squint examination & management- simplified !!

CONCOMITANT SQUINT EXAMINATION & MANAGEMENT

Dr. NITISH NARANG

MOTOR SYSTEM EXAMINATION• VISUAL ACUITY• HEAD POSTURE• INTER PUPILLARY DIAMETER• OCULAR DEVIATION • LIMITATION OF MOVEMENT / EXTENT OF VERSION• FUSIONAL VERGENCE

VISUAL ACUITY

• INFANTS – OCCLUSION

OPTOKINETIC NYSTAGMUS

FORCED CHOICE PREFERENTIAL

LOOKING TEST

VISUALLY EVOKED POTENTIAL• PRE SCHOOL - ALLENS CARDS

SHERIDEN GARDINER TEST• SCHOOL GOING - VISUOSCOPE

HEAD POSTURE• CHIN POSITION• FACE TURN• HEAD TILT CAUSES INCOMITANT SQUINT A OR V CONCOMITANT SQUINT NYSTAGMUS REFACTIVE CAUSES ONE EYED PERSON HOMONYMOUS HEMIANOPIA CONGENITAL SUP OBLIQUE PALSY

INTERPUPILLARY DISTANCE• ORDINARY MILLIMETER SCALE• PULZONE HARDY RULE• SYNOPTOPHORE

PSEUDOSTRABISMUS

• PSEUDOESOTROPIA

TELECANTHUS

EPICANTHUS

EURYBLEPHARON

• VERTICAL SQUINT

PTOSIS

LIDRETRACTION

• PSEUDOEXOTROPIA

HYPERTELORISM

CANTHOPLASTY

ANGLE KAPPA• VISUAL AXIS - FOVEA TO TARGET• OPTICAL AXIS - CENTRE OF PUPIL• NORMAL - 5°EXOTROPIA• HIGHER - PSEUDOEXOTROPIA-

HYPERMETROPIA• NEGATIVE - PSEUDOESOTROPIA-

MYOPES

OCULAR DEVAIATION *OBJECTIVE TESTS OF DEVIATION * COVER TEST UNCOVER TEST COVER UNCOVER TEST *PRISM BAR COVER TEST * SYNOPTOPHORE *CORNEAL REFLECTION TESTS HIRSCHBERG TEST KRIMSKY TEST

*SUBJECTIVE TESTS OF DEVIATION DIPLOPIA TEST HESS LEES SCREEN TEST *MEASUREMENT OF CYCLODEVIATION

COVER - & UNCOVER TESTPREREQUISITES• FIXATION TARGET SIZE- 6/9 SNELLENS• FIXATION DISTANCE - 33CM & 6M• SPIELMANNS TRANSLUCENT OCCLUDER

INTERPRETATION• COVER TEST - HETEROTROPIA• UNCOVER TEST - HETEROPHORIA SPEED OF RECOVERY DOMINANT EYE VISUAL ACUITY PSEUDOPTOSIS• COVER UNCOVER TEST - TRUE MANIFEST LATENT SQUINT DEVIATION DOMINANT EYE AMBLYOPIA

PRISM BAR COVER TEST• APEX OF PRISM SHOULD POINT TOWARDS DEVIATION• LARGE DEVIATIONS - 30-40Δ FOR ONE EYE ADDITIONAL

PRISM TO OTHER EYE• PLASTIC PRISM – FRONTAL POSITION• GLASS PRISM – PRENTICE POSITION• RELAX DYNAMIC FACTORS –

ACCOMMODATION :REFRACTIVE CORRECTION

FUSION :OCCLUSION

EFFECT OF GLASSES• HIGH PLUS – LESS DEVIATION • HIGH MINUS – MORE DEVIATION• MD/AD = 1- (0.025×D)

DIFFERENT ASPECTS OF MEASUREMENT• DISTANT & NEAR FIXATION - BASIC, EXCESS OR

INSUFFICIENCY• WITH & WITHOUT GLASSES – ACCOMMODATIVE

ELEMENT• CARDINAL POSITIONS OF GAZE – INCOMITANCE• UPGAZE 25 DOWN GAZE 35 – A V PATTERN• EYE FIXATING ALTERNATIVELY – PRIMARY OR

SECONDARY DEVIATION• SUBJECTIVE & OBJECTIVE METHOD – RETINAL

CORRESPONDENCE• AFTER PROLONGED COVER – TRUE / SIMULATED

DIVERGENCE EXCESS, FULLY DISSOCIATED DEVIATION

SYNOPTOPHORE

• ORTHOPTIC INSTRUMENT WITH HAPLOSCOPIC PRINCIPLE• INTERPUPILLARY DISTANCE• TORSION• ACCOMMODATIVE CONVERGENCE

RELATIONSHIP• ORTHOPTIC EXERCISES• SYNOPTISCOPE CUPRAX MAJOR• SYNOPTISCOPE OCULUS

HIRSCHBERG TEST• FIRST CATOPTRIC IMAGE OF PURKINJE SANSON• NOT EXACTLY CENTERED; SYMMETRICAL• 1MM SHIFT = 5°DEVIATION• LIMBUS = 30° = 60Δ

KRMSKYS TEST• PRISM REFLEX TEST• PRISM PLACED ON FIXATING EYE , NEUTRALISATION DONE BY

OBSERVING CORNEAL REFLEX IN DEVIATING EYE

SUBJECTIVE TESTS • DIPLOPIA PRINCIPLE – 1 PHYSICAL LOCATION

PERCEIVED AS 2 PERCEPTUAL LOCALISATIONS

RED GREEN GOGGLES

MADOX TANGENT SCALE• HAPLOSCOPIC PRINCIPLE – 2 PHYSICAL LOCATIONS

USED TO HAVE 1 PERCEPTUAL LOCALISATION

SYNOPTOPHORE

HESS/LEES SCREEN

RED – GREEN GLASS TESTING

• ESO – UNCROSSED – HOMONYMOUS• EXO – CROSSED – HETERONYMOUS • ILLUMINATED SLIT TARGET • 33CM & 6 M • 9 DIAGNOSTIC GAZE POSITIONS• INCOMITANT; DIAGNOSIS & FOLLOW UP

HESS / LEES SCREEN• GRID PATTERN EACH SQUARE = 5° EXCURSION FOR

FIXATING EYE• INNER SQUARE TESTS 15° EYE MOVEMENT FROM

PRIMARY POSITION• OUTER SQUARE TESTS 3O° EXCURSION FOR FIXING

EYE• HESS – RED GREEN GLASSES• LEES – MIRROR SEPTUM• POLAROID DISSOCIATION , LANCESTER RED GREEN TEST WITH 2 FOSTER

TORCHES WITH FILTERS

CYCLODEVIATION MEASUREMENT• DOUBLE MADDOX ROD TEST• SYNOPTOPHORE• INDIRECT OPHTHALMOSCOPY & FUNDUS EVALUATION

LIMITATION OF MOVEMENTS• LIMBUS TEST OF MOTILITY OF KESTENBAUM• GRADING OF EOM

SCALE OF 7 OR 9• GRADING OBLIQUE OVERACTION

1= UPTO 15 ANGLE WITH HORIZONTAL

2 = UPTO 30

3 = UPTO 60

4 = UPTO 90

MEASUREMENT OF VERGENCE

VERGENCE 6M : Δ 33CM:Δ

CONVERGENCE 14-20 35-40

DIVERGENCE 5-8 15-20

VERTICAL VERGENCE 2-4 2-4

INCYCLOVERGENCE 10-12° 10-12°

EXCYCLOVERGENCE 10-12° 10-12°

• NEAR POINT OF CONVERGENCE – PRINCES RULE NEAR POINT RULER ROYAL AF BINOCULAR GUAGE LIVING STONE GUAGE• CONVERGENCE SUSTENANCE• MEASUREMENT WITH PRISM

SENSORY SYSTEM EXAMINATION

• BINOCULARITY& DIPLOPIA RED GREEN GOGGLES BAGOLINI’S GLASSES MADDOX ROD DARK RED FILTER WORTH FOUR DOT TEST • CORRESPONDENCE• SUPPRESSION- BAGOLINI’S GLASSES WORTH FOUR DOT TEST SYNOPTOPHORE AFTER IMAGE TESTING• AMBLYOPIA• STEREOPSIS - LANGS TWO PENCIL TEST TITMUS STEREO TEST

BAGOLINIS STRIATED GLASSESSYMMETRICAL CROSSRESPONSE

NRCARC - HARMONIOUS

ASYMMETRICAL CROSS RESPONSE

INCOMITANT WITH ARC, DIPLOPIA

SINGLE LINE SUPPRESSION OTHER EYE

CROSS RESPONSE WITH CENTRAL GAP IN ONE LINE

CENTRAL SUPPRESION SCOTOMA IN THAT EYE

MADDOX ROD TEST• SINGLE MADDOX ROD TEST –

DETECTS PHORIA• DOUBLE MADDOX ROD TEST – PATIENT ASKED TO ALIGN THE

TWO LINES OF MADDOX ROD IN PARALLEL FUSION

MADDOX WING TEST

• RE – WHITE VERTICAL &RED HORIZONTAL ARROW

• LE – HOIZONTAL & VERTICAL ROWS OF NUMBERS

• HORIZONTAL DEVIATION – WHITE ARROW POINTS

• VERTICALDEVIATION - RED ARROW INTERSECTS• CYCLOPHORIA – RED ARROW PARRALLEL TO

NUMBERS

WORTH FOUR DOT TEST4DOTS NRC WITH NORNAL BSV

HARMONIOUS ARC , MANIFEST SQUINT

3DOTS SUPPRESSION RIGHT EYE

2DOTS SUPPRESSION LEFT EYE

5DOTS NRC WITH MANIFEST SQUINTESODEVIATION UNCROSSEDEXODEVIATION CROSSEDVERTICAL

SYNOPTOPHORE• SIMULTANEOUS PERCEPTION –

DISSIMILAR SLIDES• FUSION –

DISSIMILAR PERIPHERALS• STEREOPSIS –

SOME AREAS DISPARATE

STIMULATION, 3D EFFECT

AFTER IMAGE TESTING

• HIGHLY DISSOCIATING ORTHOPTIC TEST FOVEA FLASHED WITH LINEAR AFTER IMAGE , R/E HORIZONTAL, L/E-VERTICAL

• CROSS RESPONSE - NRC± SQUINT• ASYMMETRIC CROSSING – ARC + SQUINT,

DISPLACEMENT PROPORTIONAL TO ANGLE OF SQUINT

• SINGLE – SUPPRESSION

TESTING OF SUPPRESSION SCOTOMA• PRISM – TO DISPLACE OBJECT PARIPHERALLY TILL IT CAN BE

VISUALISED• SYNOPTOPHORE • HESS/ LEES SCREEN• POLAROID SCOTOMETER• GRADED DENSITY FILTER BAR OF BAGOLINI - DEPTH

STEREOACUITY• LANGS TWO PENCIL TEST – DIFFERENTIATES ARC FROM

SUPPRESSION• TITMUS STEREO TEST – VECTOGRAPH USED IN CHILDREN GROSS STEREOPSIS 3000 SECS OF ARC • RANDOM DOT STEREOGRAM & TNO TEST

FIXATION DISPARITY• FIXATION DISPARITY CURVES – UNDER FORCED VERGENCE WITH 3,6,9,12 Δ BASE IN / OUT

ALTERNATIVELY DISPARITY & ASSOCIATED PHORIA CHARTED• FORCED FIXATION DISPARITY CURVES – DIFFERENT SPHERICAL LENSES

2 TO 3 D IN 0.5 TO 1.0 STEPS USED TO MEASURES AC/A RATIO

• SHEEDYS DISPAROMETER – CENTRAL FIXATION TARGET 2 HALF SPLIT HORIZONTAL / VERTICAL LINES , EACH ½ VISIBLE TO ONE EYE

• WESSONS CARD – VIEWED THROUGH POLAROID GLASS; UPPER1/2 – VERTICALL LINES , LOWER1/2 - ARROW , REST SEEN BINOULARLY

MANAGEMENT• OPTICAL CORRECTION FOR REFRACTIVE ERROR CORRECTION• OCCLUSION THERAPY• ORTHOPTIC EXERCISE• OCULAR SURGERY

WEAKENING PROCEDURES

• RECESSION – SLACKENS MUSCLE BY MOVING IT AWAY FROM ITS INSERTION • DISINSERTION/ MYECTOMY – DETACHING

MUSCLE FROM ITS INSERTION WITHOUT REINSERTION• FADENS POSTERIOR FIXATION SUTURE –

DECREASES THE PULL OF MUSCLE IN ITS FIELD OF ACTION• MYOTOMY / TENOTOMY

STRENGTHENING PROCEDURES

• RESECTION – SHORTENS MUSCLE TO ENHANCE ITS EFFECTIVE PULL. CUT END REATTACHED TO ORIGINAL POSITION, ONLY FOR RECTI• TUCKING – OF MUSCLE / ITS TENDON TO

ENHANCE THE ACTION OF SO MUSCLE IN CONGENITAL 4 CN PALSY• ADVANCEMENT – OF THE MUSCLE NEARER TO

LIMBUS CAN BE USED TO ENHANCE THE ACTION OF PREVIOUSLY RECESSED RECTUS

GENERAL PRINCIPLES OF SQUINT SURGERY• 1MM RESECTION OR RECESSION OF MR CORRECTS 3

OF DEVIATION & FOR LR IT IS 2• MR SHOULD NOT BE RECESSED MORE THAN 5.5 MM

& FOR LR IT IS 7 MM• UNDERCORRECTION BETTER IN CHILDREN 5 – 10 • PREFERRABLE TO OPERATE ON ELEVATORS THAN ON

DEPRESSORS . 3MM RECESSION CORRECTS 10

CHOICE OF SURGERY• CONVERGENT SQUINT – MR RECESSION & LATERAL RECTUS

RECTION, MR RECESSION BOTH EYES• DIVERGENT SQUINT – LR RECESSION & MR RESECTION,

RECESSION LR BOTH EYES• ALTERNATING SQUINT – BIMEDIAL / BILATERAL RECESSION

CHEMODENERVATION• TEMPORARY PARALYSIS WITH BOTULINUM TOXIN• TO DETERMINE RISK OF POST OPERATIVE DIPLOPIA • TO ASSESS POTENTIAL FOR BSV• IN LR PALSY• COSMETICALLY POOR DEVIATIONS