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Treatment for mild amblyopia in one eye can safely be left beyond preschool years, according to a randomised controlled trial in the UK. The implications are far reaching as screening and treatment are practised world wide.
The single blind trial established that full treatment with glasses and eye patch benefited preschool children (age 3–5 years) with moderate (6/36–6/18) amblyopia, whose improved vision translated into one or two lines of the Snellen chart, but not those with mild (6/9–6/12) amblyopia over untreated children. Six months afterwards, when all children in need of glasses had them, the difference in visual acuity among the three groups was minimal, further suggesting that delay did no harm.
The trial assessed standard treatment for amblyopia—a patch and glasses—and glasses alone against no treatment in 177 children with amblyopia identified at standard preschool screening and referred to one of eight children’s eye clinics. Impairment ranged from 6/9–6/36. Children randomised to treatment had an initial assessment and reassessments at 24, 52, 54, and 78 weeks. Those receiving a patch and glasses had their patch fitted after six weeks’ wearing glasses, if indicated. Glasses were prescribed after 52 weeks for any child in any group who needed them and eye patches two weeks later.
Preschool screening is widespread owing to the belief that amblyopia is treatable only up to age 7 years, but its cost effectiveness and psychological impact have been queried. A systematic review has previously claimed that evidence in favour of treatment is lacking.