The document discusses the evaluation of strabismus. It defines strabismus and the different types such as phoria, tropia, comitant, and incomitant. It describes the history to obtain and various tests used in the examination including motor function tests like cover test, versions, and ductions, and sensory tests like Worth 4-dot and Bagolini lenses. The document provides details on the order and components of a complete ocular examination for strabismus.

1. Dr Rakhi Dcruz
LVPEI,MTC,Bhubaneswar
EVALUATION OF STRABISMUS
23/10/19

2.  Strabimus –Greek word ‘Strabismos’ means to squint,to
look obliquely= ocular misalignment
Phoria : a latent deviation that is controlled by fusional
mechanisms,so that eyes remain aligned during binocular
movements
Tropia : a manifest deviation that exceeds the control of
fusional mechanisms
-constant
-intermittent
Pediatric ophthalmology&strabismus-BCSC-AAO

3. HISTORYOcular deviation
 Onset: Congenital orAcquired - precipitating event
 Duration
 Constant or intermittent
 Diurnal variation

4.  Past History
 Medical history
 Antenatal, Birth and Developmental history (in congenital
strabismus)
• Maternal illness, medication, fever with rash during pregnancy
 Developmental milestones (motor and intellectual – schooling)
 Old Photos

5. strabismus
TRUE
comitant Incomitant
Pseudostrabismus
Pseudoesotropia pseudoexotropia

6. TERMINOLOGY
1) Comitant : size of deviation doesn’t vary by more than few
prism diopters in different positions of gaze or with either
eye used for fixating.
2) Incomitant : the size of deviation varies with the eye used for
fixing
3) Primary deviation : deviation measured when the non paretic
or non-restricted eye is fixing
4) Secondary deviation : deviation measured when paretic or
restricted eye is fixing
Handbook of pediatric strabismus & amblyopia-Kenneth
wright,speigel,thompson

7. PSEUDOSTRABISMUS
Pseudoesotropia
• Due to flat nasal
bridge
• Prominent epicanthal
folds
• Narrow interpupillary
distance
• euryblepharon
Pseudoexotropia
• Wide interpupillary
distance
• Positive angle kappa
with or without
other ocular
abnormalities
Strabismus simplified-Pradeep sharma

8. ORDER OF EXAMINATION
1) Inspection :
2) Visual acuity
3) Sensory tests
4) Motor function tests
5) Cycloplegic refraction
6) Fundus examination

9. Motor evaluation tests
• EOM-ductions &
versions
• HBT
• Cover test
• Cover-uncover test
• Alternate cover test
• MKT
• PBCT
Sensory evaluation tests
• Worth 4 dot
• Bagolini
• 4 prism test

10. OCULAR EXAMINATION
Head posture:
 Best time when patient is reading vision chart
 Face turn, head tilt, chin up, chin down
 Thumb rules
Head tilt : Oblique muscle
Chin elevation :Vertical
rectus muscle
Face turn : Horizontal
muscle

11. CHIN DOWNHEADTILT &CHIN UP

12. FACETURN

13. HIRSCHBERGTEST
 Compares the position of corneal light reflection in both eyes, based on
purkinje image 1
 Degree of decentration of corneal light reflection
 1 mm of decentration = 70 = 15 PD
 Light reflex @ pupillary margin = 30 PD
 Light reflex @ mid iris = 60 PD
 Light reflex @ limbus = 90 PD
Handbook of pediatric strabismus & amblyopia-Kenneth wright,speigel,thompson

17. KRIMSKYSTEST
Adds prism to Hirschberg test to measure strabismus
 Krimsky’sTest
 Reflections produced on both corneas with penlight
 The prism is placed in front of deviating eye
 Moves the light reflex to the centre of pupil with out a version
shift
 Modified Krimsky’s test
 Prism is placed in front of focussing eye
 Causes version movement in which both eyes move in the
direction of the apex of the prism

19. COVERTEST
Pre requisites
1.Ability to maintain constant fixation on accommodative target
2.Foveal fixation in both eyes
3.Extra ocular muscles should be free
4.co-operative patient

20. COVERTEST
 Uses
 Differentiates true strabismus from pseudostrabismus
 Deviation is latent or manifest
 Fixation preference
 Gross idea about visual acuity
 Fixation targets
 Distance : 1 line above the BCVA
 Near : Accomadation target with discernable contours

21. COVERTEST
 Tropias are detected with out dissociating an existing phoria
 Cover the fixing eye just for 1-2 secs, not long enough which will
cause break up fusion and will manifest a phoria
 Cover one eye and check for movement of other eye
 Other eye moves outwards …. Esotropia
 Other eye moves downwards …hypertropia
Pediatric ophthalmology&strabismus-BCSC-AAO

22. UNCOVER TEST
 To check for phorias
 Cover the eye for few seconds and then uncover
 If the eye is deviated under cover a refixation movement is seen
 Eye on uncovering abducts--- esophoria
 Adducts …exophoria
 Downwards—Hyperphoria

23. ALTERNATE COVERTEST
In this test binocular fusion is dissociated there by which full
deviation can be measured
To determine full deviation including both phoria and tropia
One eye should always be occluded

25. PRISM ALTERNATE COVERTEST
 Done after alternate cover test which will give a estimate of size of
deviation
 Alternate cover test is done by placing prism in appropriate position
to neutralize deviation
 Determines the amount of prism to neutralize deviation
. Progressively increase strength of prism till no movement on
alternate cover test
Handbook of pediatric strabismus & amblyopia-Kenneth wright,speigel,thompson

27. 4PD BASE OUTTEST
 In normal subjects 4 base out test induces fusional convergence
 Initial version movement of both eyes in the direction of apex of
prism
 Fusional vergence movement of eye with out prism towards nose
 Patients with out motor fusion and large regional suppression shows
no movement of either eyes when prism is placed over non-
dominant eye
 Version movement of both eyes when its placed over fixing eye
 Handbook of pediatric strabismus & amblyopia-Kenneth wright,speigel,thompson

30. SENSORYTESTS
1) Includes diplopia tests and haploscopic tests
2) In diplopia tests one stationary target is viewed by both
eyes
3) In haploscopic tests have two fixation targets for each
eye and targets can be moves separately

31. DIPLOPIATESTS
Tests that disrupt fusion are referred to as dissociating tests
Includes
1) Maddox rod test
2) Worth 4-dot test
3) Bagolini striated lenses

32. MADDOX ROD
1) Consists of series of fused cylindrical red glass rods
2) Converts white spot of light into red streak
3) To test horizontal deviations Maddox rod is placed in such a
way the cylinders are positioned horizontally
4) If the light superimposes on the line it indicates orthophoria
5) If the light is to the left of the line it indicates esodeviation

34. WORTH 4 DOTTEST
 Dissociation test
 For near and distance
 Differentites between BSV,ARC and suppression
 Results interpreted in presence or absence of manifest
squint at the time of testing

36. WORTH 4-DOTTEST
 Patient wears red and green glasses
 Views a box of 4 lights- 1 red, 2 green and 1 white
 Results
 BSV– All 4 are seen
 2 red– Right suppression
 3 green– left suppression
 2 red and 3 green– Diplopia
 Green and red alternate – Alternating suppression
Handbook of pediatric strabismus &
amblyopia-Kenneth wright,speigel,thompson

37. BAGOLINI LENSES
These are clear lenses with a liner scratch through the centre
of lens that provides a streak of light on retina while viewing
a bright light
Oreinted obliquely at 450 and 1350 and are not dissociating

39.  if the two streaks form a oblique cross then the patient has
BSV or harmoniousARC
 If two lines are seen but they don’t form a cross it indicates
diplopia
 If only one streak is seen it indicates suppression
 Small gap in one of the streaks it indicates central
supressin scotoma

40. OCULAR EXAMINATION
 Posterior Segment
Bruckner'sTest
FundusTorsion
Eccentric Fixation (Foveal,
Parafoveal, Perifoveal)

41. In intorsion : fovea is above the lower half of the disc
In extorsion : fovea is below the lower half of the disc

42. OCULAR EXAMINATION
Extraocular Movement
 Ductions
 Versions
 Look for superior oblique and inferior oblique over
action: grading
 Convergence/divergence
 Forced DuctionTest, ForcedGenerationTest

44. Forced duction test :
Indicated -- evidence of restricted duction
For rectus muscles grasp the at limbus and rotate the eye in the field of
limited ductions
In right abduction limitation ask the patient to look right to relax tight
medial rectus muscle
Forced generation test
Assesses rectus muscle strength
Patient is asked to look into the field of limitation while the eyes are
held in primary position