Introduction, Assessment and Management of Amblyopia

Amblyopia Lazy Eye

1. AMBLYOPIA
PREPARED BY:
Anis Suzanna binti Mohamad
Optometrist

2. INTRODUCTION
What is amblyopia?
What are the types of amblyopia?
What causes of amblyopia?
Classification of amblyopia?
What are the sign and symptoms of
amblyopia?

3. What is amblyopia?
•“Lazy eye”
•A unilateral/bilateral condition
•The best corrected VA is poorer than 6/9 in
absence of the ocular media and fundus
anomalies or ocular disease.
•Prevalence:- occurs about 1 in 25 children develop some
degree of amblyopia.
•High risk of becoming blind.

4. Normal vision Amblyopia ( Loss of vision)

5. Reduction clarity of vision in amblyopic eye

6. How does it happen?

7. How does it happen?

8. What causes of amblyopia?
•There are four major causes of amblyopia which are:
Unequal/Poor visual acuity
Unequal refractive error (Anisometropia)
Bilateral equal high refractive errors (isoametropia)
Uncorrected moderate/high astigmatism
Strabismus/Misaligned Eyes
 Blockage or deprivation
 Toxic

9. Unequal/Poor visual acuity due to:
1) Unequal refractive error (Anisometropia)

10. Unequal/Poor visual acuity due to:
Uncorrected high myopiaUncorrected high hyperopia
2) Bilateral equal high refractive errors (isoametropia)
More than -6.00D to -9.00D More than +4.00D
Blurred image form onto the retina
because ray of light focused in front of
the retina.
Blurred image form onto the retina
because ray of light focused at the
back of retina.

11. Unequal/Poor visual acuity due to:
3) Uncorrected moderate/high astigmatism
Meridional amblyopia is a mild condition in which lines are seen less clearly
at some orientations than others after full refractive correction.

12. Unequal/Poor visual acuity due to:
3) Uncorrected moderate/high astigmatism
A Compound myopic
B Simple myopic
C Mixed astigmatism
D Simple hyperopic
E Compound hyperopic
Clinical types of astigmatism which can lead to meridonal astigmatism if it is not
corrected within plastic age.

13. Constant strabismus or an imbalance in the
positioning of the two eyes

14. Strabismic amblyopia

15. Blockage or deprivation
an opacity in the line of vision-e.g: cataract
Due to:-Congenital/traumatic cataract
-Congenital ptosis
-Congenital/traumatic corneal opacities.

16. Toxic
•Drugs -
chloramphenicol,
digoxin, ethambuto
l
•Tobacco- piped
smoker, excessive
smoker
•Alcohol- alcoholic
•Chemicals- Lead,
methanol
•Nutritional
disorders - such as
Strachan's
syndrome, lack of
vitamin A and zinc.
The optic nerve head in acquired optic
neuropathies

17. What are the types of amblyopia?
•The nature of amblyopia differs depending
on the cause:-
Refractive amblyopia
Anisometropic amblyopia
Meridonial amblyopia
Strabismic amblyopia
Visual deprivation amblyopia
Toxic amblyopia

18. Classification of amblyopia
Functional Amblyopia
•Not due to the diseases in
the eye
•unilateral/bilateral of the
eye
•Reversible
•Examples:
–Refractive amblyopia
–Anisometropic amblyopia
–Meridonial amblyopia
–Strabismic amblyopia
Structural/Pathological Amblyopia
•Due to lesion in the eye or
visual pathway
•unilateral/bilateral of the
eye
•Irreversible
•Examples:
–Visual deprivation
amblyopia
–Toxic amblyopia

19. Type Causes
Refractive amblyopia• Uncorrected isometropia
• Result :- A blurred image in both eyes.
Anisometropic amblyopia
(Second in frequency)
• Uncorrected anisometropia
• Result :- A blurred image in more ametropic
eye.
Meridonial amblyopia• uncorrected high astigmatism
• Result :- A blurred and distorted image in
unilateral or bilateral eyes.
Strabismic amblyopia
(most common)
• Constant strabismus
• Suppression in deviated eye
Functional Amblyopia

20. Structural/Pathological Amblyopia
Types Causes
Visual deprivation amblyopia • Opacities in ocular media or
structures
• Examples:- cataracts, cornea
opacities and cloudy vitreous in
infants.
Toxic amblyopia • Drugs, tobacco, alcohol, chemicals,
nutritional disorders.

21. What are the sign and symptoms of
amblyopia?
Symptoms
•No symptoms
•Blurred vision
•Reduced vision
•Reduced contrast
sensitivity
Signs
•No obvious sign, unless
severe abnormality is
present.
•Rubbing or squinting of
eyes
•Misaligning eyes
•Reduced VA
•Droopy eyelid

22. ASSESMENT

23. Assessment of deviation
–Compare magnitude at distance versus near
•Laterality
•Concomitancy
•frequency
–The test is
•Cover test
•Hirchberg test
–Uses pen torch
–Corneal reflexes
•Bruchner test
–Uses ophthalmoscope
–Observe the color and brightness of fundus reflexes and
compared

24. Hirschberg test
Bruckner test

25. Strategies in assessment of amblyopia
1. Visual Acuity (VA)
•Degree of amblyopia
•Crowding phenomena
–Normal Snellen Chart
•Line Acuity
–Single Letter Chart
•Single Letter Acuity
2. Neutral Density (ND) Filter
•Depth of amblyopia
•Differentiate between
organic amblyopia or
functional amblyopia

26. 1. Visual Acuity (VA)
–Amblyopes perform better when isolated letters
are used instead of full chart.
–Crowding effect
•Single letter acuity
–Infant
•Teller acuity chart
–Preschool-aged children
•Lea symbols, HOTV or broken wheel cards
–School-aged children
•Snellen chart or Log MAR chart

27. Visual Acuity Chart
Snellen Chart Single letter chart

28. Single Letter Acuity
Advantage
•Directly measures acuity
especially in children 3-6
years old.
Disadvantage
•Isolated letters can be
used, which may lead to
under estimated
amblyopia visual loss.
Solutions:
 Crowding bar may help alleviate this problem

29. Crowding effect
•Crowding bar, or contour interaction bars, allow the examiner to
test the crowding phenomenon with isolated optotype.
•Bar surrounding the optotype mimic the full of optotype to the
amblyopia child.
EO

30. Teller acuity chart
Lea symbol
HOTV

31. •In strabismic eye, mostly
it use other part of area
instead of fovea area
which consist rod.
•Image that form will
reduce in contrast.
•Hence, it also reduce the
visual acuity of the eye.

32. 2. Neutral Density (ND) Filter
•Strabismic amblyopia
–Better VA with ND filter
compared to the normal
eye
–The use of a neutral-
density (ND) filter in
front of the fixing eye
enhanced motion-in-
depth performance.
–exhibit residual
performance for motion
in depth, and it is
disparity based
•Anisometropic amblyopia
–Cannot be diagnosed
with neutral density filter
ND bar

33. Neutral Density (ND) Filter
Strabismic amblyopia Anisometropic amblyopia
VA increased with ND filter VA cannot be diagnosed with ND
filter

34. Contrast sensitivity test
–Detect functional differences between
strabismic and anisometropic amblyopes
–Strabismic amblyopes showed abnormalities
only in the high spatial frequency range
–Anisometropic amblyopes showed an
abnormal function both in the low and high
spatial frequency range

35. Contrast sensitivity test
Pelli-Robson contrast sensitivity chartFunctional Acuity Contrast Test (FACT)

36. The contrast sensitivity function
•A- normal contrast
sensitivity function
•B- mid to low contrast
sensitivity losses
•C- more severe
refractive errors or
severe amblyopia
•D- Mild refractive
error or mild
amblyopia
Examples of how the CSF is altered due
to refractive error or disease.
* The pivotal visual developmental study of Harwerth et al.

37. Eccentric fixation
–Fixate away from fovea
•In strabismic amblyopic eye
–Visuscopy
•Detect and assess eccentric fixation
•Explain decreased vision and lead to a more
accurate measurement of strabismus
•Grid center is temporal to foveal reflex(temporal
EF)
•Grid center is nasal to foveal reflex(nasal EF)
•Grid center is superior to foveal reflex(superior EF)
•Grid center is inferior to foveal reflex(inferior EF)

38. Eccentric Fixation

39. Binocularity/stereoacuity test
–Ambyopia reduced VA, it also has reduced stereopsis
–Stereo smile for infant
–Preschool random-dot stereogram or random-dot test for
preschool children
TNO test

40. Stereo smile
Random-dot stereogram

41. Refraction
–commonly can determine anisometropia
–Cycloplegic refraction
•Spasm the ciliary muscle to inactive the
accommodation by using drug
–Uses 1% cyclopentolate hydrochoride
–Usually more hyperopic or more astigmatic eye
for the amblyopic eye

42. External and internal ocular
examination of the eye
–Determine either it is visual deprivation
amblyopia or afferent pupillary defect are
characteristic of optic nerve disease but
occasionally appear to be present with
amblyopia
–To rule out ocular pathology
–These examination consist of assessment
•Physiological function
•Anatomical status

43. MANAGEMENT
Goal of treatment
Passive therapy
•Optical correction
•Occlusion
•Penalization
Active therapy
•CAM visual stimulator
•Intermittent photic stimulation (IPS)
•Pleoptics

44. GOAL OF TREATMENT :
to restore and improves visual acuity by two
strategies:
1. present CLEAR retinal image to the amblyopic eye
•eliminate causes of visual deprivation
•correcting visually important refractive errors
2. make the child use the amblyopic eye
•Recommended treatment should be based on
– patient’s age, visual acuity, compliance with previous
treatment & physical, social and psychological status

45. CHOICES OF TREATMENT
the choices of treatment of amblyopia are used alone or in
combination to achieve goal of treatment
1.Passive therapy:
The patient experiences a change in visual stimulation without any
conscious effort
i.Proper refractive correction
ii.Occlusion
iii.Penalization

46. Passive therapy:
i. Proper refractive correction
•PURPOSE:
–to provide sharp images and
providing OPTIMAL environment for
amblyopia therapy
•Give pt proper optical correction
alone
–Short period of time (6-8 weeks)
before initiation of other therapy

47. Passive therapy:
ii. Occlusion
•PURPOSE:
cover good eye to stimulate amblyopic eye
•Enable the amblyopic eye to enhance neural input to the visual cortex
•Decreasing inhibition better eye

48. •occlusion can be classified in several ways:
–Ways of patching
• adhesive patch
•spectacles occlude
•opaque contact lens
–Type
•direct occlusion: to stimulate amblyopic eye
•inverse occlusion: to weaken eccentric fixation
–Duration
•full time occlusion : for deprivational amblyopia
•part time occlusion : to help preserve fusion

49. •Ways of patching
–There are several ways of patching
–Excluding light and form:
•Adhesive patching
•Spectacle occlude
•Opaque contact lens
–Excluding form (ie: frosted glass)

50. - Partial patching form
•allow appreciation of form but diminish
acuity
–ie. Translucent materials (Bangerter foil)
–foil is cut to size and positioned on inner
lens surface
•or occlusion covering part of spectacles
–ie. Lower half of spectacles
–to promote use of the amblyopic eye for
near work

51. •Type
•Direct occlusion
•Patch the good eye
•stimulate amblyopic eye
•Indication for
•deprivation amblyopia
•anisometropic amblyopia

52. •Inverse occlusion
•For amblyopia associated with EF --> strabismic
amblyopia
•Patching the amblyopic eye
•To weaken eccentric fixation of amblyopic eye
•If children under 5 year old age
•direct full time occlusion may risk reverse amblyopia
•Do direct occlusion alternate with inverse occlusion
•Ie: for 3 years old children, may need 3 days direct and 1
day indirect occlusion consider 1 cycle and repeated
period of time

53. •Duration
–Based on binocular vision status, age,
performance need
•Full time occlusion
•24 hours a day/waking hours
•For children over 7 years over plastic age
•When there is no binocular vision
• strabismic amblyopia
–Alternate strabismus
–Constant strabismus
•Also anisometropic amblyopia with poor binocular
vision
•Shows more rapid development

54. •Part time occlusion
•For specific periods / prescribed activities
•When binocularity is present
•anisometropic amblyopia
•To help preserve fusion
•Prevent occluded eye become amblyopic if doing full time
occlusion
•Children under 4 years
•2 hours per day
•Prevent deprivation amblyopia in good eye

55. •Occlusion is maintained until there has
been no further improvement for the last 5-
6 weeks
•Frequent check are necessary to monitor
ocular health, binocular status and each
eye’s acuity

56. 1.Drug penalization
•1 gtt of 1% atropine instilled daily
• to good eye
•Provide sufficient blur to force the
child
•use amblyopic eye at near
•good eye at distance
1.Has cosmetic advantages and does
not totally disrupt binocular vision
•Effective method of treatment
•for mild to moderate amblyopia in
children
Active therapy:
Penalization

57. 2. Optical penalization
•Children who do not tolerate
patching
•Fog the good eye (non-
amblyopic eye) +3.00 D
•Amblyopic eye use for distance
and good eye use for near
•Not practically applicable
–Do near work most of time
compared to distance

58. 2. Active therapy:
•is designed to improve visual performance by the patient ‘s conscious
involvement in a sequence of a specific, controlled visual task that
provide feedback
i.CAM visual stimulator
ii.Intermittent photic stimulation
iii.Pleoptic

59. Active therapy:
i. CAM visual stimulator
•Treat amblyopia
–by intense visual stimulation for
short period of time
•Grating of different spatial frequency
are rotated in front of amblyopic
eye
•The good eye is occluded
•Method based on:
–cortical cell response to specific line
orientation and to certain spatial
frequency.
–Therefore rotation ensured that a
large range of cortical neurons are
stimulated

•Better for anisometropic amblyopia

60. Active therapy:
ii. Intermittent photic stimulation
•Mallet IPS unit
•described as the "heightened
response" to a visual stimulus
•The targets
–consisted of slides containing much
detail of varying type and angular
dimension
–viewed against a red flickering
background.
•Red slight stimulation at 4Hz
•detailed visual task for 20-30
minutes

61. 1. 2.
3.
4.

62. Active therapy:
iii. Pleoptics
•Purposes :
–To disrupt eccentric fixation in strabismic
amblyopia
•Apparatus based on ophthalmoscope
principle
•Euthyscope, projectoscope, pleutophore
•Exposed peripheral retina to a very bright
light while protecting the macular area
•Only suitable for children >7 years old
Euthyscope

63. Surgery
If amblyopia is due to:
• cataract  cataract surgery
•nonclearing vitreous opacities vitrectomy
•corneal opacities  corneal graft
•Blepharoptosis  tarsal tuck

64. THANK YOU