fixing
LE 
CONGENITAL
STRABISMUS
Head turns / face tilts are
common
Caused by attempts to
minimise blur effect of the
LMLN
Alternating Face Turn
L Fixation : L Face Turn
R Fixation : R Face Turn
 Ciancia’s syndrome: preference for
fixation in adduction because
recruiting medial rectus ‘brakes’
horizontal component of LMLN 
improved vision
Special case:
Head tilt to fixing eye
LF drives HT to L
RF : no HT
Caused by Torsional
LMLN
LF drives HT to L
Torsional 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
Special case:
Alternating Head Tilt
LF drives L tilt
RF drives R tilt
= Ciancia’s syndrome
Recap…Abnormal 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
‘Ophthalmic’ PVL
Optic n hypoplasia uni-/biCognitive visual problems normal acuity
Reduced acuity
LMLN
CN
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
THINGS THAT LOOK LIKE
‘STRABISMIC’ STRABISMUS
Autoimmune neuropathies
Myesthenia
Strabismus syndromes
Duane’s
Brown’s
Brown’s
Tight superior
oblique tendon
Restricted elevation in aDuction
Duane’s
Retraction on adduction
Retraction R on L gaze
Restricted aDduction R
Restricted aBduction L
Co-firing Lateral rectus on aDuction
Duane’s
Retraction L on R gaze
Restricted aDduction L
Co-firing lateral rectus on aDuction
THANK YOU