amblyopia 2
TRANSCRIPT
By AMEERHAMZA S B6th term MBBS
Shimoga Institute of Medical SciencesShimoga
AMBLYOPIA
How we see?
We learn to see, like walking or talking Learning to see is a slow process At birth – vision is noisy, can not distinguish
targets Object tracking starts around 3 month old Hand-eye-body coordination starts after 3 month
old Depth perception appears after 5 month old Vision is well developed by two years old
Definition:
It refers to a partial reversible loss of vision in one or both eyes, for which no cause can be found by physical examination of eye(absence of any organic disease).
Pathogenesis
Amblyopia is an eye condition when the nerves that connect one of the eyes to the brain do not develop correctly during childhood. As a result, the person sends blurry or wrong images to their brain, which results in the brain ignoring the information and favoring the other eye. Patients are seen using one eye more or may have problems with depth perception.
TYPES
Strabismic Stimuslus deprivation
Anisometropic
Isoametropic
Strabismic amblyopia
Two eye moves in two direction
Brain cannot combine image from two eye into one
Double vision Brain starts to ignore
image from one eye Causes unilateral
amblyopia
Stimulus deprivation amblyopia
Congenital or traumatic cataract or corneal haziness
Occlude lights to reach the retina
No or distorted image formed on retina
No visual learning happens Both unilateral or bilateral
amblyopia can occur
Anisometropic amblyopia
Different focusing power in two eye
One eye gives clearer image than other
Brain starts to ignore the blurrier image
Causes unilateral amblyopia
Isoametroipc amblyoipa Is bilateral amblyopia occuring in
children with bilateral uncorrected high refractive error
Occurs in children eith uncorrected astigmatic refractive error
Meridional amblyoipa
Clinical features Visual acuity is decreasedCrowding phenomenon : visual
acuity is less when tested with multiple letter charts (eg.snellen’s chart)than single letter charts (eg.optotype).
Treatment
Younger the child , better is the prognosis.
Works best when child is under 3yrs of age.
1) Occlusion therapy : occlusion normal eye to force use of amblyopic eye
Before that procedure it should be ensured that
If any cataract…. is corrected. If any refractive error…is corrected. Upto 2 yrs it should be done in 2:1 i.e. 2
days occlusion in normal eye and one day in amblyopic eye.
At the age of 3… 3:1 At the age of 4….4:1
At the age of 5….5:1…..until the visual acuity develops fully
2) Penalization
i.e. blurring of vision of normal eye either by using
Atropine (Atropine penalization) orOver plus lenses in spectacles
(optical penalization)
3) Computerized vision therapy
It works on the form of operant conditioning(a form of psychological treatment)
Computerized Home Vision Therapy (CHTV) can prescribed as an alternative to occlusion therapy.
Other treatments• To re-establish foveal
fixation in young children
Pleoptic exercises
• Using levodopa/carbidopa as adjunct yo occlusion therapy
Pharmacologic manipulation
• Also suggested as an adjunct to occlusion therapy
Perceptual learning
Refernces
Comprehensive Opthalmology by A.K.Khurana ,6th Edition.