Vision screening programmes for amblyopia (lazy eye)

Amblyopia, commonly known as “lazy eye”, is the term used to describe a type of reduced vision that develops in childhood. Amblyopia is relatively common, affecting approximately 2% of children. If treated while the visual system is still maturing amblyopia can usually be reversed and normal vision restored. In most cases amblyopia only affects one eye so even quite severe amblyopia may go unnoticed by parents or caregivers. Screening programmes have, therefore, been set up to test children’s vision, in each eye separately, in order to detect the condition while the child is young and treatment is still possible. This review was designed to examine the evidence to see if such screening programmes are effective in reducing the prevalence of untreated amblyopia. The review found that there is currently not enough evidence to determine whether or not screening programmes reduce the proportion of older children and adults with amblyopia. The authors concluded that there is, therefore, a need for some robust evaluation of the screening programmes that are in place to see if they are truly effective or not. Any such evaluation would have to also look at how much screening programmes cost and what effect untreated amblyopia has on quality of life.

Authors' conclusions: 

The lack of data from randomised controlled trials makes it difficult to analyse the impact of existing screening programmes on the prevalence of amblyopia. The absence of such evidence cannot be taken to mean that vision screening is not beneficial; simply that this intervention has not yet been tested in robust trials. To facilitate such trials normative data on age-appropriate vision tests need to be available and a consensus reached regarding the definition of amblyopia. In addition, the consequences of living with untreated amblyopia have yet to be quantified and a cost-benefit analysis carried out.

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Background: 

Amblyopia is a reversible deficit of vision that has to be treated within the sensitive period for visual development. Screening programmes have been set up to detect this largely asymptomatic condition and refer children for treatment while an improvement in vision is still possible. The value of such programmes and the optimum protocol for administering them remain controversial.

Objectives: 

The objective of this review was to evaluate the effectiveness of vision screening in reducing the prevalence of amblyopia.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2008), MEDLINE (January 1950 to August 2008) and EMBASE (January 1947 to August 2008). The electronic databases were last searched on 15 August 2008. No language restrictions were placed on these searches. No handsearching was done.

Selection criteria: 

We planned to analyse data from randomised controlled trials and cluster-randomised trials comparing the prevalence of amblyopia in screened versus unscreened populations.

Data collection and analysis: 

Two authors independently assessed study abstracts identified by the electronic searches. Full text copies of appropriate studies were obtained and, where necessary, authors were contacted. No data were available for analysis and no meta-analysis was performed.

Main results: 

Despite the large amount of literature available regarding vision screening no trials designed to compare the prevalence of amblyopia in screened versus unscreened populations were found.

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