Evaluation of strabismus Dr. K.Veena Aravind Eye Hospital Pondicherry

Misalignment of eyes in a particular direction What is Squint? Misalignment of eyes in a particular direction

Prevalance World-2.76% India- 2.72%

Convergent or Esodeviation-E Divergent or Exodeviation……..X Vertical R/L or L/R

Common squint abbreviations Heterophoria Near Dist Heterotropia Near Dist Intermittant Esodeviation E’ E ET’ ET E(T)’ E(T) Exodeviation X’ X XT’ XT X(T)’ X(T) Rt hyper LT hyper RH’ RH LH’ LH RHT’ RHT LHT’ LHT RH(T)’RH(T ) LH(T)’ LH(T)

Heterophoria - Latent squint. - Fusional control is always present Intermittent tropia - Occasional squint. - Fusional control is not constant. Heterotropia - Constant squint. - Fusional control absent

Types of squint Alternating Monocular

Congenital Acquired Familial

Goals of strabismus examination To establish the cause of the strabismus Pseudo-strabismus Congenital or Acquired Paralytic or Restrictive pathology Assess the binocular motor and sensory status Measure the deviation Diagnose amblyopia

History Onset of strabismus Deviation Character of strabismus Diplopia Old photographs Antenatal &Perinatal history 10

Past History Patching Spectacle wear Type of strabismus Trauma – Blowout fracture Previous surgery Strabismus surgery RD surgery Cataract surgery Glaucoma implant

Inspection Observe the child as he/she enters your clinic While taking history Patients visual behaviour Eye movements Ocular Alignment Head & face posture IQ

Instruments

Physical Examination Observation Visual acuity assessment Motor & Sensory evaluation Movements Measurement of deviation Special tests for identifying restriction & paresis Cycloplegic refraction Fundus examination

Head posture

Head posture Nystagmus

Fixation Monoocular fixation Binocular fixation

Measuring ocular deviation-Light reflex test Hirschberg test Each mm decentration is equal to 7° / 15 pd

Visual acuity

Bruckner Test Detects presence of ocular abnormalities through the pupil Dim illuminated light, direct ophthalmoscope, coaxial illumination Strabismus, Ametropia, Lens opacity, Retinal pathology

Ocular deviation Broad epicanthal folds Pseudo exotropia To r/o Pseudo strabismus Angle kappa Broad epicanthal folds Flat nasal bridge Small inter pupillary distance Pseudo exotropia Positive angle kappa Wide interpalpabral distance

Cover test To detect strabismus Prerequisites Central fixation Good vision Normal range of movements

Cover – Uncover test Detect the presence of manifest strabismus to differentiate between Phoria and Tropia

Alternate Cover Test Measures total deviation both latent and manifest Cover is placed alternatively in front of each eye to dissociate the eyes and maximize deviation

Measurement of deviation Prisms-The amount of prism power required neutralize the deviation is the measure of deviation Primary deviation Secondary deviation

Measurement in different gazes To confirm Pattern deviations.

Measurement with optical correction

Krimsky Test (Prism reflex, prism reflection test) Prism use to move the corneal reflection in the deviating eye to a position similar to that of a corneal reflection in a fixating eye

Modified Krimsky Test If the deviating eye is densely amblyopic / blind prisms of increasing strength are placed infront of the fixing eye Until the corneal reflection become central in the deviating eye

Prism adaptation test Predictive value of when fusion may be restored following surgery In small angle deviation In acquired esotropia To determine target angle

Three step test: Step 1. Which eye is higher (hypertropic)? Easiest to learn by example If right hyper, circle muscles that pull right eye down or pull left eye up IO SR IR SO

Step 2. Hypertropia worse in left or right gaze? If worse in gaze left, circle muscles on the patient's left IO SR IR SO

Step 3. Is the hypertropia worse in left or right tilt Step 3. Is the hypertropia worse in left or right tilt? (Bielschowsky head tilt test) worse when head tilted to the right tilt Circles to the patient's right IO SR IR SO RS

Three step test: Conclusion Only one muscle was circled three times This must be an isolated paresis of the RIGHT SUPERIOR OBLIQUE MUSCLE IO SR IR SO RS

Hess chart Quantitative assessment of incomitant strabismus Prognostic guide with respect to the change with time and to record progressive changes. Planning treatment To compare pre and post operative muscle balance .

Prerequisites Incomitant strabismus Normal retinal correspondence Central fixation Only if patient has some fusion, otherwise suppression or alternation will occur when attempting to superimpose.

Diplopia charting 1.Record of separation of the diplopic images in the 9 positions of gaze 2. Useful particularly in Torsional diplopia Patient is bed ridden Unable to plot hess chart Unable to plot binocular field of fixation Esotropia: There is Nasal Disparity leading to Uncrossed Diplopia. Exotropia: There is Temporal Disparity leading to Crossed Diplopia.

Synaptophore IPD Detect & measure deviation SMP Fusion Stereopsis Fusional exercises Macular function test After image test

Special tests Forced duction test Forced generation test Differential IOP test Saccadic velocity EMG Tensilon test

Force duction test Right lateral rectus palsy

Force generation test Right lateral rectus palsy

Sensory evaluation

Cyloplegic Refraction & Fundus Examination NEVER DIAGNOSE A CASE OF STABISMUS WITHOUT FUNDUS EXAMINATION

Investigations Blood investigations X-ray orbits B scan orbit CT scan/MRI

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