2016 basic motility exam

Basic Motility Examination

Alvina Pauline D. Santiago, MD Pediatric Ophthalmology & Strabismus

Basic Course Lectures in Ophthalmology

Sentro Oftalmologico Jose Rizal Philippine General Hospital 2016

Basic Strabismus Evaluation

•  Chief complaint and History

•  Vision assessment (with vision screening)

•  Gross evaluation and slit lamp examination

•  Refraction and need for cycloplegia

•  Sensory & Motor examination (Motility Examination)

•  Dilated posterior pole evaluation

Sensory Testing

•  Perform before any type of monocular occlusion •  e.g., visual acuity testing, cover tests

•  Must wear correct prescription

•  May need to correct deviation

•  Prefer to do on a second visit

Sensory Testing

•  Near stereoacuity •  Fly vectograph/ Titmus Fly Test •  Lang stereotest •  Random dot stereograms

•  Distance stereoacuity •  Mentor BVAT •  AO vectograph •  Amblyoscope

Stereoacuity tests

•  Horizontal disparity

•  Stimulate non-corresponding points

•  Image disparity measured in sec of arc

•  40-50 sec = central or bifoveal fixation

•  80-3000 sec = peripheral fusion

Titmus fly test

•  Monocular cues

•  Need polarized glasses

•  Image displacement may be detected by alternate suppressors

•  Turn book 90 degrees, should be flat

From Rosenbaum & Santiago, Clinical Strabismus Management

Lang Stereoacuity test

•  Random dot stereogram

•  No need for Polaroid lenses

•  Only for gross and low grade stereopsis

Random Dot Stereogram

•  2 plates of randomly displayed dots, one plate to each eye

•  Shape of figure displaced horizontally relative to other plate

•  No monocular cues

•  Normal may fail

Distance Stereotest

•  Mentor BVAT System

•  Very good test for assessing control in X(T)

Red-Green Distance Stereotest

Sensory Testing

•  Worth 4 dot •  near: tests peripheral fusion •  distance: tests central fusion

•  Retinal correspondence •  amblyoscope, Bagolini lenses

•  4 pd BO test: foveal suppression •  N: conjug sacc OU, slow recov in nonprism eye

Worth Dot Test

•  2 green lights

•  1 red light

•  1 white light

•  Red-green glasses

•  Usually red over right eye

•  At 1/3 m: •  W4D separated by 6 degrees

•  Tests peripheral fusion

•  At 6 m: •  1.25 degrees

•  Tests central fusion

Worth Dot Test Results

http://image.slidesharecdn.com

Amblyoscope or Haploscope

Amblyoscope

•  Measures fusional vergence amplitudes

•  Angle of deviation

•  Area of suppression

•  Retinal correspondence

•  Torsion

•  Instrument convergence

Motor Testing

•  Ocular rotations

•  Measuring the deviation

•  Anomalous head posture

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

Ocular Rotations Cardinal gaze positions

Ocular Motility Evaluation

(L) Inferior oblique dysfunction

-4 -1 From Rosenbaum & Santiago, Clinical Strabismus Management

(R) Superior oblique dysfunction

Motor Testing

•  Light reflex tests

•  Cover tests

•  Other tests

•  wear correction

•  no prisms

Motor Testing: Light Reflex Tests

•  Bruckner test

•  Hirschberg light reflex

•  Krimsky/modified Krimsky

Bruckner Test ® Ametropia ® Strabismus

Hirschberg’s Corneal Light Reflex

•  3.5 mm pupil: •  15 deg at pupil edge

•  30 deg between limbus and edge of pupil

•  45 degrees at limbus

•  Not a true linear relationship:

21 pd/mm decentration

Krimsky vs Modified Krimsky

•  in front of deviating eye (modified Krimsky)

•  underestimates true angle

•  better at near

LIGHT REFLEX, COVER TESTS (Courtesy of R. Pena, MD)

MODIFIED KRIMSKY

Motor Testing: Cover Tests

•  Primary gaze

•  Right and left gaze

•  Up and down gaze

•  Right and left head tilt

•  Oblique gazes, occasionally

•  Near: primary and down gaze

Cover Tests

•  Requirements: •  Appropriate correction

•  Know if correction has no prisms or with prisms

•  Accommodative target

•  Distance: •  6 m: 1/6 D of accommodation

•  (approximates infinity)

•  > 6 m: X(T)

The Ideal Target

•  Above threshold •  e.g. Snellen acuity 20/20

•  present 20/50 to 20/70

The Ideal Target

•  With sufficient detail and contour

•  Should sustain interest

Toys as Targets

•  One toy one look

•  With detail

•  May be coupled with a light

•  Sounds for tracking but not vision testing

The Ideal Target

•  Maximum plus, least minus correction

•  Allows minimal accommodation at 6 m

•  Accommodation exerted only 1/6 Diopter, considered zero for strabismus measurement purposes

Factors Affecting Measurement

•  Prism placement: •  plastic prisms: frontal

plane •  glass prisms: prentice

position

•  Stacking prisms

•  Splitting prisms

•  Method of testing: •  Light reflex:

•  Bruckner

•  Hirschberg

•  Krimsky/modified Krimsky

•  Different cover tests •  Cover Test

•  Alternate Cover Test

•  Patient factors: •  Accommodation and AC/A ratio

•  Axial length and globe size

•  Amblyopia and eccentric fixation

•  Refractive error and induced prisms

Cover Tests

Cover Uncover Test

•  Must be performed before alternate cover test •  Cover test: tropia

•  Uncover test: phoria

•  also for fixation preference

Alternate Prism Cover Test

•  Prisms before deviated eye •  primary vs. secondary deviation

•  Unless strabismic eye is preferred for fixation

•  Evaluates total deviation: manifest (tropic) and latent (phoric)

ALTERNATE PRISM & COVER TEST

Gold standard for measuring deviation

Simultaneous Prism Cover Test

•  Tropia under binocular conditions

•  Monofixation syndrome •  Estimate angle of deviation

•  Present prism and cover simultaneously

•  Absence of movement in tropic eye means correcting prisms are accurate

SIMULTANEOUS PRISM & COVER TEST

Used for monofixation

Prism Under Cover Test

•  For Dissociated Vertical Deviation

•  Evaluate one eye at a time

•  Prism and cover presented to the same eye

•  Separate true hypertropia by using BU prism neutralization in other eye

Dissociated Vertical Deviation

Courtesy of N. Paderna, MD

PRISM UNDER COVER TEST

Used for DISSOCIATED VERTICAL DEVIATION (DVD)

Techniques in Finding Strabismus

•  Bruckner test

•  Spielmann translucent occluder

Other Tests

•  Red glass test

•  Maddox rod •  horizontal, vertical

•  torsional

•  Parks 3-step test for isolated cyclovertical muscle palsy •  3rd step is Bielschowsky maneuver

(L) Superior oblique palsy

Parks 3-step Test Left Hypertropia

•  I. Of 8 cyclovertical muscles: 4 •  LSO, LIR, RSR, RIO

•  II. Of 4 cyclovertical muscles: 2 •  increase on R gaze: LSO,

•  III. Of 2 cyclovertical muscles: 1 •  increase of L tilt: LSO

Torsion Evaluation

•  Funduscopy

•  Fundus photography

•  Blind spot mapping

•  Red-Green Hess/Lee Screen

•  Double Maddox Rods

•  Oblique (& Vertical) muscle dysfunction

Normal Optic Nerve Head-Fovea Angle Relationship

Direct Ophthalmoscope View: Fundus Torsion

Excyclorotation Incyclorotation

Indirect Ophthalmoscope View: Fundus Torsion

Excyclorotation Incyclorotation

Inferior Oblique Overaction

PREOP POSTOP

Torsion Test: Double Maddox

Tests of Muscle Function

•  Forced duction test

•  Force generation test

•  Saccadic velocity analysis

•  EMG

•  Dynamic MRI

Indications

•  Incomitant deviation

•  Limited ocular rotation

•  Distinguish between restriction and paresis/palsy

•  Distinguish between paresis and palsy

Passive Forced Duction

•  Some indications: •  Trauma

•  Endocrine

•  Postoperative restriction of motility

•  Longstanding deviation with secondary contracture

•  Congenital restrictions

•  Brown

•  Duane

•  Transposition procedures

•  Orbital diseases

•  Tumors

•  Inflammation

Advantages

•  Help in deciding between treatment options

•  Monitor improvement of paretic mm

Tests of Muscle Function

•  Paresis vs. restriction •  Forced duction test

•  Force generation test

•  Saccadic velocity analysis

•  Differential intraocular pressure

EMG: Electromyography

•  Limitations: •  may record activity even if muscle still

paretic

•  response suppressed by GA

•  still used in some cases of Duane syndrome and Botulinum injection

•  Children > 7 yrs, adults

•  Topical anesthetic

•  Cover one eye: ensures fixation

•  Look as far as possible in the direction of limited ocular rotation

•  Provide fixation target

•  Watch out for “falling off” of eye

“Can the forceps rotate the eye further than the patient can using maximal innervation in that gaze field?”

•  Grasp limbus opposite the side of limited gaze •  Tenon’s and conj fused in one layer •  limits stretching/tearing of conj •  provides firm grasp

•  Follow natural arc of globe

•  For rectus muscles •  Slight proptosis •  No retroplacement

•  Vertical rectus: 23 deg abduction

•  Results: •  cannot move globe further: restriction •  can move globe further: paresis

® For Oblique Muscles: ® Retroplace globe ® Follow oblique muscle path

® Guyton’s Oblique Traction Test ® “Stress Test” for obliques ® Retroplace globe ® Torsional movement

Oblique traction testing

Intraoperative Forced Duction Testing

•  Perform routinely to feel “normal”

•  Perform esp after resections •  may be ortho in primary •  overcorrection in certain gazes

•  Perform after transpositions

•  Intraoperative adjustable suture

•  Perform after removing suspected restrictions

Forced Duction Results

•  Absolute restriction •  Graves, Brown

•  Uniform restriction •  Scar tissue, muscle contracture

•  Leash phenomenon •  Scar tissue, long standing contracture

•  Duane syndrome

Pitfalls: Forced Duction

•  Patient apprehension

•  Errors in technique •  “Falling off” •  Failure to proptose or retropulse globe

•  Succinylcholine (Anectine)

•  Posterior restrictions

•  Co-contractions

•  Co-existing paresis and restriction

Active Force Generation

•  Apply a counteracting force

•  Using the same grasp on limbus

•  Countertraction to feel resistance

•  WOF: corneal abrasion, conj heme

Active Force Generation

•  Differential IOP

•  Paresis vs. palsy

•  Combined paresis and restriction

Results: Force Generation

•  No force generated: Palsy

•  Weak force generated: Paresis

•  Strong force generated: Restriction

•  Common pitfall: mild paresis

•  Correlate with saccadic velocity analysis

FDT, FGT, Diagnosis

DIAGNOSIS FDT FGT

Mech restriction restricted normal

Muscle palsy free absent

Paresis & restriction restricted weak

Saccadic Velocity Analysis

•  Study eye movement velocity •  muscle activity

•  return of muscle function

•  EOG : problem when testing vertical saccades

•  Infrared

•  Scleral search coil

Office Saccadic Velocity

•  Look at 2 separate targets

•  At least 20 deg movt sufficient

•  Compare •  briskness of agonist and antagonist •  with fellow eye

•  Bring the eye where muscle has •  maximum function •  full unrestricted motion

Pitfalls: Saccadic Velocity

•  Errors in technique •  failure to bring eye

where muscle is still functioning

•  Pharmacologic

•  Fatigue

•  Time of day

Clinical Applications: SV

•  Paralytic Strabismus

•  Restrictive

•  Lost or slipped muscles

•  Neurologic Disorders •  MG: normal then weakens; use with Tensilon •  PEO: general slowing •  INO: slowed adduction; normal abduction

Slowed Saccadic Velocities

•  LR palsy abduction

•  SO palsy downgaze

•  Moebius horizontal

•  Myasthenia normal then slows

•  Slipped/Lost reduced 20-50%

Magnetic Resonance Imaging

•  Cross-sectional area

•  Applications: •  EOM palsy

•  EOM heterotopy

•  Severed/extirpated muscles

•  Entrapment

•  Mass

Normal coronal section

Laser vision ;-)

No more than a pinhole effect!

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