Strabismus Patients Evaluation

1. Mohammad Sazzad Hossen
B. Optom (VMU), M. Optom(CO), India
ICLEP (LVPEI, Hyderabad)
Trained from TSNA (Chennai), IIEIH (Dhaka), CEITC (Ctg.)
Consultant Optometrist - Ad-din Medical College Hospital

2. Definition
Strabismus
Case Studies
Anatomy
Assessment
Management

3. Strabismus is a visual problem in which the eyes
are not aligned properly and point in different
directions. One eye may look straight ahead,
while the other eye turns inward, outward,
upward, or downward.

5. SQUINT
Apperent squint
(Pseudo-squint)
Latent squint
(Hetro-phoria)
Comitant
Paralytic/Paresis Ristrictive Spastic
Incomitant
Manifest squint
(Hetro-tropia)
Squint

6. Concomittant (non paralytic)
Monocular
 Eso Tropia or Convergent
 Exo Tropia or Divergent
 Hyper Tropia
 Hypo Tropia
 Incyclo & Excyclo
Alternating
 Convergent
 Divergent

7. Inward turning is called
esotropia
Outward turning is called
exotropia
Upward turning is called
hypertropia
Downward turning is called
hypotropia.

8.  b-PARALYTIC STRABISMUS
 1- 3RD( oculomotor)cranial nerve palsy(all
extraocular muscles involved except the lateral
rectus & the superior oblique muscle)
 2- 6th cranial nerve (abducent)=paralysis of
lateral rectus muscle .
 3- 4th cranial nerve (trochlear)=paralysis of
superior oblique muscle

9. Causes of acquired ocular motility disorder
Neurogenic (ocular motor nerve lesion):
Vascular (diabetes or hypertention).
Demyelinating (multiple sclerosis).
Inflammatory
Compressive (aneurysm or tumour)
Trauma or surgery.
Myogenic
Myasthenia gravis
Ocular myopathy
Restriction
Dysthyroid ophthalmopathy
Trauma
Inflammation
Orbital
Orbital mass restricting eye movement

10. Convergence Insufficiency.
 Students usually suffer from this problem.
 A third type of exotropia is an apparent weakness of
convergence, called convergence insufficiency. The entity
frequently affects young adults and is a major cause of
asthenopia, or tired eyes, while doing near work in this age
group.

11. Risk factors for developing strabismus include:
Family history – individuals with parents or siblings who
have strabismus are more likely to develop it.
Refractive error – people who have a significant amount
of uncorrected farsightedness (hyperopia) may develop
strabismus because of the additional amount of eye
focusing required to keep objects clear.
Medical conditions – people with conditions such as
Down syndrome and cerebral palsy or who have suffered
a stroke or head injury are at a higher risk for developing
strabismus.

13. HISTORY
INSPECTION
VISUAL ACUITY & REFRACTION
EVALUATION OF MOTOR STATUS
HBCT/KRIMSKY/CT
EVALUATION OF SENSORY STATUS (STEROPSIS/
SUPPRESSION /ARC OR RC)
MEASUREMENT OF DEVIATION
ANT.& POST.SEGMENT
SPECIAL TEST TO IDENTIFY PARESIS & RESTRICTION

14. HISTORY
 Age of Patient
 Complaint:-
o Age of Squint onset (early onset/ long duration / constant angle / previous photos)
o Is it Sudden Or Gradual ?
o Direction of deviation patient / parent noted
o Is it Constant? Or Sometimes (INTERMITTENT)
o Noticed in One Eye or Both?
(U/L OR ALTERNATE)
o Diplopia? Asthenopia? Abn.Head Posture
 Birth History
o Regarding Pregnancy & Delivery
o Developmental Milestones(Delay)
 Family History
o Squint/ Refractive Error / Lazy eye
 Personal History
o DM /HTN / Thyroid
 Treatment History
o Glasses /Occlusion Therapy /Orthoptic Exercise / Prev. Surgery

15. .….Looks can b really Deceptive
 Lid Fissure:-
 Ptosis
 Mongoloid/Anti mongoloid
 Exophthalmos / enophthalmos
 Nasal Bridge
 Closure of one eye in bright light
 Epicanthal folds
 Head Posture (AHP)
 Face Turn (Right/Left)
 Head Tilt (Right/Left Shoulder)
 Chin (Elevation/Depression)
 Facial Asymmetry
 Fixation Preference
 Nystagmus
INSPECTION

17. Extra-Ocular Movements
EOM
MONOOCULAR BINOCULAR
VERSIONS
(Conjugate
Movements)
VERGENCES
( Disconjugate
Movements)

18. Points to Remember for EOM
 To check if all eye muscles r working together.
 Patient and examiner positioned at same level
 Room should be properly illuminated.
 Sit in front of the patient so that BE eyes can be seen simultaneously.
 Remove any Spectacles.( to remove prismatic effect)
 USE A PENLIGHT.
 40 CM DISTANCE,SHINE ON FOREHEAD
 Move in 6 diagnostic/H position.

19.  ADDUCTION:- is normal when NASAL 1/3RD CORNEA crosses nasal punctum
 ABDUCTION:- is normal when TEMPORAL LIMBUS touches lateral canthus.
 INFERIOR OBLIQUES:- on lateral version , upwards deviation from the
horizontal line passing through centre of pupil
 SUPERIOR OBLIQUES :- on lateral version, downwards deviation from
the horizontal line.
 ELEVATION :-
 DEPRESSION :-

20. Objective Test Subjective Test
 Hirshberg Test
 Prism Alt.Cover Test(PACT)
 Krimsky Test
 Maddox Rod
 Hess Screen Test
 Synaptophore Test

21. Dissociation of Eyes
 Cover test
 Diplopia or displacement tests (vertical ∆)
 Distortion tests (Maddox Rod)
 Independent objects (Maddox Wing)

22. PRE-REQUISTE FOR CT/CUT/ALT
 Simplest method
 Objective assessment
 Vision More than 6/60 in BE to see the target
 Central fixation in BE
 If Bifocals are worn, near deviation measured through
reading segment
 Cover test only way to distinguish between phoria and
tropia
 Perform on all patients with and without Rx

23. Cover Test / Cover-Uncover/
Alternate Cover Test
 Helps to establish Ortho-tropic or not.
 Is Squint Latent= Phoria
 Is Squint Manifested = Tropia
 Direction of Deviation
 Fixation Behavior
 Check for Distance & Near
Patient fixates on smallest letter seen by
poorest eye. Use an opaque occluder
Don’t go too quickly
Cover placed before 1 eye and then removed
Observe the uncovered eye for movement; if
movement is present then patient has a squint
If a squint is present there cannot be a phoria

24. Cover Test
 Covering one eye of patient with
normal binocular vision interrupts
fusion.
 See for the movement OF OTHER
EYE
 When eye is uncovered ,it will
reestablish binocular fixation
 Imp. of Test:- Detects & Confirms
Tropias

25. Cover- Uncover Test
 Examiner OBSERVE THE
COVERED EYE AS COVER IS
REMOVED.
 In Hetrophoria,covered eye will
deviate toward hetrophoric
position.
 When eye uncovered 
Reestablish Binocular Vision.
 Imp.of Test:- used to find out
PHORIAS

26. Alternate Cover Test
 Identify (Tropia + Phoria)
 Hold occluder over one eye for
several seconds
o Dissociates binocular vision
 Rapidly move occluder to other
eye
 Observe Refixation shift of
unoccluded eye

27. Prism Cover Test by Prism Bar
Base Out for EP and ET
Base In for XP and XT

28. Distortion Test
 Maddox Rod
 Can be used for vertical and horizontal deviations

29. Maddox Rod
 Place rod before right eye
 Use spot light and dim room lights
 Ask “ is red line to the left or right of the
spotlight?”
 If rod is to the right SOP
 If rod to the left XOP
 Use prism to align rod and spotlight

30. Maddox Rod

31. Hirschberg Corneal Reflex (HBCT)
 1mm shift = 7° or 15 *Uses 1st Purkinje Image
00ºº
1515ºº
4545ºº
2828ºº

32. Krimsky Test /Modified HBCT
 Angle of strabismus is evaluated,
when the light is projected straight
ahead, and subsequent prisms
(prism bar) are placed
 Based on HERING’s LAW of
equal innervation
BEFORE THE FIXING EYE
until symmetrical light reflexes are
seen on the cornea of both eyes.

33. STEREOPSIS
SUPPRESSION & DIPLOPIA
RETINAL CORRESPONDANCE
TO BE DONE WITH FULL OPTICAL
CORRECTION
TO BE DONE PRIOR TO ANY

34. Gross Stereoacuity
Top of Upper Wings:2000seconds
Bottom of Lower Wings:1150 sec
Tip of Abdomen:700 sec
Fine Stereoacuity
Circles
1-3:800-200sec
4-6:140-80 sec
7-9:60-40 sec
Animals
A row:400sec
B row:200sec
C row:100sec

35.  Graded from 15-480 arc sec
 8 plates; 480/240/120/60/30/15
 1ST 3 plates to check for presence of
stereopsis
 4 is SUPPRESSION TEST PLATE
 If a child see 2 circle ask for larger circle
 5,6,7for degree of steropsis
 Special Glasses Required
 Kept at distance of approx 30 cms
 Cost around 20,000!!!!!!!!!
 Checks NEAR STEROPSIS ONLY

36. FRISBY DAVIS DISTANCE TEST

37. Diplopia Test
Patient is asked to comment on
–Position, Brightness, Separation between images
STIMULATOR

38. NON SURGICAL
 OPTICAL (eyeglasses, contact lenses, prism lenses)
 Medical
 Vision therapy or Orthoptic Exercise
SURGICAL
 eye muscle surgery
Strabismus Management

42. What is the prescription aim?
Our purpose is best visual acuity in distance
versus binocular alignment
 Certainly ,we want to eliminate any amblyogenic factors by
using the optical correction and consider the binocular
status

44. Prescribing for Children
 In adults, the correction of refractive errors has one
measurable endpoint: the best corrected visual acuity.
 Prescribing visual correction for children often has two goals:
1- providing a focused retinal image
2- achieving the optimal balance between accommodation and
convergence.
Unequal clarity in vision represents an obstacle to fusion and can facilitate suppression.
Significant RE, especially astigmatism and anisometropia, need to be corrected.

45.  All patients in minus lenses should be seen within 3 to
4 weeks after starting the therapy.
 Minus lenses should be discontinued if esotropia
develops.
 There are studies that suggest that this treatment may
induce myopia

46. Occlusion
 Part time patching of the non-deviating eye for four to six hours
daily may convert an intermittent exotropia to a phoria.
 Initially the results are evaluated after 4 months of occlusion.
 If the angle of deviation is decreased the occlusion should be
continued and assessment made every 4 months until no
further change occurs.
 In case there is no improvement for 4 months, it is
discontinued

47. Various Non-Surgical Therapies for
Intermittent Exotropia
Corrective lenses for any significant RE
part time Alternate Occlusion
Minus lenses Therapy
Orthoptics (Including
Convergence exercises)
Therapeutic Base – in
prisms

48. Indications for Surgery
Once deterioration is
documented
Waiting until deterioration has
relentlessly progressed may reduce
the chance of obtaining an
excellent surgical outcome
So improving fusional states accompanied by
higher surgical success rate

50. Orthoptics
 Goal is give comfortable binocular vision
 used to combat suppression, amblyopia, ARC, enhance
fusional amplitude and improve stereopsis
 In successful case transform tropia to phoria but not
eliminate it

51. Precise measurement of; angle alpha, the objective and subjective
angle of deviation, abnormal retinal correspondence, vertical and
torsional deviations and the area and density of suppression

52. Convergence insufficiency
 Most effective treatment
 Converge on an approaching object such as pencil or a
light while red filter is placed over one eye
 Aware of physiologic diplopia of a distant object while
fixing on a target at near
 Training fusional convergence with base out prism or
major amblyoscope
 Base out prism used during reading and continue on
home with increasing power

53. Fusion training
 Training of fusion amplitude enable symptomatic
heterophoria patient more comfortable
 Done by amblyoscope / synoptophore or prism exercise
Orthoptic is aimed to awareness of physiologic diplopia in
heterophoria and diplopia in heterotropia. Once diplopia elicited
vergence control activated. Forcing suppressed area concurrently
with corresponding area of dominant eye. Stimulation of retina of
deviated eye by moving visual target on major amblyoscope back
and forth across suppression scotoma. Suppression cannot be
effectively eliminated by orthoptic
Antisuppression Training

54.  Exercise 01: Pencil Pushups
 Step 1
 Hold a pencil on front of you at arm's length. The
pencil should be vertical, with the tip of the
sharpened pencil at the top. The pencil should
be directly in front of your face, with the tip just
below eye level.
 Step 2
 Move the pencil slowly toward your face as you
concentrate and focus on the point. Soon
you'll notice that you see two pencils rather
than one. Stop.
 Step 3
 Look away from the pencil briefly to rest your
eyes. Focus on something across the room for
two or three seconds, and then look back at the
pencil point where you've stopped it close to
your face. Look at the pencil point carefully, and
to try to focus so that the double vision
disappears and you only see one pencil.

55.  EXERCISE 2 – DOT CARD

 Hold the dot card near your nose with the line vertical and facing away. Angle the far end
slightly up. Squeeze the card very gently to keep it rigid.
 Look at the far end spot, which should be single.
 Notice that the line doubles to give an upside down ‘V’ whilst looking at the spot.
 The idea is to try and look at each spot in turn and see it as a single spot. If your eyes are
converging correctly, the viewed dot will be seen singularly (but not necessarily clearly)
and the other dots and line will appear to form an X.
 Try and bring your eyes in, and eventually to see the near spot singly
 This should be done gradually. DO NOT try and pull your eyes in to see the near spot
first.
 Once you have reached the near spot and can maintain it as a single spot you will notice
the line is now in a ‘V’ pattern. Hold each spot for 20 seconds and repeat 4 times.

56. THANK YOU
FOR YOUR ATTENTION