amblyopia lazy eye

1. AMBLYOPIA
SIVA TEJA CHALLA

2. AMBLYOPIA
• DEFINITION
• EPIDEMIOLOGY
• PATHOPHYSIOLOGY
• CLASSIFICATION AND TYPES
• CLINICAL FEATURES AND DIAGNOSIS
• TREATMENT MODALITIES.

3. DEFINITION
• U/L or less commonly B/L reduction in BCVA that
cannot be attributed directly to the affect of any
structural abnormality of the eye or the posterior
visual pathways
• M.C.C of dec vision in childhood
• For practical purposes defined as atleast 2 snellen
line difference b/w two eyes

4. EPIDEMIOLOGY
• In developed countries 1-5% of the population
• In india affects 1-4% of children
• Goel et al. found the incidence to be 0.7% in rural
schools than in urban schools 0.5%
• Onset is birth to 7 yrs of age
• SE Factors does not significantly influence the age of
presentation of amblyopia
• Earlier the onset greater the defecit

5. • Four times more frequent in premature children
• Six times more frequent in children with delayed
mile stones
• Smoking and use of dugs and alcohol during
pregnancy have been asso with risk of amblyopia

6. PATHOPHYSIOLOGY
Amblyogenic factors
Role of retina
Active cortical inhibition

7. Amblyogenic factors
VISUAL DEPRIVATION
monocular
Seen in strabismic ,
anisometropic, stimulus
deprivation amblyopia
Binocular
Seen in bilateral cataract,
ametropia and bilateral
high refractive errors
LIGHT DEPRIVATION.
Usually seen in children
with unilateral or bilateral
complete cataracts.
ABNORMAL
BINOCULAR
INTERACTION
-produces profound
amblyopia due to
competition amblyopia.
-seen in strabismic,
anisometropic and
unilateral stimulus
deprivation amblyopia.

8. RETINA IN THE DEVELOPMENT OF AMBLYOPIA
• Decreased sensitivity of foveal cones in amblyopia
• The reduced input from rods and cones in the
affected eye causes certain neurophysiologic
changes, transmitted to the CNS which triggers
amblyopia.

9. ACTIVE CORTICAL INHIBITION
1) A developmental defect of spatial visual
processing occurring in the visual pathway.
2) Poor transmission from the fovea, optic nerve to
the Striate Cortex of the affected eye.
3) LGB & Striate cortex develop abnormally.
4) Ganglion cells in foveal area are affected;
Shrinkage of LGB Nucleus & Striate cortical fibres in
the amblyopic eye.
5) Loss of binocularly driven cells in LGB & Striate
Cortex

11. CLASSIFICATION & TYPES
• Strabismic amblyopia.
• Stimulus deprivation or amblyopia of disuse.
• Anisometropic amblyopia.
• Meridional amblyopia.
• Isoametropic amblyopia .
• Amblyopia secondary to nystagmus.
• Idiopathic amblyopia.
• organic amblyopia.

13. Amblyopia
‘Organic Amblyopia’
Irreversible
Structural abnormal
Mac scar, Optic
atrophy
‘Functional
Amblyopia’
Reversible
(when t/t early)
•Strabismic
•Anisometric
•Visual Deprivation

14. STRABISMIC AMBLYOPIA
• M/C form of amblyopia
• A.K.A amblyopia of arrest
• Seen in unilateral constant squint who strongly
favour one eye for fixation.
• cortical suppression from deviating eye thought to
be due to inhibitory interactions from neurons
carrying non fusable images which cause visual
confusion
• Esotropia more likely to develop amblyopia as
compared to exotropia

15. • Does not develop in alternating or intermittent
strabismus as there are periods of normal binocular
interaction that preserve the integrity of visual
system
• Severity of amblyopia does not correlate with angle
of strabismus

16. STIMULUS DEPRIVATION AMBLYOPIA
• Amblyopia ex anopsia disuse amblyopia.
• Least common but most damaging.
• Cause when the visual axis is obstructed.
• Monocular congenital or traumatic cataract,
complete ptosis, corneal opacity & prolonged
patching of the normal eye for treatment of
amblyopia.
• Less than 6 yrs – severe amblyopia.
• After 6 yrs – less harmful .

17. • Visual loss resulting from unilateral deprivation is
worse than that produced by bilateral deprivation of
similar degree

18. ANISOMETROPIC AMBLYOPIA
• 2nd m.c.c of amblyopia
• develops when unequal refractive errors in the 2 eyes
causes the image on 1 retina to be chronically
defocused.
• Most patients with anisometropic amblyopia have
straight eyes and appear “normal,” so the only way to
identify these patients is through vision screening.
• Hypermetopic anisometropia is more
amblyogenic than myopic anisometropia

19. • The amount of anisometropia that can induce
amblyopia varies according to the type of refractive
error
• Amount of anisometropia
Hypermetropia > 2D
Myopia > 4D
Astigmatism > 1.25D
However unilateral high hyperopia or myopia (>6D)
causes severe amblyopia

21. MERIDIONAL AMBLYOPIA
• Resolution of eye is reduced in selective meridians
as a result of un corrected astigmatism
• Cylinder >1.5D is comsidered amblyogenic
• Doesn’t develop until first year of age

22. ISOMETROPIC AMBLYOPIA
• Bilateral amblyopia occurring in children with
bilateral uncorrected high refractive error.
Hyperopia > +5 D.
Myopia > -10 D.
astigmatism > 2D
Mechanism – effect of blurred retinal images alone

23. AMBLYOPIA SECONDARY TO NYSTAGMUS
• Difficult to establish ascertain whether nystagmus is
the cause or effect of amblyopia
• Bilateral

24. IDIOPATHIC AMBLYOPIA
• Occurring in apparently normal patients with a
negative history of strabismus & in the absence of
other amblyogenic factors.
• Mech- foveal suppression of amblyogenic eye d/t
transient amblyogenic factor during infancy

25. CLINICAL CHARACTERISTICS
• Decreased visual acuity
• Decreased stereoacity
• Fixation reflex
• Crowding phenomenon
• Effect of neutral density filter
• Contrast sensitivity
• Fixation pattern

26. VISUAL ACUITY
• Two line difference between amblyopic and normal eye
• For B/L amblyopia the VA should be less than 20/40 in each
eye
• But in children there will be difficulty in assesing VA
Infants-fixation preference
preverbal children-preferential looking test,OKN test,VEP
2-3 yrs- E charts,pictoral charts
>3 yrs-snellens charts,HOTV charts

28. PREFERENTIAL LOOKING TEST

29. STEREOACUITY
• Presence of amblyopia can be detected by defective
performance on various stereograms
• Two pencil test is a clinically useful test and can be
applied even when VA recording is unreliable or not
possible
• Can also be easured by titmus fly test,random dot
stereogram

32. FIXATION REFLEX
• useful tool to assess VA in children <5yrs of age
• Central steady and maintained (CSM) fixation implies good
VA
Affixation  <3/60
unsteady fixation  3/60 to 6/60
Central but not maintained 6/60 to 6/18
Central but strong preference for other eye  6/18 to 6/9
Alternate fixation  6/6

35. CROWDING PHENOMENON
• Amblyopia pts exhibit better VA for single optotypes
than for letters placed in a row
• Although not specific for amblyopia,it may be
pronounced in amblyopic eye compared to better eye
• Single line acuity improves more than line acuity
during treatment
• So it is important to record both single letter and line
visual acuity every time as it is prognostic indicator

36. • Vision testing with single optotypes is likely to over
estimate VA in pts with amblyopia
• More accurate assesment of mono ocular VA is
obtained with the presentation of line of optotypes
or single optotype with crowding bars that surround
the optotype being identified

37. NEUTRAL DENSITY FILTER
• A neutral density filter reduces overall luminance
without inducing a color change.
• Decreased luminance of the visual target results in
diminished central acuity in normal eyes.
• Decreased illumination of visual targets has less of an
effect on amblyopic eyes because they are not using
central acuity
• It was found that neutral filters profoundly reduce vision
in eyes with organic amblyopia whereas vision of eyes
with functional amblyopia was not reduced and
occasionally even slightly improved.
• Hence it can be used to differentiate the two.

39. CONTRAST SENSITIVITY
• Reduction in contrast
sensitivity more for
higher frequencies
• Improves during
amblyopia therapy and
useful to monitor the
progress
• Contrast threshold
becomes normal in
strabismic amblyopia
when luminance levels
were reduced, while the
deficit persists in
anisometropic
amblyopia
pelli robson contrast
sensitivity chart

40. FIXATION PATTERN
• Bangerter’s classification of fixation patterns in
amblyopia
I. Central fixation
II. Eccentric fixation (nonfoveolar)- common type
III. No fixation
• Patients with eccentric fixation appear to be looking to
the side,not directly at the fixation target. They have poor
smooth pursuits,so they do not accurately follow a
moving target.
• Can be tested in old coperative children by visuoscope

42. OTHER FEATURES
• VEP Reduction in amplitude and slightly
prolonged latency
• Afferent pupillary defect may be seen
• Normalisation of VA in dim light occasionally
• Occasionally latent nystagmus

43. CLINICAL EVALUATION & DIAGNOSIS
• Thorough clinical history
• Binocular red reflex test
• Binocularity/stereo acuity testig
• Evaluation of visual acuity and fixation pattern
• Binocular alingnment and ocular motility
• External examination
• Pupillary examinaion
• Thorough ocular examination including fundus examination.
• Cycloplegic retinoscopy/Refraction
• Neutral density filter and testing for crowding phenomenon.

45. TREATMENT MODALITIES
Treatment of amblyopia involves following steps:-
1) eliminate any obstacles to vision , such as cataract.
2) correct any significant error.
3) force use of the poorer eye by limiting use of the
better eye.

46. • Refractive correction
• Occlusion therapy
• Penalisation
• Drug therapy
• Pleoptics
• Cam stimulator
• Surgery to treat the cause of amblyopia

47. CATARACT REMOVAL
• Removal of congenital lens opacity- first 4 -6 week of life.
• If symmetrical b/l cases- interval b/w 1st & 2nd eye should
not be not more than 1-2 weeks.
• Developing severe traumatic cataract in children less than
6 yrs removed within few weeks of injury.

48. REFRACTIVE ERROR CORRECTION
• Improves VA in 25-33% of patients with anisometropic
amblyopia and also in strabismic amblyopia
• Cycloplegic refraction followed by adequate optical
correction
• ATS 5 concluded that amblyopia improved with optical
correction in 77% and resolved in 27%
• Chen et al (AJO 2007) concluded that penalisation and
occlusion is required only if the child doesn’t improve
with glasses for four months
• In general eye glasses are well tolerated by children
especially when there is improvement in visual function

50. OCCLUSION THERAPY
• Occlusion of the sound eye is the most effective
treatment for amblyopia treatment
• When fixation is central, simple & effective.
• When fixation is eccentric, <7yrs central fixation
will be recovered.
• Older the child harder to regain central fixation.
• Success rate 30-92%
• MOAprevent fixating eye taking part in act of
vision and removes inhibitory stimulus that arises
from stimulation from fixating eye

51. Types of occlusion
• Total or partial
• Conventional or inverse
• Full time or part time
• Patching is most commonly prescribed,however
contravercy exists concerning how much treatment
is necessary
• Most data on response according to daily dosage of
patching are retrospective and uncontrolled

52. TOTAL VS PARTIAL OCCLUSION
total partial
•All light is prevented from
entering eye.
•Employed in amblyopic eyes
with acuity less than 6/24
•Occlusion using elastoplast,
gauze pad, tape, doynes
rubber occluder.
•Does not cut off the total
light entering eye
•Degrades the vision of
normal eye such that
amblyopic eye gets better
vision and preference
•Occlusion using cellophane,
transparent nail polish, or a
higher plus lens.

53. CONVENTIONAL VS INVERSE OCCLUSION
Conventional Inverse
•Occlusion of sound eye •Occlusion of amblyopic
eye so that eccentric
fixation becomes less
fixed

54. FULL TIME VS PART TIME
Full time Part time
Removed only while going to
bed at night
Short time each day during
close work or watching
television.
Choice of initial Rx In relapses after Rx and also for
maintanence

55. Types of occluders
• Adhesive skin patches made of micropore
• Commercially available opticlude
• Spectacle occluder
• Contact lens occluder
OPAQUE CONTACT LENS

56. • Patches • Micropore tape with soft tissue paper
• Spectacle patch / frost glass • Doyne’s occluder

57. Paediatric eye disease investigator group(PEDIG) has
conducted several amblyopia treatment trials (amblyopia
treatment study or ATS) over the past several years. Results
have shown that
• Spectacles alone are powerful treatment for amblyopia;
patching is superior to spectacles
• Initiating fewer hours of prescribed patching seems to be
as effective as traditional treatment
• Patching is effective in older children particularly if they
have not been treated earlier
• Atropine is as effective as patching
• Weekend atropine is as effective as daily atropine

58. How much patching??
The amblyopia treatment study have helped to define
the role of full time patching vs part time patching
• In patients aged 3-7 years with severe amblyopia
(VA B/W 6/30 to 6/120) full time patching produced
similar effect to that of six hours patching per day
• In patients aged 3-7 years with moderate amblyopia
(VA better than 6/30) 2 hours patching produced
similar effect to that of six hours patching per day

59. Treatment of amblyopia in 7-17 yrs
• For 7-13 yrs age group 2-6 hours of patching can
improve VA only if previously treated
• For 13-17 yrs age group 2-6 hous of patching
improved VA even if not treated previously
• Long term results from these studies are still
pending

60. HOW TO GO ABOUT OCCLUSION
• Motivation of child and parents.
• Active vision exercises by amblyopic eye like dotting O’s
and encircling E’s in a newspaper, joining dots,reading
comics and story books.
• In case of vision improvement, occlusion is continued till
amblyopic eye has not only developed equal vision but
also equal preference of fixation.
• May take 3-6 months.
• If there is no improvement. Then treatment is stopped.
Also other causes to be ruled out.
• Maintainence treatment is continued atleast upto 9 yrs of
age with part time occlusion and exercises

61. Rx schedule for initial occlusion
Age in yrs Period of
occlusion(days)
Direct : inverse
Follow up after every
Upto 2 2 :1 15 days
3 3 : 1 15 days
4 4 : 1 1 month
5 5 : 1 1 month
6 & older 6 : 1 1 month

62. • Follow up-depending on age,severiy of amblyopia
and compliance
• To look for-VA, fixation pattern and occlusion
amblyopia
• When to stop occlusion
VA equals in both eyes
alternation of fixation
• When VA is stable patching may be decreased slowly
• Because amblyopia recurres in large no. of patients
maintanence therapy or tapering of therapy should
be strongly considered.

63. Disadvantages of occlusion
• Occlusion amblyopia
• Non compliance
• Psychological distress
• Appearance of constant deviation
• Allergic skin rash
• Diplopia
• Cosmetically inacceptable

64. Prognostic considerations
• Younger the age better the prognosis
• Type of amblyopia myopic anisometropia> hyperopic
anisometropia> strabismic amblyopia> stimulus
deprivation
• Pretreatment VA
• Type of occlusion
• Type of fixation
• Near exercises
• Patient compliance and parent education
• Presence of astigmatism
• Method of treatment termination
• Previous treatment
• Refractive correction

65. TREATMENT OF ANISOMETROPIC AMBLYOPIA

66. TREATMENT OF STRABISMIC AMBLYOPIA

67. PENALISATION
• Therapeutic technique performed by optically
defocussing the eye with better vision by using
cycloplegia or altering the eye glass lens
INDICATIONS
No compliance for occlusion.
Mild degrees of amblyopia.
Maintainence after occlusion.
Anisometropic amblyopia

68. • Advantages cheap,better compliance
• DisadvantagesS/E of drugs
risk of occlusion amblyopia
systemic absorption
• Unless penalisation decreases the VA of dominant
eye below the amblyopic eye this form of treatment
is not adviced

69. Methods of penalisation
a. Near penalization: fixing eye is atropinized &
fully corrected for distance, amblyopic eye is
overcorrected with +2 to +3D .
b. Distance penalization : fixing eye is atropinized
& overcorrected, amblyopic eye is fully corrected.
c. Total : fixing eye is atropinized & undercorrected
by 4 to 5 D, amblyopic eye is fully corrected.

70. PLEOPTICS
• Involves active stimulation of fovea to overcome
eccentric fixation & improves Va.
• The peripheral retina including the eccentrically
fixing area around the fovea is dazzled.
• After lights are turned off, fovea functions better
because the surrounding retinal area is in a state of
hypofunction
• ONLY INDICATION IS coperative and intelligent
child older than 6yrs having eccentric fixation

71. ORE PLEOTOPHORE

72. CAM STIMULATOR
• Slowly rotating high contrast square wave grating of
different spatial frequencies
• Principle – rotating gratings provide specific
stimulation for cortical neurons
• the visual improvement was found to be better in
emmetropes and hypermetropes than those in
strabismus amblyopia
• Not used these days

74. PHARMACOLOGICAL THERAPY
• LEVADOPA is the only most extensively studied
drug in western and Indian population
• Precursor of dopamine known to influence visual
system at retina and cortical level
• Advantages
Augments conventional occlusion
Speeds up recovery of visual functions
Improves compliance
Reduces cost and duration of treatment

75. • Catecholamine based medical treatment citicholine
has been demonstrated to improve VA in amblyopic
eyes

76. SURGERY
By reducing anisometropia refractive surgeries has
reported to
• Improve spectacle tolerance
• facilitate amblyopia thearpy
• Enhance binocular vision
Also used for children who has finished amblyopia
therapy and cannot comply with spectacles or contact
lens

77. Surgical therapy for strabismus generally should
occur after amblyopia is reversed.
• Disadvantages to surgical therapy prior to correction
of amblyopia include
 difficulty in telling if amblyopia is present because
there is no longer a strabismus to assess fixation
preference and higher potential to being lost to
follow-up, as the child cosmetically looks better.
 The improved cosmesis gives the parents a false
sense of security about the vision improving

78. RECURRENCE
• Chances are high until child is visually mature.
• Careful monitoring every month upto 1 year, every 2
months upto 2 years and 4- 6 months upto visual
maturity is required.
• Maintainence occlusion to be given

79. SCREENING
• AAO recommends screening by the age of 3 yrs and
thereafter every 2yrs
• Includes visual acuity, corneal reflex test, refraction,
fixation preference and stereo acuity
• AAP suggests that vision screening should begin at
birth and continue as a part of child regular medical
check up
• All new born infants should be screened in nursery
with the use of red reflex
• Infants at risk should undergo detailed evaluation

80. Severe amblyopia can be eliminated as a public health
problem
• The goal can be achieved by
 improvements in public awareness
 better screening protocols at the level of primary
health care provider
 full access to medical care for at risk patients

81. THANK YOU