DIAGNOSTIC EVALUATION DIAGNOSTIC EVALUATION FOR STRABISMUSFOR STRABISMUS

Ms. JayaRajini Vasanth Mphil, B.S (opt)Ms. JayaRajini Vasanth Mphil, B.S (opt)

Assistant Professor – OptometryAssistant Professor – Optometry

Ophthalmology DepartmentOphthalmology Department

Sri Ramachandra University Sri Ramachandra University

Classification of strabismusClassification of strabismus

A.A. Pseudostrabismus (false or Pseudostrabismus (false or apparent squint).apparent squint).

B. True strabismus:B. True strabismus: 1. Latent squint (heterophoria).1. Latent squint (heterophoria). 2. Manifest squint (heterotropia): 2. Manifest squint (heterotropia):

- non- paralytic - non- paralytic (concomitant).(concomitant).

- paralytic (non- concomitant).- paralytic (non- concomitant).

Axes of the eyeAxes of the eye

Visual axis:Visual axis: Line passes from the fovea to the point of fixation Line passes from the fovea to the point of fixation (object of regard). The normal visual axes (from both (object of regard). The normal visual axes (from both eyes) intersects at the point of fixation.eyes) intersects at the point of fixation.

Optical axis:Optical axis:

It is the line passing through the centre of the It is the line passing through the centre of the cornea and meets the retina on the nasal side of the cornea and meets the retina on the nasal side of the foveafovea

Fixation axis:Fixation axis:

It is the line joining the fixation point and the It is the line joining the fixation point and the centre of rotation centre of rotation

Angle kappa is the angle between visual (0ptical) axis Angle kappa is the angle between visual (0ptical) axis and the anatomical (pupillary) axis. and the anatomical (pupillary) axis.

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As the fovea lies just temporal to the anatomical axis, a As the fovea lies just temporal to the anatomical axis, a light shown into the cornea will cause reflex (on the visual light shown into the cornea will cause reflex (on the visual axis) just nasal to the center of the cornea in both eyes axis) just nasal to the center of the cornea in both eyes (+ve angle kappa = 5°).(+ve angle kappa = 5°).

In high myopia the, the fovea lies nasal to the In high myopia the, the fovea lies nasal to the optical axis. So, the corneal reflex lies temporal optical axis. So, the corneal reflex lies temporal to the center of the cornea simulating esotropia.to the center of the cornea simulating esotropia.

Negative angle kappa (myopia) leads to pseudo-Negative angle kappa (myopia) leads to pseudo-esotropia.esotropia.Large positive angle kappa (hypermetropia) Large positive angle kappa (hypermetropia) leads to pseudo-exotropia.leads to pseudo-exotropia.

PseudostrabismusPseudostrabismus

In young infants, In young infants, strabismus must be strabismus must be differentiated from the differentiated from the more common more common pseudostrabismuspseudostrabismus

PseudoesotropiaPseudoesotropia as a result of a broad bridge of the nose. This is not a real eye crossing

Pseudo-deviationsPseudo-deviations

Pseudo-esotropiaPseudo-esotropia Pseudo-exotropiaPseudo-exotropia

•Epicanthic folds

Short interpupillary distance

•Negative angle kappa

•Wide interpupillary distance

Positive angle kappa

HISTORYHISTORY Age of onset of deviationAge of onset of deviation Is the deviation constant or intermittent?Is the deviation constant or intermittent? Is the deviation present for distance, near or both?Is the deviation present for distance, near or both? Is it unilateral or alternating?Is it unilateral or alternating? Is it present only when the patient is inattentive or Is it present only when the patient is inattentive or

fatigued?fatigued? Is it associated with trauma or physical stress?Is it associated with trauma or physical stress? Old photographsOld photographs Birth historyBirth history Is there a family history of strabismus?.Is there a family history of strabismus?. Are there any other medical problems? Are there any other medical problems?

HeadachesHeadaches Is there a history of toxin or medication exposure?Is there a history of toxin or medication exposure?

VISUAL ACUITYVISUAL ACUITY

Recognition acuity : Lea symbols, HOTV, Snellen ChartRecognition acuity : Lea symbols, HOTV, Snellen Chart

Detection acuity : Stycar Ball testDetection acuity : Stycar Ball test

Resolution acuity : Lea PaddlesResolution acuity : Lea Paddles

SENSORY EVALUATIONSENSORY EVALUATION

Simultaneous macular perceptionSimultaneous macular perception

Worth four dot testWorth four dot test

StereopsisStereopsis

Tests for sensory anomaliesWorth four-dot test

a - Prior to use of glassesb - Normal c - Left suppression/ amblyopia

Bagolini striated glasses

a - Normal or ARCb- Diplopiac - Suppression

d - Right suppression/ amblyopiae - Diplopia

d - Small suppression scotoma

Tests for StereopsisTests for StereopsisTests on stereopsis can be based on two principles- Tests on stereopsis can be based on two principles- 1.Using targets which lie in two planes, but are so 1.Using targets which lie in two planes, but are so

constructed that they stimulate disparate retinal constructed that they stimulate disparate retinal elements and give a three dimensional effect, for elements and give a three dimensional effect, for example: example:

Circular perspective diagram such as the concentric Circular perspective diagram such as the concentric rings rings

Titmus fly test, TNO test, Random dot stereograms, Titmus fly test, TNO test, Random dot stereograms, Polaroid test Polaroid test

Langs stereo test Langs stereo test Stereoscopic targets presented haploscopically in Stereoscopic targets presented haploscopically in

major amblyoscope major amblyoscope 2.Using 3 dimensional targets (e.g. Lang’s two 2.Using 3 dimensional targets (e.g. Lang’s two

pencil test). pencil test).

Qualitative tests for Qualitative tests for StereopsisStereopsis: : Lang’s 2 pencil test Lang’s 2 pencil test Synoptophore Synoptophore

Quantitative tests for Quantitative tests for Stereopsis:Stereopsis: Random dot test Random dot test TNO Test TNO Test Lang’s stereo test Lang’s stereo test

Tests for stereopsisTitmus

• Red-green spectacles

TNO random dot test

• ‘Hidden’ shapes seen • Polaroid spectacles• Figures seen in 3-D

Lang

• No spectacles

Frisby

• ‘Hidden’ circle seen

• No spectacles• Shapes seen

MOTOR EVALUATIONMOTOR EVALUATION

Extra ocular musclesExtra ocular muscles Cover testCover test Corneal reflex test – HirschbergCorneal reflex test – Hirschberg

KrimskyKrimsky

BrucknerBruckner Dissimilar image test – Maddox rod Dissimilar image test – Maddox rod

Evaluation of MotilityEvaluation of Motility

Two principle methods of evaluating ocular motility Two principle methods of evaluating ocular motility are: are:

11. Observation of ocular ductions, which are the . Observation of ocular ductions, which are the actual monocular movements of the eye.actual monocular movements of the eye.

22. Observation of binocular ocular alignment, using . Observation of binocular ocular alignment, using cover/uncover and alternate cover testing. cover/uncover and alternate cover testing.

Monocular eye movementsMonocular eye movements

A- elevation B- depression C- adbuction d- adduction E–extortion F- intortion

Ocular movement examinationOcular movement examination

Right esotropia (RETRET)Right exotropia (RXTRXT)Right hypertropia (RHTRHT)right hypotropia  Left esotropia (LETLET)Left exotropia (LXTLXT)Left hypertropia (LHTLHT)left hypotropia Alternating esotropia (ALT ETALT ET)Alternating exotropia (ALT XTALT XT)

EE esophoriaXX exophoria

RHRH right hyperphoriaLHLH left hyperphoria

E(T)E(T) intermittent esotropiaX(T) intermittent X(T) intermittent exotropiaexotropiaRH(T)RH(T) intermittent right hypertropiaLH(T)LH(T) intermittent left hypertropia

Cover test detects heterotropia

•Uncover test detects heterophoria

•Alternate cover test detects total deviation

•Prism cover test measures total deviation

Motility testsMotility testsTests versions and ductionsTests versions and ductionsGrades under/overactionGrades under/overaction

Left inferior oblique overaction Left lateral rectus underaction

Hirschberg‘s testHirschberg‘s test

Amount of deviation: note location of corneal light Amount of deviation: note location of corneal light reflex reflex

1 mm = 71 mm = 7°° or 15 or 15ΔΔ

Reflex at border of pupil = 15°° Reflex at limbus = 45°°

Hirschberg’s TestHirschberg’s Test

Used as an initial screen for Used as an initial screen for strabismusstrabismus

How it works:How it works:

Stand several feet in front of Stand several feet in front of child with penlight shining child with penlight shining at eyesat eyes

Light reflection will be at the Light reflection will be at the same point in each eyesame point in each eye

Normal

Exotropia

Esotropia

Krimsky TestKrimsky Test

Modified Krimsky testModified Krimsky test Asymmetric positions of the corneal Asymmetric positions of the corneal

reflex in the pupils of each eye are reflex in the pupils of each eye are indicative of strabismus, which may indicative of strabismus, which may be measured by placing a prism be measured by placing a prism before the fixating eye until the before the fixating eye until the reflection is similarly positioned in reflection is similarly positioned in both eyesboth eyes

Base out prism for esotropia and Base Base out prism for esotropia and Base in prism for exotropiain prism for exotropia

This is the direct reading of the squint This is the direct reading of the squint angle.angle.

Bruckner TestBruckner Test Is performed by using Is performed by using

direct ophthalmoscope direct ophthalmoscope to obtain a red reflex to obtain a red reflex simultaneously in both simultaneously in both eyes.eyes.

If there is strabismus , If there is strabismus , the deviated eye will the deviated eye will have a lighter and have a lighter and brighter reflex than the brighter reflex than the fixing eye.fixing eye.

Media opacities, Media opacities, Refractive errors, Refractive errors, StrabismusStrabismus

Dissimilar image testsDissimilar image testsMaddox wing Maddox rod

•Dissociates eyes for near fixation (1/3 m)•Measures heterophoria

•White spot converted into red streak

•Cannot differentiate tropia from phoria

Measurements of ocular Measurements of ocular misalignmentmisalignment

Measurement of Measurement of squints/misalignments squints/misalignments

Synoptophore - picture Synoptophore - picture test test

Measure - misalignments, Measure - misalignments, sensory and motor fusion sensory and motor fusion and stereopsis and stereopsis

Predict BV post-surgery Predict BV post-surgery Measure misalignments 9 Measure misalignments 9

positions of gaze positions of gaze

Prism Cover TestPrism Cover Test

Measure Measure squint/misalignment squint/misalignment

Single prism/prism bar Single prism/prism bar Primary position or in all Primary position or in all

positions of gaze positions of gaze