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

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

3. Prevalance
World-2.76%
India- 2.72%

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

5. 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)

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

7. Types of squint
Alternating
Monocular

8. Congenital
Acquired
Familial

9. 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

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

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

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

13. Instruments

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

15. Head posture

16. Head posture Nystagmus

17. Fixation
Monoocular fixation
Binocular fixation

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

19. Visual acuity

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

21. 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

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

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

24. 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

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

26. Measurement in different gazes
To confirm Pattern deviations.

27. Measurement with optical correction

28. 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

29. 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

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

31. 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

32. 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

33. 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

34. 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

35. 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 .

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

37. 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.

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

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

40. Force duction test
Right lateral rectus palsy

41. Force generation test
Right lateral rectus palsy

42. Sensory evaluation

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

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

46. Thank you