2014 asmph strabismus & amblyopia
DESCRIPTION
Strabismus & Amblyopia Lecture to Yr Level 7 ASMPH December 10, 2014TRANSCRIPT
Revised Dec 2014 ASMPH Y7
Strabismus & Amblyopia
Alvina Pauline D. Santiago, MD Pediatric Ophthalmology & Strabismus
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Anatomy of Extraocular Muscles
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EOM Mechanisms
! Actions of muscles ! Ductions & Versions ! Vergence movements: convergence,
divergence ! Hering’s & Sherrington’s laws
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Orbital apex
Medial rectus
www.wikipedia.org
adduction
Lateral rectus
www.wikipedia.org
abduction
Inferior rectus
! depressor ! adducts ! excyclotorsion
www.wikipedia.org
Superior rectus
! elevates ! adducts ! incyclotorts
www.wikipedia.org
Superior oblique
! incyclotorts ! depresses ! abducts
www.wikipedia.org
Inferior oblique
! excyclotorts ! elevates ! abducts
www.wikipedia.org
08 January 2010 ASMPH Y7
EOM Movements
! Duction: rotation from one eye ! Versions: movement of both eyes from
primary position (straight) to secondary position
! Vergence: simultaneous ocular movements ! convergence: nucleus of Perlia (midbrain) ! divergence: midbrain near acoustic nerve nucleus
Ocular Motility
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Laws of Ocular Motility
! Hering’s law of equal innervation ! explains conjugate eye movements ! Yoke muscles receive equal innervation
! Sherrington’s law of reciprocal innervation ! concerned with coordination of muscle pairs of one eye ! when agonist contracts, there is inhibition of its direct antagonist
Yoke muscles: Hering’s Law
RLR LMR
RMR LLR
RSR
LIO
RIR LSO
RIO LSR
RSO LIR
Antagonist Muscles: Sherrington’s Law
RLR (-) RMR
RSR
(-) RIR
RIR (-) RSR
RIO
(-) RSO
RMR
(-) RLR
RSO
(-) RIO
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Vision Assessment
Preverbal Age Group
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Visual acuity testing
• Evaluating fixation and preference • Using Allen cards or other preverbal test
charts
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Visual milestones
• Birth Bright lights • 7 days vestibulo-ocular reflex • 3 mos transient FF • 6 mos FF even for distance • 2-3 y 20/30 • 5-7 y 20/20
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Vision Assessment
• Fixation pattern • 3 mos: transient fix and follow • 6 mos: fix and follow
– “CSM” nomenclature – cover one eye – start distance fixation
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Fixation preference
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Fixation Preference
Son: Left Left Left None
TEXT TEXT TEXT TEXT
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Profound Amblyopia
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Fixation Preference & Visual Acuity
• Central, steady, maintained CSM 20/20-20/30
• CS, maintained briefly 20/40-20/60 • CS, not maintained (NM)20/70-20/80 • C, NS, NM 20/100-20/200 • Not C, Eccentric </= 20/300
08 January 2010 ASMPH Y7
Vision Assessment
Non/Pre Verbal
OKN Drum FPL OKN Flag Teller
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Visual Acuity Testing
• Test Charts – HOTV / HOTEX – “E” Game – Landolt C – Picture Charts
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Vision Assessment
Picture Charts HOTV SNELLEN
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Strabismus Testing Tests of Ocular Alignment
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Motor Testing
• Ocular rotations • Measuring the deviation • Anomalous head posture
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Ocular Rotations
• Duction: monocular • Version: binocular • Hering’s law • Sherrington’s law • Alert to pattern deviations: e.g., A, V • Grading scheme:
– e.g., inferior oblique & superior oblique
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Ocular Motility Evaluation
RLR
LMR
RMR
LLR
RSR
LIO
RIR
LSO
RIO
LSR
RSO
LIR
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Ocular Rotations: Yoke muscles Cardinal gaze positions
RLR
LMR
RMR
LLR
RSR
LIO
RIR
LSO
RIO
LSR
RSO
LIR
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(L) Inferior oblique dysfunction
+4 +1
-4 -1
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(R) Superior oblique dysfunction
+4 +1
-4 -1
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Ocular misalignment
• Hirschberg’s light reflex test • Bruckner’s red orange reflex test • Alternate prism cover test
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Hirschberg’s Corneal Reflex
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Hirschberg’s Corneal Reflex
Mom: straight Son: RET RET RXT PseudoET
TEXT TEXT TEXT TEXT
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Pseudostrabismus
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Head posture, Anomalous?
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Anomalous head posture
• Measure in non preferred head posture
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Motor Testing
• Light reflex tests • Cover tests • Other tests
– wear correction – no prisms
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Motor Testing: Light Reflex Tests
• Bruckner test • Hirschberg light reflex • Krimsky/modified Krimsky
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Bruckner Test
® Ametropia ® strabismus
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Hirschberg’s Light Reflex
• 3.5 mm pupil: – 15 degrees at pupil
edge – 30 degrees between
limbus and edge of pupil
– 45 degrees at limbus
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Krimsky vs Modified Krimsky
– in front of deviating eye (modified Krimsky)
– underestimates true angle
– better at near
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Motor Testing: Cover Tests
• Primary gaze • Right and left gaze • Up and down gaze • Right and left head tilt
• Near: primary and down gaze
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Cover Tests
• Requirements: – appropriate correction – no prisms vs. prisms – accommodative target – distance:
• 6 m: 1/8 D of accommodation • > 6 m: X(T)
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Techniques in Finding Strabismus • Bruckner test • Spielmann
translucent occluder
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(L) Superior oblique palsy
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Direct Ophthalmoscope View: Fundus Torsion
Excyclorotation Incyclorotation
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Paralytic Exotropia:III nerve palsy
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Inferior oblique dysfunction
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Bruckner (Red Orange Reflex)
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Amblyopia
Pediatric Eye Disease Investigator Group (PEDIG)
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Thank You!