Vision screening in children

In his article in the current issue of Deutsches Ärzteblatt International (Dtsch Arztebl Int 2010; 107[28-29]: 495-9), Wolf A. Lagrèze examines whether or not childhood screening for vision disorders in preschool children is worthwhile.

Eye disorders can occur even in very young children and may threaten their vision. Retinopathy of prematurity is currently the only eye disorder for which ophthalmological screening is provided in Germany. Childhood screening for other eye disorders would also be worthwhile if the disorder to be diagnosed were sufficiently common and successful treatment guaranteed.

Amblyopia is defined as a unilateral sight disorder that can weaken the affected eye or the visual apparatus as a whole. Strabismus, for example, hinders visual development and can be treated by temporarily covering the better eye. The most significant study conducted to date tested 6081 seven-year-olds and found that those who had been screened and treated as preschoolers developed visual problems somewhat less frequently than those who had not. The frequency of visual disorders also seems to be correlated to membership of certain social strata.

German law establishes vision screening as part of routine childhood examination. However, as not all the doctors who carry out such examination currently receive sufficient training, and as their remuneration is often too low to cover their costs, the program is probably unable to provide what the law establishes.

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SUMMARY

Background: Comprehensive, systematic reviews on the benefit of vision screening in preschool children were published in 2008 by major national organizations in both Germany and the United Kingdom. These reviews raised public interest in the topic.

Methods: This article contains a discussion of the sensitivity, specificity, efficacy, and cost-effectiveness of preschool vision screening, on the basis of the two national reports mentioned above as well as relevant literature retrieved by a selective PubMed search.

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).