A systematic review 1 including 5 RCTs and 6 prospective controlled cohort studies without randomisation was abstracted in DARE. One prospective controlled trial and 16 retrospective studies of different screening programs were included. The target conditions were amblyopia, refractive errors and squints which are not cosmetically obvious. Treatment interventions included CAM vision stimulator, conventional orthoptic treatment, levodopa/karbidopa, prism adaptation, occlusion, surgery, and placebo.
No clear evidence for the effectiveness of treatments for any of the three target conditions was found. Most of the studies were methodologically flawed. No studies were found which compared treatment with no treatment.
Orthoptic screening programmes performed better than health visitor or GP screening in terms of yield and positive predictive value. Positive predictive value ranged from 47.5 to 95.9% for orthoptic screening and 14.4 to 61.5 for HV/GP screening. The one prospective study does not support the belief that identifying children with amblyopia in the preschool period reduces the prevalence of this condition in children aged seven.
The first randomized study 2showed that deferring treatment for 12 months in children with acuities of 6/36 or better does not have an adverse outcome, but we do not know whether this applies to children whose vision is worse than this at the outset. No project has dared to leave them untreated. We do not find the eyes with less than 6/36 visual acuity without examining all children and we would miss also children who have poor visual acuity in both eyes. Treatment could be restricted to the more severe cases. The study of Eibschitz-Tsimhoni et al 3 from Israel found that 8 year old children previously screened and treated for amblyopia had a 1% prevalence of amblyopia compared with 2.6% for a matched untreated population.
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