introduction , diagnosis and management

1. 1
Amblyopia: Introduction,
Diagnosis & Management
Dr Azmat Khan

2. 2
Amblyopia
( Amblyos– Dull, ops—vision)
“Defective visual acuity in one or both eyes,
which persists after correction of the
refractive error & removal of any pathological
obstacle to vision”.

3.  Unilateral or bilateral decrease of visual
acuity caused by form vision deprivation
and/or
 Abnormal binocular interaction for which
no organic cause can be detected
3

4. Mechanism
 Deprivation of form vision
 Abnormal binocular interaction
4

5. 5
Thus we can summarize……
 Potentially reversible unilateral or bilateral inhibition
of normal visual development secondary to abnormal
visual experience occurring during the critical period
of visual development.

6. Amblyopia on the basis of VA
1. A difference in the best-corrected visual acuity (BCVA)
between the two eyes of two or more lines in the
absence of any organic lesion that could result in
visual reduction.
2. A BCVA of less than 6/12 monocularly or bilaterally in
the absence of any organic lesion that could result in a
decrease in vision.
6

7. Amblyopia on the basis of
Severity
1. Mild = VA < 6/12 to > 6/18
2. Moderate = VA < 6/18 to > 6/36
3. Severe = VA < 6/36
7

8. Critical Period & Basic Information
Children are different:
 Developing cortical connections
 Window of opportunity for diagnosis and
treatment…just like with language development
 Newborns have poor vision at birth.
 Visual acuity reaches normal adult level by age
of three years.
 Vision remains plastic until the age of 12 years
8

9. Milestones
9
 30 weeks - Blink to light
 31 weeks - Pupils react
 2 to 3 weeks - Early fixation
 Horizontal gaze - Birth
 Vertical - 2 months
 Fixate - Birth to 3 months
 Follow - 3 months
 Color ? (3 months)
 Field – Adult-like 1 year

10.  There is a critical period for sensitivity in developing
amblyopia.
 Amblyopia develops only in the critical periods, when
neural plasticity makes the visual system vulnerable
to any abnormal experience, such as strabismus, a
blurred image or occlusion.
 Once this period is over, amblyopia does not
develop.
 The time necessary for amblyopia to occur during
critical period is shorter for stimulus deprivation than
for strabismus or anisometropia.
10

11. Normal Development of Vision
and Eye Movements
Fixation
Poor following
Intermittent strabismus frequently present
Visual acuity 6/120 to 6/180
BIRTH – Term

12. One Month
Horizontal following to midline
Improving alignment
Visual acuity 6/90

13. Two Months
Vertical following begins
Improving alignment
Visual acuity 6/60

14. Three Months
Good horizontal & vertical following
Normal alignment
Visual acuity 6/30
Accommodation begins
Binocularity detectable

15. Visual acuity 6/9–6/12
Binocularity well developed
Six Months

16. 8 to 12 Years?
End of sensitive period for amblyopia

17. Epidemiology & Significance of
Amblyopia
 Amblyopia is common, with prevalence estimates
of between 2 and 4%.
 It is the most frequently treated disorder in
paediatric ophthalmic and orthoptic practice.
 Amblyopia is usually unilateral.
 The commonest risk factors for amblyopia are
constant strabismus and asymmetrical refractive
errors.17

18.  Anisometropic and/or strabismic amblyopia account for
over 90 percent of all amblyopia.
 Isoametropic amblyopia is rare, accounting for only 1-2
percent of all refractive amblyopia.
 The exact prevalence of form deprivation amblyopia is
unclear, but it is also considered rare.
18

19.  Nearly all amblyopic visual loss is preventable or
reversible with timely detection and appropriate
intervention.
 Poor vision in one eye  loss of stereoacuity 
loss of job opportunities.
19

20. Risk Factors
 The risk of developing amblyopia is associated
with strabismus, significant refractive error, and
conditions that may cause form vision
deprivation by physically blocking or occluding
the visual axis of one or both eyes during the
sensitive period from birth to 6-8 years of age.
 Number of additional risk factors have been
identified:
20

21.  Prematurity
 Low birth weight
 Retinopathy of prematurity
 Cerebral palsy
 Mental retardation
 Family history of anisometropia, isoametropia, strabismus,
amblyopia, or congenital cataract
 Maternal smoking and the use of drugs or
alcohol are associated with increased risk for
amblyopia and strabismus.21

22. Description and Classification
of Amblyopia
 The classification of amblyopia is based on the
clinical conditions responsible for its development.
 This classification serves as a practical method for
identifying its etiology and applying appropriate
management strategies.
 Functional amblyopia occurs before 6-8 years of age
and is attributable to form deprivation, strabismus, or
anisometropia.
 Other forms of vision loss are sometimes incorrectly
classified as amblyopia:
22

23. Differential Diagnosis of Cases of Reduced
Visual Acuity
Functional amblyopia
causes
Psychogenic
causes
Structural/pathologic
al causes
1. Form deprivation:
 Congenital/traumatic cataract
 Early complete blepharoptosis
 Corneal opacity
 Hyphema
 Vitreous hemorrhage
 Uncontrolled occlusion therapy
 Uncontrolled penalization therapy
2. Constant unilateral strabismus
3. Amblyopiogenic uncorrected
refractive error:
 Anisometropia (spherical or
astigmatic)
 Isoametropia
4. Combined aniso-strabismus
1. Conversion
hysteria
2. Malingering
1. Coloboma
2. Myelinated retinal nerve
fibers
3. Retinopathy of
prematurity
4. Degenerative myopia
5. Hypoplastic optic nerve
6. Keratoconus
7. Opacities of the media
8. Macular, perimacular
chorioretinal scar
9. Macular pathology (e.g.,
Stargardt's disease)
10. Optic atrophy
11. Retrobulbar neuritis
12. Nystagmus (congenital,
latent, manifest latent23

24. Classification
1. Strabismus Amblyopia :Deviation
2. Anisometropia Amblyopia : Defocuss
1. Amblyopia Due to bilateral high
refractive error (isometropic) :Defocuss
2. Deprivation Amblyopia :Deviation24

25. 1.Strabismus Amblyopia
 The most common form of amblyopia
 Strabismic amblyopia is thought to result from
competitive or inhibitory interaction between neurons
carrying the nonfusible inputs from the tow eye.
 Which leads to domination of cortical vision centers
by the fixating eye and chronically reduced
responsiveness to the nonfixating eye input.
25

26. 2.Anisometropia Amblyopia
 Second in frequency
 It develops when unequal refractive error in the tow eyes
causes the image on the one retina to be chronically
defocused.
 This condition is thought to result:
 Partly from the direct effect of image blur in the
development of visual acuity.
 Partly from intraocular competition or inhibition
26

27. 2.Anisometropia Amblyopia
 Second in frequency
 It develops when unequal refractive error in the
tow eyes causes the image on the one retina to be
chronically defocused.
 This condition is thought to result:
 Partly from the direct effect of image blur in the
development of visual acuity.
 Partly from intraocular competition or inhibition
27

28.  Mild hyperopic or astigmatic anisometropia (1-2D) 
mild amblyopia
 Mild myopia anisometropia (less than -3D) usually
doesn't cause amblyopia
 unilateral high myopia (-6D)  sever amblyopia
visual loss.
 The eyes of a child with anisometropic amblyopia
look normaly to the family and primary care
physician.28

29. 3.Amblyopia Due to bilateral high
refractive error (isometropia)
 Isometropia amblyopia result from large,
approximately equal, uncorrected refractive error
in both eyes of a young child.
 Hyperopia exceeding 5D & myopia excess of 8
D  risk bilateral amblyopia.
Merdional amblyopia:
 Uncorrected bilateral astigmatism in early
childhood may result in loss of resoling ability
limited to chronically blurred meridians.
29

30. Potentially Amblyopiogenic Refractive Errors
Isoametropia:
Astigmatism
Hyperopia
Myopia
Diopters
>2.50 D
>5.00 D
>8.00 D
Anisometropia:
Astigmatism
Hyperopia
Myopia
>1.50 D
>1.00 D
>3.00 D
30

31. 4.Deprivation Amblyopia
 It is usually caused by congenital or early
acquired media opacity.
 This form of amblyopia is the least common but
most damaging and difficult to treat.
 In bilateral cases acuity can be 20/200 or worse.
 Occlusion amblyopia is a form of deprivation
caused by excessive therapeutic patching.
31

32. 4.Deprivation Amblyopia
 It is usually caused by congenital or early
acquired media opacity.
 This form of amblyopia is the least common but
most damaging and difficult to treat.
 In bilateral cases acuity can be 20/200 or worse.
 Occlusion amblyopia is a form of deprivation
caused by excessive therapeutic patching.
32

33. Diagnosis of Amblyopia
 The aim of examination is the comparison of
 The visual function of the two eyes (with crowding )
 The pt’s known or estimated vision with the norm for his
age
 Characteristics of vision alone cannot be used to
reliably differentiate amblyopia from other form of
visual loss.
 Refraction, fixation preference, neutral density filter,
Visuscope, Bruckners test & careful examination of
the fundi & media, may help in diagnosis.33

34.  The crowding phenomenon is typical for amblyopia but
not uniformly demonstrable.
 Afferent pupillary defect are Characteristic of optic nerve
disease but occasionally appear to be present with
amblyopia.
 Multiple assessment using a variety of tests or
performed on different occasions are sometime required
to make a final judgment concerning the presence and
severity of amblyopia.34

35. 1. Patient History:
 A review of the nature of the presenting problem
and chief complaint; visual, ocular, and
 General health history; developmental and family
history; and
 Use of medications.
35

36. 2. Ocular Examination:
a. Visual Acuity
b. Refraction
c. Monocular Fixation (visuoscopy & CSM)
d. Ocular Motor Deviation
 Through Hirschberg, Brückner, and ACT
 Determine whether strabismus is present, and when it is
 determine the frequency (constant or intermittent),
 The laterality (unilateral or alternating), and
 Magnitude of the deviation.
36

37. e. Sensorimotor Fusion:
 To evaluate sensorimotor fusion, specifically to determine
the presence of suppression and the level of stereopsis.
 The red lens, Worth's four dot, and random dot stereopsis
tests and major amblyscope.
f. Accommodation
g. Ocular motility
h. Ocular Health Assessment and Systemic Health Screening
37

38. Periodicity Table for Screening
Periodicity Schedule for Visual System Assessment in Infants and Children
Newborn to
6 months
6 months to
12 months
1 to <3 years 3 to < 5 years 5 years and
older
Ocular History x x X x x
External inspection
of lids and eyes
x x x x x
Red Reflex Testing x x x x x
Pupil examination x x x x
Ocular Motility
Assessment
x x x x
Instrument Based
Screening
x
+
x
+ *
Visual Acuity Fix
and follow
x x
Visual Acuity age-
appropriate
optotype
assessment
x
∆
x
∆
+: Bill using CPT 99174
∆: Bill using CPT 99173
*: If unable to test visual acuity monocularly with age appropriate linear optotypes, instrument-based screening is suggested.

39. Management of Amblyopia
39

40. When you are planning for Amblyopia
Treatment, consider the following factors:
 Age of the patient
 General health
 Initial visual acuity
 Specific type of Amblyopia
 Monocular fixation status
40

41. Treatment of Amblyopia involves the
following steps:
1. Eliminating (if possible) any obstacle to vision such
as a cataract
2. Correcting refractive error
3. Forcing use of the poorer eye by limiting use of the
better eye.
41

42. Cataract Removal
 Cataracts capable of producing Amblyopia require
surgery without unnecessary delay.
 Removal of significant congenital lens opacities
during the first 2-3 months of life is necessary for
optimal recovery of vision.
42

43.  In symmetrical bilateral cases, the interval between
operations on the first and second eyes should be no
more than 1 week.
 Acutely developing severe traumatic cataracts in
children younger than 6 years should be removed
within a few weeks of injury, if possible.
43

44. Methods of treatment:
 The basic principle underlying the restoration of
visual acuity, is to promote the use of the amblyopic
eye or eyes. This can be achieved by:
44

45. 1. Occlusion of the better eye
2. Cycloplegic drugs alone or in combination with
optical penalization
3. CAM visual stimulator
4. Pleoptic treatment, which was frequently used in
the past, has largely been discontinued now.
5. The use of systemic drugs is as yet only in the
experimental stage.
45

46. 1. OCCLUSION:
 Most commonly used method of treating Amblyopia.
 The rationale for using occlusion is that occluding
the better eye stimulates the amblyopic eye,
decreasing inhibition by the better eye.
 Occlusion enables the amblyopic eye to enhance
neural input to the visual cortex.
 It is also important in eliminating eccentric fixation.
 Both convenient and economical.
 Compliance with occlusion therapy for amblyopia
declines with increasing age.
46

47. Occlusion can be classified in several ways:
1. Type (direct, inverse, alternating)
2. Time (full-time, part-time, minimal)
3. Occluder (bandage, tie-on, spectacles, contact lenses,
pharmacologically induced).
Aims of occlusion are to:
 Equalize VA
 Achieve optimum VA
 Centralize fixation
47

48. Potential side effects of occlusion include:
 Occlusion Amblyopia (Amblyopia of the better eye) resulting
from indiscriminate or poorly supervised occlusion
 Dissociation of latent/intermittent deviation
 Intractable diplopia
 An increase in angle of deviation may occur on removal of
occlusion
 DVD; The eye may elevate further
 Poor compliance due to reduced vision during school and work
related visual tasks
 Cosmetic concerns
 Infection my be incubated by the patch
 Skin allergies and irritations with bandage-type occluders48

49. Occlusion should be continued until:
 Equal VA is achieved.
 The optimum VA is achieved
 There is no further increase in VA with full time total
occlusion.
49

50. 2. CYCLOPLEGIC DRUGS:
 The principle of the use of cycloplegia, in cases of
amblyopia is, to blur the vision of the better eye by
preventing accommodation & decreasing the depth
of focus, thus giving the amblyopic eye more
stimulus.
 A cycloplegic agent (usually atropine 1% or
homatropine ) once daily to the better eye.
 Cycloplegia is more effective for near.
 This form of treatment has recently been
demonstrated to be as effective as patching for mild
to moderate amblyopia.50

51. Advantages of these drugs are that:
 The patient can not cheat, as can occur with
occlusion.
 The child & parents often prefer it to occlusion.
 Little or no cosmetic problems
Disadvantages:
 Side effects of atropine
 VA may not be reduced enough, where there is
dense Amblyopia
 Atropine takes a period of 10-14 days to wear off51

52. 3. OPTICAL PENALIZATION:
 The principle is, the use of lenses to blur the VA of
the better eye & to augment the VA of the amblyopic
eye.
 Three types of penalization are used:
(1) Distance penalization….encourages the use of
Amblyopic eye for distance.
(Optimum correction for the Amblyopic eye—Add
+3.00 D to Better eye.)
52

53. (2)Near penalization………encourages the use of
Amblyopic eye for near.
(Full cycloplegic correction of the Better eye with
cycloplegia—Add +3.00 D to Amblyopic eye)
(3)Total penalization………encourages the use of
Amblyopic eye for both.
(Add a strong convex/concave lens to the better eye,
so that the Amblyopic eye sees best for both near &
distance
53

54.  Optical penalization and/or cycloplegia are RARELY the
first choice in the treatment of amblyopia, but they are
useful in supplementing or replacing occlusion.
is useful in children:
 with moderate or mild amblyopia, who do not cooperate
well with occlusion.
 in whom the level of VA has improved to some extent
with occlusion but has become static.
 in whom Nystagmus (latent) is present in addition to
amblyopia. (It is thought that occlusion may manifest the
latent component of the nystagmus.)

55. 4. OTHER THERAPIES
CAM VISUAL STIMULATOR:
 This apparatus was designed by Campbell,
Astrand and Mehdorn, in 1978, to treat amblyopia
by intense visual stimulation of Amblyopic eye for short
periods of time. Now rarely used.
PLEOPTIC TREATMENT:
 No more in use now-a-days.
 Was only suitable for older children & adults with
eccentric fixation.
 The apparatus used in this type of treatment was called
as Pleoptophore or projectoscope.

56. 5. SYSTEMIC DRUGS
 This therapy is still undergoing research & is not yet
a clinical option.
 Gottlob et al suggested that Levodopa (by
increasing systemic levels of the neuro-
transmitter—Dopamine), given orally produces an
increase in contrast sensitivity in an amblyopic eye
but does not induce changes in the non-amblyopic
eye.

57. British and Irish Orthoptic Association + US Pediatric
Eye Disease Investigator Group (PEDIG)
Recommendations:
 LogMAR tests of vision should be used where possible.
 Amblyopia treatment should only be instituted for
children whose vision falls below the normal range for
age
 Significant refractive errors should be corrected
 Improvement in acuity following refractive correction
should be allowed to plateau prior to treatment with
occlusion or atropine – this may take 16 – 22 weeks
57

58.  The choice of atropine orocclusion treatment should be
discussed with parents
 2 hours patching per day is effective for amblyopic
defects from 0.2 to 0.6 LogMAR(6/9 to 6/24 Snellen)
 6 hours patching per day is effective for acuities below
0.6 LogMAR (6/24 Snellen)
 Failure of acuity to improve with patching or atropine
treatment should prompt re-refraction and
reexamination of the fundus
58

59.  Deterioration of acuity during treatment in the
absence of an ocular cause should prompt
consideration of neuroimaging.
 The first follow up visit after initial treatment should
occur within 1 week for an infant and after interval
corresponding to 1 week per year of age for the
older child.
 Part time occlusion & optical degradation methods
allow for less frequent observation but regular follow
up is still critical
59

60.  Full-time, total occlusion is the method of choice in
nearly all patients of AMBLYOPIA WITH MANIFEST
STRABISMUS. It has the advantages that:
(a) abnormal binocular interaction is prevented &
(b) the inhibiting effect of the sound eye is eliminated.
 In severe amblyopia, full-time is more efficient than part-
time occlusion
 In moderate and mild amblyopia, the same improvement
in full and part-time patching
60

61.  Atropine has been shown to be as effective as patching
in the treatment of moderate amblyopia in children aged
from 3 to 7 years.
 Using atropine drops only once daily at weekends is as
effective as atropine used every day in the treatment of
moderate amblyopia.
 The greatest improvement is between 1-3 years of age
 Children between 8-11 years of age showed
improvement of visual acuity of 3 lines with part-time
occlusion, so amblyopia treatment at this age is
effective.

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