Amblyopia is a reduction in best-corrected visual acuity due to abnormal visual development in early childhood. It has several subtypes including strabismic, anisometropic, and stimulus deprivation amblyopia. The pathophysiology involves defective central visual processing and impairment of visual development due to optical, physical, or ocular alignment defects during the critical period of visual development in early childhood. Treatment involves identifying and correcting the underlying cause, as well as therapies like patching or atropine drops to strengthen the amblyopic eye. Part-time patching for a few hours per day is usually sufficient for mild to moderate amblyopia.

1. Amblyopia
Adedayo Omobolanle Adio
Professor and Consultant Pediatric Ophthalmologist &
Strabismologist,
University of Port Harcourt teaching Hospital, Rivers state
September 22nd 2021

2. AAO- Pediatric Ophthalmology/ Strabismus Panel. Preferred Practice Pattern
Guidelines -Amblyopia. San Francisco CA: 2007
Amblyopia (ambly-dull + ops-vision)
Unilateral or bilateral reduction of
best-corrected visual acuity with no
attributable structural abnormality of
the eye or of the visual pathways.
Introduction

3. Snellen chart equivalents
Snellen
Decimal LogMAR
Feet Meters
20/20 6/6 1.00 0.00
20/30 6/9 0.67 0.18
20/40 6/12 0.50 0.30
20/60 6/18 0.33 0.48
20/80 6/24 0.25 0.60
20/100 6/30 0.20 0.70
20/160 6/48 0.13 0.90
20/200 6/60 0.10 1.00

4. Introduction
• Amblyopia : Quantified as:
• Best corrected visual acuity of ≤ 20/40 or
• ≥ 2 line difference in Best corrected visual acuity between the 2
eyes. 1
• Amblyopia- One of the common cause of reduced vision
in childhood.
• Prevalence- 2-5% in general population not affected by
gender
Flynn JT, Cassady JC. Current trends in amblyopia therapy. Ophthalmology 1978;85:428-450.
Oliver M. Nawrarzki: Part II. Amblyopia – prevalence and therapeutic results at different ages.Br J Ophthalmol
1971;55:467-471.

5. Subtypes….
• Strabismic,
• Anisometropic
• Ammetropic,
• Meridional amblyopia
• Stimulus Deprivation Amblyopia

6. Amblyopia - Pathophysiology
• Amblyopia develops as a result of defective central
visual processing.
• Optical,
• physical,
• or ocular alignment defect during early childhood
• Impairment of visual Development………….

7. Pathophysiology of Amblyopia
Pattern Stimulus Deprivation /
Optical Defocus
Abnormal Binocular Interaction

8. Summary of Involved Basis

9. Neuronal Basis of Amblyopia

10. The problems with amblyopia
• Reduced best-corrected VA,
• visual function deficits of the amblyopic eye,
including
• abnormal contour interaction
• Reduced contrast sensitivity,
• Positional uncertainty,
• Spatial distortion, Poor accommodation,
• Abnormal eye movements, and
• Suppression.

11. Public health consequences of
untreated amblyopia
• More likely to become visually disabled because
of an increased risk of their sound eye becoming
visually impaired, with their estimated lifetime
risk of visual impairment being at least 1.2%
• Vision loss in the sound eye, often caused by
trauma, can have a significant effect on quality
of life with many employed individuals no
longer being able to work because of inadequate
visual function.

12. • Although amblyopic eye VA can sometimes
improve in adults after vision loss of their sound
eye, most remain visually disabled.
• Furthermore, the presence of unilateral
amblyopia has a deleterious effect on
binocularity, including stereopsis.

13. • Because good VA in each eye and/or normal
stereoacuity are often prerequisite for careers in
the military, aviation, surgery, law enforcement,
firefighting, as well as obtaining a commercial
driver’s license,18 amblyopic individuals are
often precluded from participating in such
occupations.19

14. • Because of good vision in their non-amblyopic
(sound) eye, persons with unilateral amblyopia
typically do not complain of blurred or poor
vision under habitual binocular viewing
conditions;
• Recent studies have reported reduced reading
speed and compromised fine-motor skills even
with both eyes open.

15. Pathophysiology of amblyopia
Differentiation and organization of the visual
pathways is not complete at birth
Modification and development is required after
birth-affected by environmental factors and the
visual cortex-Macaque monkeys
Abnormal visual experience-visual
deprivation(media) can affect retino-geniculo-
cortical development
The primary visual cortex ceases to be a faithful
relay of signals The cells of LGB shrink
Hubel DH, Wiesel TN.Effects of visual deprivation on morphology and physiology of cells in the cats lateral
geniculate body.J Neurophysiol 1963; ;26:978-93
Bron A, Tripathi RC, Tripathi BJ,eds. Wolff,s Anatomy of the eye and orbit.8th ed.London:Chapman & Hall ;1997 :551
594

16. Pathophysiology of amblyopia
In squint –causes abnormal input to the striate
cortex by preventing synchronous firing provided
by presenting simultaneous correlated images at
the foveae
-optical defocus in the deviated eye-the better eye
therefore chooses the clearer image and focuses
Striate cortex layer 4C
Booth R, Fulton A. Amblopia.In: Albert D, Jakobiec F. eds. Principles and Practice of Ophthalmology.2nd ed.
Philadelphia: Saunders;2000:4340-4354
Shan Y, Moster ML, Roemer RA et al. Abnormal function of the parvocellular visual system in anisometropic
amblyopia. J Pediatr Ophthalmol Strabismus. 2000;37:73-78..

17. Pathophysiology of amblyopia
In anisometropia-develops later than in strabismic
A
-As the visual system develops greater sensitivity
with time the bilateral blur lessens-not as severe
The critical period requires a prolonged period of
unilateral blur therefore it has a later onset
Meridional amblyopia-develops typically age 3y
Booth R, Fulton A. Amblopia.In: Albert D, Jakobiec F. eds.Principles and Practice of Ophthalmology.2nd ed.
Philadelphia: Saunders;2000:4340-4354
Shan Y, Moster ML, Roemer RA et al. Abnormal function of the parvocellular visual system in anisometropic
amblyopia. J pediatr Ophthalmol Strabismus. 2000;37:73-78.

18. Critical period
If the abnormal visual experience is sorted out
before the end of the critical period the process
reverses
In humans -4m
Peaks by 2y
Already begins to decline by age 4y and finally
ceases by age 9y
Dadeya S, Kamlesh, Shibal F.The effect of anisometropia on binocular visual function. Indian J Ophthalmol.
2001;49(4):261-3.
Hoyt CS . The long term visual effects of short term binocular occlusion of at –risk neonates.Arch Ophthalmol
1980;98:1967

19. To make a diagnosis
Confirm decreased vision-check vision
Exclude refractive error by doing a good
cycloplegic refraction-1% Cyclopentolate 2x over
30 mins or Atropine ointment bd for 3 days
Complete eye examination
Dadeya S, Kamlesh, Shibal F.The effect of anisometropia on binocular visual function. Indian J Ophthalmol.
2001;49(4):261-3.
Hoyt CS . The long term visual effects of short term binocular occlusion of at –risk neonates.Arch Ophthalmol
1980;98:1967

22. Cerebral Cortex
• Primary Visual Cortex , V1 , Broadman’s area 17
• Normally inputs from the ocular dominance
columns are equally divided between the 2 eyes
.
• The deprived eye shows a marked shrinkage of
its input stripes (ocular dominance columns) and
a corresponding expansion of the nondeprived
eye.

23. Amblyopia: Evaluation
 All components of the comprehensive pediatric medical eye
evaluation
 Common clinical manifestations of amblyopia
 Addition of, and special attention to, those factors that
specifically bear upon the diagnosis, course, and treatment
of amblyopia.

24. Evaluation of a patient
with Amblyopia
• Fixation preference:
Alternating Fixation Fixation preference for OS

25. Fixation Behaviour

26. Fixation
Two types-monocular and binocular
In monocular, check whether the patient is fixing
with the macular and the quality of fixation.
Occlude each eye separately and use the
smallest target possible for the child
3 things-quality(good , fair ,poor) location(Central
or
Eccentric) and duration(maintained vs sporadic)
If Ok=C=Central S=Steady M=Maintained or F&F
If eccentric=VA is <20/200

27. Eccentric Fixation
Bangerter’s Classification

28. mblyopia: Management Goals
• Identify and treat the etiology of the
amblyopia.
• Optimize visual acuity.
• Optimize binocular function.

29. Amblyopia – Therapy
• Correction of the underlying etiology…
Appropriate Refractive correction
Removal of the underlying cause of stimulus
deprivation (cataract , ptosis, corneal opacity )
Strabismus surgery
 Specific Therapy for Amblyopia….
 Occlusion/ Penalization

31. What Glasses To Prescribe ??
• Prescribing Glasses at different ages,
• With or without strabismus ……..

32. Refractive error determination
• based on a cycloplegic refraction using
cyclopentolate.
• Full correction of astigmatism, myopia, and
anisometropia is prescribed with the goal of
providing equally clear retinal images.
• Hyperopia is either fully corrected (e.g., in cases of
esotropia) or undercorrected (e.g., in cases without
esotropia) by no more than +1.50 D spherical
equivalent (SE), with any reduction in plus sphere
reduced symmetrically in the two eyes.

33. > 2.00
 2.50
 3.00
Astigmatism‡
> +1.50
> +2.00
> +3.00
Hyperopia with esotropia†
 +4.50
 +5.00
 +6.00
Hyperopia (no manifest
deviation)*
 –3.00
 –4.00
 –5.00
Myopia
Isometropia
(similar refractive error in both eyes)
Age 2–3 years
Age 1–2 years
Age 0–1 year
Diopters
Condition
TABLE 3Guidelines for Prescribing Eyeglasses for Young Children
Pediatric Eye Evaluation Preferred Practice Pattern™ 2002
* May reduce the amount by up to +2.00 D, or if the cycloplegic prescription is  +7.00 D may reduce by up to +3.00 D.
† Give the full cycloplegic prescription. If  +3.00 D, may reduce by +0.50 D.

34.  2.00
 2.00
 2.50
Astigmatism‡
 +1.50
 +2.00
 +2.50
Hyperopia
 –2.00
 –2.50
 –2.50
Myopia
Anisometropia
Note: These values were generated by consensus and are based solely on professional experience and clinical impressions, because
there are no scientifically rigorous published data for guidance. The exact values are unknown and may differ among age groups; they
are presented as general guidelines.
* May reduce the amount by up to +2.00 D, or if the cycloplegic prescription is  +7.00 D may reduce by up to +3.00 D.
† Give the full cycloplegic prescription. If  +3.00 D, may reduce by +0.50 D.
‡ Any oblique astigmatism (defined as  15 from the 90 or 180 axis) > 1 D should be considered for treatment.
Age 2–3 years
Age 1–2 years
Age 0–1 year
Diopters
Condition
TABLE 3Guidelines for Prescribing Eyeglasses for Young Children
Pediatric Eye Evaluation Preferred Practice Pattern™ 2002

35. Effect of spectacle wear on kids
and parents
• The initial and replacement costs of spectacles
• Variable cooperation with wear time
• Perceived cultural stigmata of wearing glasses are
obstacles to treatment success.
• PEDIG studies have shown that a large percentage (77%)
of children with anisometropic amblyopia improve 2 or
more lines of vision within 15 weeks of wearing glasses.
• Children with less anisometropia and better baseline
visual acuity tend to show the most improvement with
spectacles alone.
• Additional treatment with patching or atropine may be
necessary if VA improvement with spectacles alone is
incomplete

36. Treatment
Principal
cause
Patching
Penalisation
Persistence
Passion

37. Patching/Occlusion therapy
• Gold standard for amblyopia
• Patch the better seeing-eye
• Forcing the amblyopic eye to work
Penalization:
• Instillation of atropine eye drops or
• Provide a high power glasses…
• To make blurred vision in good eye

38. • Over- or underutilization of treatment
modalities often leads to poor quality health
care.
• Prior to PEDIG trials on the duration of daily
patching for amblyopia, full-time patching
was commonly recommended.
• Social stigmata surrounding patching and
the associated difficulties of daily life lead to
poor compliance and significant family
dissatisfaction with treatment.

39. Moderate amblyopia (20/40-
20/100)
• 2 hours/day for moderate amblyopia and
counsel parents that 62% of patients
achieve either 20/30 visual acuity or at least
3 lines of improvement from baseline within
about 4 months of treatment.
• Similarly, 6 hours/day same as full-time
patching for severe amblyopia (20/100-
20/400) with an average of 4.1 lines of
vision improvement.

40. Best time to start
• Before the patient is 5 years old will yield
greater improvement and stability of visual
acuity compared with treatment initiated in
children 7 to 17 years old.
• No studies are available to assess the
effectiveness of patching 2 hours/day
versus 6 hours/day for severe amblyopia.

41. • Patching has been found to be safe, as it
does not impact the refractive error of the
sound eye.

42. Patches .….

43. Occlusion Therapy
• Full time Patching
• Patching during all
waking hours
• Conventional
• Reported success rate of
88%
• Part Time Patching
• Patch for Limited no. of
waking hours
• Easily accepted by
children and parents
• Success rates
equitable…

44. Part Time Patching…
• Possible to achieve:
• Patching of the eye only during work at home and even
in play hours for moderate to severe amblyopia.
• Lesser Emotional Stress….
• Lesser Peer Pressure
• Greater Compliance……

45. Occlusion Therapy
• Part time Patching Guidelines:
• Mild Amblyopia ( VA : 20/40-20/60): 2 hours/d
• Moderate Amblyopia ( VA: 20/60- 20/100): 3 to 4 hours/d
• Severe Amblyopia ( VA < 20/100): 6 hours/d

46. Penalization/atropine therapy
For moderate amblyopia is equally effective and enduring
as patching
Weekend-only versus daily atropine penalization showed
equal improvement of moderate and severe amblyopia
Reduced atropine administration frequency will likely lead
to improved compliance and parental satisfaction with
treatment.

47. Other considerations
• Addition of a plano lens to the sound eye
treated with atropine has not been shown to
be effective.
• Quality of life has been found to be better
with atropine penalization compared to
patching and can help the physician tailor the
best treatment course for the child based on
his or her individual needs

48. Penalization
• Penalization:
• Optical penalization
• Pharmacological penalization
• Optical Penalization:
Full time or part time.
Atropine eye drops once/ Twice a Week

49. Refractory Cases…
Combined Occlusion and Atropine Therapy…..
1.Repka MX, Kraker RT, Beck RW, et al., Pediatric Eye Disease Investigator
Group. Treatment of severe amblyopia with weekend atropine: results from 2
randomized clinical trials. J AAPOS. 2009;13(3):258–263.

50. Guidelines for Treatment.....
• LACUNA IN KNOWLEDGE
• 1997, PEDIG
• Pediatric Eye Disease Investigator Group
• Amblyopia – most common cause of
monocular visual impairment
• ATS – Amblyopia Treatment Study

51. The Pediatric Eye Disease
Investigator Group (PEDIG)
• is a clinical network of pediatric optometrists and
ophthalmologists funded by the National Eye Institute
to conduct clinical research studies related to pediatric
eye conditions.
• PEDIG studies have focused on evaluating the
comparative effectiveness of different amblyopia
treatment regimens for children and adolescents.
• Amblyopia Treatment Studies (ATS), and their results
have dramatically changed amblyopia clinical practice
patterns for many eye care providers..

52. PEDIG – Amblyopia treatment
studies
Study Objective Results
ATS 1
( 419 patients,
VA 20/40 to 20/100 )
Atropine (daily) vs
Patching (6hrs)
No significant
difference in the visual
acuity ,
Faster with patching
ATS 2A ( 175 patients,
VA 20/100 to 20/400)
6 hrs patching vs Full
Time patching
Similar improvement
ATS 2B ( 189 patients, VA
20/40 to 20/100 )
2 hrs vs 6 hrs patching No difference
ATS 2C ( 156 children , < 8
years of age )
Risk of recurrence 25 % risk, more likely
if it was not tapered

53. Amblyopia treatment in
children
aged 7 to 17 years (ATS 3)
• 507 patients
• VA : 20/40 to 20/400
• Methods
– Optimal optical correction
– Randomisation to treatment group (2-6 hours per day of
prescribed patching combined with near visual activities
for all patients plus atropine sulphate for children aged
7 to 12 years) or optical correction group

54. Conclusions
7-12 years
Prior Treatment
+/-
Further Treatment Works
>13 Years
Prior Treatment
Unlikely to Work….

55. Near activities
• Results
– After 4 weeks, greater improvement in near visual
activities group
– Children instructed, spent more time performing those
near activities compared to children not instructed

56. • Educating the patients about :
• The need and purpose of patching ,
• Intolerance of the child towards
patching the better eye
• Role of Near Activities
• Is equally important
Parental Counselling
• Holmes JM, Beck RW, Kraker RT, et al., Pediatric Eye Disease Investigator Group. Impact of patching
and atropine treatment on the child and family in the amblyopia treatment study. Arch Ophthalmol.
2003;121(11):1625–1632.

57. Follow up
Frequency:
• Risk of Occlusion Amblyopia
• Examine the patient ‘Two- Four week for Every year of
age’
• 2 year old child: every 4-8 weeks,
• If no occlusion amblyopia, follow –up period can be
doubled

58. BCVA
Change
Compliance/
Emotional
Impact
Adverse
Events
Misalignment
Cycloplegic
Refraction

59. When To stop Amblyopia
Therapy
• Visual acuity becomes
equal in both eyes
• True alternation of fixation
• Maintainence patching :
Upto 11 years
• If no improvement in
vision upto 3 – 6 months
of starting treatment.

60. Recurrence
• Recurrence of amblyopia is much more likely
to occur if treatment is abruptly suspended
rather than slowly tapered prior to
discontinuation.
• Parents should be counselled that
approximately 20% of children will have
regression after amblyopia treatment cessation
• Surveillance for amblyopia recurrence is
necessary.

61. Other Modalities Of Treatment
• Pleoptics
• CAM Stimulator
• Vision Stimulation
• Pharmacotherapy
• Refractive Surgery
• Accupunture
• Magnetotherapy….

62. Levo-Dopa
• Improvement in visual acuity more than in controls
• Improvement in contrast sensitivity
• Improvement in visual acuity is maintained for a longer
time
• Possible side effects….
• Safe in dosage : Levodopa 0.50 mg/ kg B wt tid;
Carbidopa 1.5 mg/kg B wt tid
Adjunctive role to patching / penalization

63. Refractive Surgery
• Objectives:
• Reduce the refractive
error,
• Reduce anisometropia
and anisokonia
• Treat Anisometropic
Amblyopia

64. Refractive Surgery Outcomes
• Daoud YJ, Hutchinson A, Wallace DK. Refractive surgery in children:
treatment options, outcomes, and controversies. Am J Ophthalmol.
2009 Apr;147(4):573-582.
• Tychsen L. Refractive surgery for children: excimer laser, phakic
intraocular lens, and clear lens extraction. Curr Opin Ophthalmol.
2008 Jul;19(4):342-8.
• Paysse EA, Coats DK, Hussein MA et al. Long-term outcomes of
photorefractive keratectomy for anisometropic amblyopia in children.
Ophthalmology. 2006 Feb;113(2):169-76.
• Roszkowska AM, Biondi S, Chisari G et al. Visual outcome after
excimer laser refractive surgery in adult patients with amblyopia. Eur
J Ophthalmol. 2006 Mar-Apr;16(2):214-8.

65. Refractive Surgery - Conclusions
Positives Negatives

67. -Follow the theory that amblyopia is a binocular
process and treatment should take into account
both eyes.
Binocular visual stimulation through the use of
dichoptic glasses while playing video games is the
newest treatment regimen under investigation
New treatment modalities-under
investigation
• Hess RF, Mansouri B, Thompson B. A new binocular approach to the treatment of amblyopia in adults
well beyond the critical period of visual development. Restor Neurol Neurosci. 2010;28:793–802.
•

68. The ATS 18
• A non-inferiority study will compare the
effectiveness of 1 hour/day of binocular
game play with 2 hours/day of patching in
children 5 to 13 years of age.
• A superiority study will compare the
effectiveness of 1 hour/day of binocular
game play with 2 hours/day of patching in
patients 13 to 17 years of age

69. Clinical implications -patching
• Full-time patching is not always needed for a
successful treatment outcome.
• Prescribing lesser amounts of patching may
promote better overall compliance with
treatment.
• Some children with severe amblyopia will
respond to as little as 2 hours of patching.
• In young children, using an adhesive patch
should be strongly considered so that peeking is
less likely to occur.
• Mainstay of treatment

70. Conclusions-atropine
• More acceptable to parents than patching-best for moderate
amblyopia
• Atropine Penalisation is equally effective though slower
initially
• Treatment effect did not differ by age, cause of amblyopia,
or depth of amblyopia
• Weekend atropine equally effective
• If you also use plano lenses on sound eye-better VA
achieved than atropine only
• A switch in near fixation preference from the atropinized
sound eye to the amblyopic eye was not observed in a
number of children with significant amblyopic eye VA

71. Issues to note with atropine
• Reverse amblyopia
• Systemic side effects-mouth driness,
flushing, fever,confusion, irritability etc.
change to 5% homatropine if this occurs
• Consider for patching failures
• Instill before child wakes up
• Twice weekly ok
• Wear wide brimmed hat/sunglasses
• Store bottle securely

72. Amblyopia in older children
• The authors think that it is unlikely that the
difference in treatment response between
children 7 to 12 and 13 to 17 years was because
of a difference in visual plasticity.
• The authors hypothesize that the lesser treatment
effect in children 13 to 17 years might be
because it was more difficult for them to comply
with 2 to 6 hours of daily patching with their
overscheduled lives and/or they were not
prescribed atropine.

73. • Don’t withhold treatment for 13-17 y old

74. Can Amblyopia be prevented ?
• Dedicated pediatric ophthalmology units
• Teamwork comprising of
• neonatologists,
• general ophthalmologists and
• pediatric ophthalmologists
• Early Detection and management of predisposing factors

75. Comparing historical vs Current evidenced based
approaches
Of amblyopia treatment
Mainstay of amblyopia
treatment
Patching Optimal refractive
correction
Timing of refractive
correction+
occlusion(patching or
atropine
Simultaneous Occlusion prescribed after
gains from optical
treatment effect
Patching dosage for
moderate A
Generally, the more the
better(5-6h)
Start with 2h, increase if
required
Patching dosage for severe
A
Full time or most waking
hours
Start with 6h, 2 h effective
in some cases
Atropine penalization use Patching failures only 1st line as alternative to
patching or for patching
failures
Atropine penalization
guidelines
Amblyopia severity Only for moderate A Both moderate & severe
cases
Age of child Only in young kids Both young and old

76. My teachers
Ramesha Kekunnaya Virender Sachdeva Preeti-Patil Chaablani GangaPrasad
Amula

77. Thanks for listening…