Vision Screening in Preschool Children

Results: All studies that have been published to date on the efficacy of preschool visual screening suffer from methodological flaws. The avail able data suggest a benefit from screening, though this has not been proven. Model calculations reveal that the positive predictive value of screening tests performed in isolation is inadequate. The authors of the two national reports applied different methods and arrived at similar, but not identical conclusions. Preschool vision screening may also be cost-effective; whether this is the case or not depends on the probability of a long-term benefit—specifically, on the probability of preventing bilateral loss of vision in adulthood. To prevent one such case, it is estimated that 13 cases of childhood amblyopia must be identified and successfully treated (number needed to treat [NNT] = 13).