Amblyopia what u should know
Defective central visual processing, leading to reduced visual form sensation .
• In the first 6y of life, our capacity for high-level vision is vulnerable.
• Unequal foveal images from both eyes can lead to loss of vision in one/both eyes.
• With increasing age, this is harder to reverse and, by about 7–8y of age, is usually permanent.
• Amblyopia is related to interocular competitive disadvantage and vision quality preference
• Bilateral foveal image deprivation is less amblyogenic than uniocular.
✅ Common Causes of amblyopia:
No or reduced image
Image blurring from refractive error
Abnormal binocular interaction
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No or reduced image
• Stimulus-deprivation amblyopia
constant monocular occlusion for >1 wk/yr of life is very likely to lead to amblyopia in those <6 yrs .
• Most congenital cataracts, especially unilateral, are highly amblyogenic.
• Visual outcome is closely related to early removal but post-operative glaucoma risk decrease with age at surgery.
• Most operate at about 6 wks of age.
Image blurring from refractive error
• Neglected eyelid chalazion or infantile haemangiomas causing astigmatism
• Anisometropic amblyopia: unequal refractive power of the eyes .
• High risk with difference >2.5 D but may be significant with dideference as low as 1 D
• Ametropic amblyopia:
significant though symmetrical, refractive error >+5.00 DS or –10.00 D S causing bilateral amblyopia if uncorrected.
• Astigmatic/meridional amblyopia:
significant risk if >0.75 D cylinder
Abnormal binocular interaction
• Strabismic amblyopia: significant risk if one eye preferred for fixation and more common in esotropia than exotropia.
✅ Clinical features for Amblyopia:
• Reduced VA in the absence of an organic cause and despite correction of refractive error if present.
• Exaggeration of the crowding phenomenon (scores better with single optotypes).
• Tolerance of a neutral density filter.
In amblyopia, VA is reduced less by the addition of neutral density filters than in other causes of dropped VA( strabismic amblyopia > anisometropic amblyopia).
✅ Treatment for Amblyopia:
Critical period of visual development is up to 8y.
Younger ages, show more rapid response to treatment of amblyopia, but increased risk of inducing occlusion or reversal amblyopia in the covered eye.
Spectacle adaptation tried first and then either patching or atropine penalization.(Spectacle adaptation is the period of visual improvement which will occur from refractive correction alone )
Occlusion
• Adjust for age, acuity, and social factors.
• practice is very variable from center to another
• longer episodes (time/d) and longer treatment (weeks of patching) have been used for older patients and those with worse VA.
• No evidence that there is more benefits in patching for >4h/d, and this is used as an upper limit in some centres.
• CAM stimulator can be tried
• Colored video games can be encouraged during occlusion therapy
Penalization
• Atropinization is gaining an increased role.
• reduce the VA in the sound eye to about 6/18
• Maximally effective if the amblyopic eye has VA >6/18.
• most effective when there is a hypermetropic refractive error in the atropine-treated eye.
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Amblyopia – Causes, Symptoms, Treatments & More
Amblyopia what u should know
