This presentation designed for postgraduate ophthalmologist

1. Amblyopia
Abdelmonem M. Hamed, MD
Professor of Ophthalmology Benha College of Medicine
Fellow of Baylor College, USA

2. • Definition:
– Unilateral or bilateral reduction of the best
corrected VA that can not be attributed to the
effect of any structural abnormality of the eye.
– Etiology:
– any cause of abnormal visual experience early
in life like squint, refractive error, etc…
• amblyopia
– affects the central vision
– the peripheral visual field remains normal
Amblyopia

3. • Neurological mechanism:
– not completely understood
– may be (proven in animal models)
• abnormality of neurons in LG Nucleus
• functional deficiency of cells of 1ry visual cortex
• crowding phenomenon:
– may be due to large neurons of the receptive
neurological field
– difficult recognition of the snellens letters if
they are closely surrounded by similar forms
Amblyopia

4. • Types of amblyopia:
– strabismic
– anisometropic
– isoametropic
– deprivation (amblyopia ex anopsia)
Amblyopia

5. • strabismic amblyopia
– the most common cause
– occur in the deviating eye
– mechanism
• competitive interaction between neurons carrying the
nonfusible input from the 2 eyes
domination of the cortical centers by the fixating
eye
reduced responsiveness of the non fixating eye’s
input
Amblyopia

6. • Anisometropic amblyopia
– 2nd in frequency
– due to unequal refraction in 2 eyes…..one retinal image is
defocused
– mechanism: the same as in strabismic amblyopia
– how much anisometropia required to cause amblyopia:
• hypermetropia from 1-2 D…….mild amblyopia
• astigmatism from 1-2 D…….mild amblyopia
• myopia > -6 D ………sever amblyopia
• myopia < -3 D usually does cause amblyopia
Amblyopia

7. • Isoametropic amblyopia
– large, equal, uncorrected visual acuity in both
eyes…..mild bilateral amblyopia
– how much bilateral refractive error required to induce
amblyopia
• hyperopia > + 5 D
• myopia > -10 D
• cylinder ??? May be > 3 D
Amblyopia

8. Amblyopia
• Deprivation amblyopia (disuse amblyopia) (amblyopia
ex anopsia)
– due to congenital or early acquired media opacity
– the least common type of amblyopia, BUT
– the most damaging and difficult to treat form
– in general, congenital cataract that are dense and occupy the
central 3mm or more of the lens must be considered capable
of causing sever amblyopia
–

9. Amblyopia
• Deprivation amblyopia
– any lens opacities acquired during childhood (up to age
8-10) can be almost harmful
– smaller polar cataract; around which retinoscopy can be
readily performed, and lammellar cataracts; around
which a reasonably good view of the fundus can be
obtained, may:
– cause mild to moderate amblyopia, or
• have no effect on visual development
– occlusion amblyopia is a form of deprivation amblyopia
caused by excessive patching

10. Amblyopia
• Eccentric fixation
– use of a particular nonfoveal region of the retina
for monocular viewing by an amblyopic eye
– detection
• major degrees
» noncentral position of corneal reflex
» VA: 6/60 or worse
• minor
» needs special tests such as Visuscopy, Haidinger’s
brushes or Maxwell's spot
» VA: mild acuity loss

11. • Cataract
– removal of cataract must be during the 1st 2-3
months of life
– in symmetric cataract, the interval between the
operation on the 1st and 2nd eyes, should be
not more than 2 week
– traumatic cataract in children 8-10 years old,
should be removed in few weeks
Treatment of amblyopia

12. Treatment of amblyopia
• Optical correction
– Rule: full correction
under cycloplegia

13. Treatment of amblyopia
• Occlusion
– full time: total occlusion of the
better eye is the most powerful
means of treating amblyopia
By
» adhesive patch
(recommended)
» spectacle mounted occluder
(take care of child peeking)

14. Treatment of amblyopia
• Occlusion
– part time:
» several days of patching
alternating W several days
of no patching
» daily patching for several
hours
» keep the child visually
active. How? No specific
visual exercises

15. Treatment of amblyopia
• Penalization of the better eye
» to make the better eye image
inferior to the amblyopic eye
» instill atropine ointment 1%,
once daily, in the better eye
» ± echothiophate iodide 1/8 %
may be administered in
amblyopic eye to potentiate
the near vision

16. Treatment of amblyopia