Underlying causes of deprivation amblyopia (cataract or ptosis) should be corrected before initiation of amblyopia treatment.
- however in strabismic amblyopia, treatment of amblyopia is carried out first followed by surgical treatment of strabismus if this is required, (since any subsequent eye muscle surgery will have no effect on the amblyopia) (1)
The aim of treatment is to force use of the poorer eye by occlusion of the better eye. Treatment can be divided into two phases:
- phase 1 – optical treatment
- regardless of the cause, more than 90% of children with amblyopia present with significant refractive error (myopia, hypermetropia, or astigmatism).
- first line treatment of amblyopia secondary to strabismus, anisometropia, or a mixture of mechanisms is optimum refraction (spectacles)
- if there is little or no improvement in vision after 12 weeks of full time spectacle wear and the original refractive correction seems accurate, patients should be started occlusion therapy
- pahse 2 - occlusion (patching) or atropine
- occlusion
- patches with an adhesive rim, stuck directly onto the periorbital skin (or onto spectacle lenses) of the eye with the better acuity, are the most commonly used
- the main aim is to deprive the good eye of visual input (with a patch) in order to force reliance on the amblyopic eye
- duration
- 3-6 hours of occlusion per day is recommended for majority of children with amblyopia
- although longer periods of patching are considered to be beneficial in gaining visual acuity, the US Pediatric Eye Disease Investigator Group (PEDIG) found no difference between two and six hours of occlusion treatment of moderate (20/40 to 20/80) amblyopia in 3 to 7 year old children
- in a further study of severe (20/100 to 20/400) amblyopia, no significant difference was found in the visual outcome in the amblyopic eye following full time (all but 1 hour per day) compared to 6 hours patching per day (each combined with at least 1 hour of near visual activity during patching)
- duration of occlusion is the important factor with most children requiring a total of 150-250 hours of patching to achieve the full effect (approximately 3 months of 3 hours per day)
- a child will require a higher total dose of occlusion the older they are at the start of treatment
- adherence
- both the child and parent/carer should be convinced of the need for treatment and appropriately motivated to carry it out
- giving older children a stake in their own treatment, for example with the use of patching diaries with stickers is helpful
- atropine
- is the pharmacological alternative to patching and has been shown to be as effective as patching in the treatment of moderate (20/40 to 20/100) amblyopia in children aged from 3 to 7 and to be well tolerated
- advantages - treatment is not cosmetically obtrusive, better compliance once the drops or ointment are instilled.
- disadvantages - less easy to monitor for occlusion amblyopia, presence of systemic side effects, such as flushing, hyperactivity and tachycardia, particularly in children with Down’s syndrome
- using atropine drops only once daily at weekends is as effective as atropine used every day in the treatment of moderate amblyopia.
If there is no improvement in acuity, reassess for previously undetected pathology.
- an increase or switch in treatment may be required if an underlying cause cannot be found
- recurrence of the condition is seen in 24% of children on cessation of treatment and may require maintenance patching or tapering of patching over a prolonged period
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