1. ASSESSMENT OF A
SQUINT PATIENT
Siraj Safi
Lecturer in Optometry
PICO, HMC , Peshawar

2. Assessment Steps
1.
2.
3.
4.
5.
6.
History
Visual Acuity
Ocular Deviation
Ocular Movement
Binocular Function
Refraction

3. 1.History

4. 1.History
Patient with ocular motility disorder present
for one or more of the following reason:
 Manifest strabismus
 Defective ocular movement
 Nystagmus
 AHP
 Defective vision
 Subjective symptoms


5. 1.History continue….



The reason for attendance must first be
established.
In children greater emphasis is placed on
obstetric history and developmental miles stone.
Where as the medical history can be of
paramount importance in adult.

6. 1.History continue….
a. Medical history:




The child general development
Recent illness and treatment
Any trauma to the head and face
Any systemic disease
b. Obstetric history



The mothers health during pregnancy
Delivery
The child birth weight
c. Family history



Parental consanguinity
Strabismus
Refractive error

7. 1.History continue….
e. Strabismus in children:






The Direction of strabismus
The age at which it was first noticed
Who noticed it
Whether the onset was gradual or sudden
Frequency of deviation (constant or intermittent)
Previous treatment, if any, and the type and results of such
treatment
f. Strabismus in Adults:


Cosmetic
Subjective symptoms

8. 2.Visual Acuity

9. 2.Visual Acuity


Easy in adults or older children
Very difficult in infants.
But even than can be assessed by various
techniques

10. Normal visual development


From Alec. M Ansons and Helen Davis
The development of VA from birth to age three year
Age
New Born
I months
Visual Acuity
6/240
6/180 - 6/90
4 - 6 months
6/18 - 6/6
3 years
6/6
with single optotypes

11. Normal visual development

Age related VA estimated by test method
From Kenneth W. Wright
Technique
Birth
2 months
4 months
6 months
OKN
20/400
20/800
20/200
20/100
20/60
20-30 months
20/800
20/200
20/150
20/50
18-24 months
20/40
20/20
6-12 months
FPL
20/400
VEP
20/800
20/150
20/60
1 year
Age for 20/20

12. Age Indication For VA Tests

Age 0-6/12:
VEP ,FCPL, OKN, CSM, Objection to occlusion,
Catford Drum etc.

6/12 to 2 years:
100s & 1000s, Stycar balls, FCPL, Cardiff cards…

2 to 3 years:
Kay pictures, Illiterate E, Lea Symbol.........

3+ years:
Sheridan Gardener, Landolt C, Snellen , LogMar…….

13. CSM




The ability of each eye to fixate Centrally,
steadily, and Maintain fixation.
Centrally means foveal fixation
Steady means no nystagmoid movement
Maintain mean the ability of one eye to maintain
fixation when viewing is converted from a
monocular condition to a binocular condition.

14. 3.Ocular deviation

15. 3.Ocular deviation

Detection of Strabismus can be made
through:
Observation of the patient appearance
 Observation of the corneal reflex
 The cover test


16. 3.Ocular deviation cont…
 The cover test
It is an objective test which is the core stone of
investigation of strabismus.
Requires:
 Pin torch
 Occluder
 Target for 33cm and 6m

17. 3.Ocular deviation cont…
The cover test can be used in two ways:
1) The cover /uncover in which one eye is covered
and the observer notes:
a) The movement of the uncovered eye to take
up fixation.
b) The position and movement of the covered
eye as cover is removed.


18. 3.Ocular deviation cont…
2) Alternate cover test in which both eyes are
covers alternatively the movement of the
covered eye is noted as the cover is changed
from one eye to the other.
It is more dissociative than cover/uncover test

19. 3.Ocular deviation cont…

Information provided by the cover test:

Direction of deviation
The difference in angle from near to distance
The effect of accommodation
Comitance and incometance
Estimation of VA
The speed of recovery in latent strabismus
Constant ,intermittent, unilateral or alternating
Latent nystagmus or latent component in manifest
nystagmus
DVD
A/V Pattern










20. 3.Ocular deviation cont…
Confirmation and measurement of strabismus:
1. Hirschberg
2. Krimsky
3. Prism cover test
4. Simultaneous PCT
5. Maddox rod
6. Double Maddox rod
7. Maddox wing
8. Major amblyoscope
9. Diagnostic occlusion

21. 1.Hirschberg
Used as an initial screen for strabismus
How it works:
At 33cm front of child with penlight shining at eyes
Light reflection will be at the same point in each eye
Normal
Exotropia
Esotropia

22. 3.Ocular deviation cont…
1.
Hirschberg

23. 2.Krimsky Test
This test is used to centralize the corneal
reflection in the squinting eye with
compared to the fixing eye.

24. 3.Prism Cover Test
Measure squint/misalignment
 Single prism/prism bar
 Primary position or in all positions of gaze
 For near and distance


25. 4. SIULTANEOUS PCT




The prism is placed in front of the deviating eye
and a cover simultaneously introduced in front
of the fixing eye.
The aim is to neutralize the movement of the
squinting eye as the fixing eye is covered.
The test is performed with the same way by
increasing the strength of the prism until the
squinting eye did not move under the prism.
It grieves the estimation of tropia only.

26. 5.MADDOX ROD


Use of the Maddox rod
provides entirely subjective
method of measuring
horizontal, vertical and
torsional deviation . (Phoria)
Dissociation of the eye is
achieved by presenting a spot
light to one eye and a line
image to the other eye.

27. 6.Double MADDOX ROD




Torsional deviations:
Torsional deviation can be measured with
double Maddox rod.
The Maddox rod can be placed parallel in front
of both eyes better if have different color.
The patient is asked wither the both lines are
exactly align when placed parallel Maddox rod in
front of both eyes or vertical prism can be
introduced to separate the lines and than ask

28. 7.MADDOX WING


The Maddox wing dissociates the eyes by
means of two septa, so that the horizontal
and vertical measurement scales are
visible to the left eye and the right eye
sees the two arrows , one vertical to
indicate the horizontal measurement and
the other horizontal indicating the vertical
measurement for 33cm with correction.
Measurements are recorded in prism
dioptres

29. 8. Synoptophore
 Uses:




Angle of deviation
Assessment of retinal
correspondence
Fusional amplitude
Stereopsis

30. 9.DIAGNOSTIC OCCLUSSION
Diagnostic occlusion can be used to induce full
dissociation when it is thought that the maximum angle
of deviation has not been revealed.
Used in:
 Intermittent exotropia.
 To diagnose whether symptoms are due to hetrophoria.
 To differentiate between real or apparent limitation of
abduction in children.


31. 4.Ocular Movement

32. 4.Ocular Movement
A.
B.
C.
D.
E.
Clinical assessment and recording of ocular
movements
3- step test
Hess test
FDT
FGT

33. Muscle
Length of
active
muscle
(mm)
Origin
Anatomic
insetion
Direction innervation
of pull
Medial
Rectus
40
Annulus
Of zinn
5.5 mm from
Medical limbus
90o
Lower
CN III
Lateral
Rectus
40
Annulus
Of ainn
6.9 mm from
Lateral limbus
90o
CN VI
Superior
Rectus
40
Annulus
Of ainn
7.7 mm from
Superior limbus
23o
Upper
CN III
Inferior
Rectus
40
Annulus
Of ainn
6.5 mm from
Inferior limbus
23o
Lower
CN III
Superior
Oblique
32
Orbital apex Posterior to
above
Equator in
annulus of
Superotemporal
zinn
Quadrant
51o
CN IV
Inferior
Oblique
37
Behind
lacrimal
fossa
51o
Lower
CN III
Muscular area
near Macula

34. A way to remember




All obliques Abduct
All vertical Recti Adduct
All superior muscles Intort
All inferior muscles Extort

35. ocular movements





The ocular movements are of four types:
Ductions
Versions
Vergences
Supra nuclear movements

36. Ocular movements (terms)




Agonist muscle
Antagonist muscle
Yoke Muscles
Synergist
Laws of ocular motility


Sherrington law of reciprocal innervations
Hering Law of equal innervations

37. Full muscle sequelae will include




Primary paresis of the muscle
Over action of contralateral synergist
Contracture (O/A) of ipsilateral antagonist
Under action of contralateral antagonist (2ndry
inhibitional palsy)

38. Nine Position Of Gaze

39. The Diagnostic Positions of Gaze
RSR
LIO
RIO
LSR
R
RLR
LMR
RIR
LSO
L
RMR
LLR
RSO
LIR

40. H-PATTERN TEST
Instruction to the Px should be: “We are now going to assess how well your
eye muscles work together. I would like you to follow the target with your
eyes while keeping your head still. Let me know if you feel any pain on
eye movement or if you detect double vision at any time in the test.”
RSR
LSR
LIO
RIO
RLR
LMR
LLR
RMR
RIR
LIR
LSO
RSO

41. Recording of Ocular Movements
Grid form
Rt. Gaze
Lt. Gaze
RT .SR
LT .IO
RT .IO
LT .SR
RT .IR
LT .SO
RT .SO
LT .IR

42. Recording of Ocular Movements
Grid form
Rt. Gaze
Lt. Gaze
Rt+/ Lt-
Rt-- / Lt++
E.g. RT SO Palsy

43. Recording of Ocular Movements

Diagrammatic form
Rt. eye
Lt. Eye

44. Recording of Ocular Movements





Descriptive form:
e.g..
Rt. Medial rectus is under acting -2
or
Rt. MR u/a -2
Rt. MR u/a --

45. Three – Step Test

46. Three – Step Test



Superior oblique palsies are often diagnosed
using the three-step test.
There are eight cyclovertically acting muscles;
four work as depressor of the eye and four work
as elevators of the eye.
Four in each eye.

47. Step-1
Determine which eye is hypertropic by using the
cover test.
Step-1 narrows the number of possibly under
acting muscles from eight to four

e.g. Rt hypertropia:
This means that either the depressors of the Rt eye are weak
(RIR,RSO) or the elevators of the Lt eye are weak (LIO,LIR).
Draw an oval around them

48. R Hypertropia
Elevators of L eye
RSR
RIO
LIO
LSR
RSO
LIR
RIR
RSO
Depressors of R eye
LSO

49. Step-2

Determine whether the vertical deviation is
greater in Rt gaze or in Lt gaze.

e.g. in Lt gaze. This implicates one of the four vertical acting
muscles used in left gaze, the two possible muscles at this point
are either both intortors or both extortors. Draw an oval around
the four vertically acting muscles that are used in Lt gaze.
It may be either the RSO or LSR. These are the only muscles

circles twice.

50. R Hypertropia
RSR
RIO
LSR
LIO
RSO
RIR
RSO
RSO
LIR
LSO
Left Gaze

51. Step-3



This step is also known as Bielschowsky head tilting
test, it involves tilting the head to the Right then to the
Left.
Head tilt to the Right stimulate intorsion of the Rt eye
(RSR,RSO) and extorsion 0f the L eye (LIR,LIO) and
vice versa.
e.g. in the same case suppose that the vertical deviation increases
to the Rt tilt. This implicates the four muscles that act vertically
in the R tilt position. Draw an oval around these muscles. Note
that the RSO is the only muscles that is surrounded by three
ovals.

52. RIO
LSR
LIO
LIO
RSR
RSO
RIR
Tilt to R side
RSO
RSO
Rt. SO Palsy
LIR
LSO
Left Gaze

53. Hess test

54. Principle of test
1. Dissociation of the eyes by either:


Red and Green goggles in case of Hess.
The mirror in case of Lees Screen.
2. Foveal projection in the presence of normal retinal
correspondence.
3. Herring’s and Sherrington’s Law:
Explain the development of muscle sequelae.

55. Uses of Hess Test
1. Diagnosis of
 Underaction or Overaction of EOM.
 Mechanical or Neurogenic palsy.
 A or V pattern
2. Planning of surgery and post-op effects of
surgery
3. Monitoring of condition.

56. How to interpret

57. How to interpret

58. 4.Ocular Movement
 FDT force duction test:
The purpose of the force duction test is to
assess passive movement of the globe in case in
which active ocular movements are limited
either neurologically or mechanically.

59. 4.Ocular Movement
 FGT force generation test:
The force generation test assesses the active
muscle force which enables eye movement to
take place.
The aim of the test is to calculate the potential
force in an apparently paralised muscle.

60. 5.Binocular Function

61. Investigation of BSV






It can be done through:
Bagolini Glasses
Worth 4 lights
Prism reflex test
4 ∆ Prism test
Stereo acuity tests

62. Bagolini glasses


Apparatus consists of a pair of plano- glasses
marked with fine parallel striation of 45o & 135o on
the other.
Line image is formed at 90o of striation.

63. Bagolini glasses
Test distance

Can be used at 6m & 33cm
Position of Gaze


Can be used in any desired gaze
Upward and downward gaze especially in
“A” &“V” pattern

64. Worth 4 light test
It consists of four circular lights
 Two green lights
 One red light
 One white light.

65. Worth 4 light test
Test’s Phenomenon



Red light is seen through red filter.
Green light is seen through green filter.
White light is seen by both eyes.

66. Worth 4 light test
Results
1. 4 lights indicates BSV either normal or less usually
abnormal.
2. 2 lights are seen if left suppression is present.
3. 3lights are seen if there is right suppression.
4. 5 lights are seen if diplopia is present.

67. Prism reflex test



The prism is used to assess the motor system of the
patient.
A 15∆ to 20∆ is placed in front of one eye and
response of the other eye is seen.
A response should be obtained in infants aged 6
months and up ward.

68. Prism reflex test
Results



If all three movements are seen motor fusion is
present, however Asymmetry of movement should be
noted.
If the eye behind the prism fails to adduct then there
is a scotoma present in that eye.
If the other eye fails to recover then it indicates that
suppression prevented the recovery or lack of motor
fusion.

69. 4 ∆ Prism test

The main aim of the test is to prove the
presence of normal binocular single vision.

70. 4∆ Prism test
A 4∆ prism is placed in front of one eye and the
recovery is noted.
The strength of image moves the image a little bit in
the foveal area, if the recovery and movement is seen
then there is no scotoma present.
Prism can be used B.I, B.O, B.U & B.D.

71. Stereo acuity






Include :
Lang two pencil test
Titmus Fly Test
The Frisby Stereo-test
TNO test
The Lang Stereo-test

72. Tests for Stereopsis
(Qualitative Tests)
Lang 2 pencil test
Method:
Pt places the pencils tip on the tip of the
examiner’s pencil.
Result:
It is a test mainly used for the detection of
gross stereopsis.
1.

73. Titmus Fly Test – Polaroid Vectograph

74. Titmus Fly Test – Polaroid Vectograph
This test uses crossed Polaroid filters to present
slightly different aspects of the same object to
each eye. The test comprises of three sections:
•
The Housefly - which shows large disparities and
should be seen in depth by most subjects.
•
Circle Patterns – this section consists of patterns
containing four circles. One of the circles in the
pattern contains a graded disparity (crossed), so
that when it is viewed binocularly it is seen to
float in front of the others. The disparities of the
circles range from 800 to 40 secs of arc.
•
Animals – there are 3 rows of animals, one
animal in each row having a crossed disparity
which ranges from 400 – 100 secs of arc.

75. The Frisby Stereo-test

76. The Frisby Stereo-test
This is the only clinical test based on actual depth, where random
shapes are printed on three clear plastic plates of different
thickness.
The test does not require any form of dissociation.
Each plate has 4 squares of curved random shapes, and one
square contains a hidden circle that is printed on the opposite
surface. Disparities range from 600 to 15 secs of arc.
Care should be taken that neither the plates nor the Px’s head
move significantly during the testing procedure, as this may
provide monocular cues.
If the first plate is recognised successfully then the thinner plates,
which give smaller disparities, are presented in a similar fashion.

77. The TNO Test

78. TNO
Each test plate consists of a stereogram in which the
images presented to each eye have been
superimposed and printed in complimentary colours.
The stereograms are viewed through a pair of red
and green filters.
The random dot stereograms have the advantage
that they completely eliminate monocular cues, the
patient is required to describe the shape which can
only be seen stereoscopically.

79. The TNO test has 7 plates.
The first four plates are for screening purposes, the disparities are large and
ungraded.
Plate I
2 butterflies are present, one can be seen
monocularly, the other is only seen in stereopsis.
Plate II
4 discs, 2 are seen monocularly two require
stereopsis.
Plate III
four hidden shapes (O, , ∆, ) are arranged around a
centrally placed cross
Plate IV
This is a suppression test. There are 3 discs, one
seen by the right eye, one by the left, and one is seen
binocularly.
Plate V-VII
Here the test items (Pac-man Shapes) are presented at 6
different disparities ranging from 15 – 480 secs of arc.

80. Plate V
Plate VI
Plate VII
480
120
30
240
60
15

81. The Lang Stereo-test

82. Lang
The test consists of vertical sections that are seen
alternately by each eye as they are seen through in-built
cylindrical lens elements.
Displacement of the random dots creates the disparity
which ranges from 1200 to 550 secs of arc.
The cards are held at the subject’s reading distance and he
or she is asked to name or point to the pictures.

83. 6.Refraction

84. Cycloplegia and retinoscopy



Accurate refraction in children usually requires
full cycloplegia.
Adequate cycloplegia for retinoscopy may be
obtained in 60 minutes following the instillation
of cyclopentolate 1% eye drops.
Below the age of three months mydriatics are
used in lower concentration to reduce the risk of
toxicity.

85. Refraction


The routine use of atropine for diagnostic
cycloplegia or mydriasis is unnecessary and may
cause harmful side-effects.
However, in patients with darkly pigmented
irides cyclopentolate may prove insufficient for
full cycloplegia and it may be necessary to use
atropine eye drops or ointment.

86. Correction of refractive error
Hypermetropia :



In all forms of esotropia, full correction of
hypermetropia is the treatment of choice.
In practice, a reasonable lower limit for spectacle
correction is + 1.50 dioptres (+ 3.00 ret. @ 2/3
metre).
When prescribing, 'full correction' means that
only the working distance is allowed for with no
subtraction for cycloplegia.

87. Refraction
Hypermetropia :



In esophoria full correction
In exophoria or tropia under correction
In children without strabismus the precise
indication for treatment of spherical errors is ill
defined and will depend on the age of the child
symptoms and the magnitude of the error.

88. Refraction





Myopia
In esophoria or tropia under correction
In exophoria or tropia full correction or even over
correction
High myopia (-6.00 D or more) may require correction
in infancy and moderate myopia (4.00 D or more) in
two year olds and older children.
Lesser degrees of myopia do not usually cause
problems in small children and prescription can be
based on subjective refraction over the age of six years.