Diagnostic accuracy of vision screening tests for the detection of amblyopia and its risk factors: a systematic review.

Aim: This systematic review evaluates the diagnostic accuracy of preschool vision screening tests for the detection of amblyopia and its risk factors.

Methods: The literature searches were conducted in nine bibliographic databases. No limitation to a specific study design, year of publication or language was applied. Studies were included if they compared a vision screening test with a reference test (gold standard) in children from the general population. In addition, the studies had to provide sufficient data to calculate diagnostic accuracy (sensitivity and specificity). Full-text articles were assessed for studies that satisfied the inclusion criteria using the "Quality of Diagnostic Accuracy Studies (QUADAS)" checklist.

Results: Two studies with a longitudinal design and 25 cross-sectional studies met the inclusion criteria. One of the longitudinal studies compared a screening programme in children between 1 and 2 years of age with a re-examination at the age of 8. The sensitivity for the screening programme was 86% (range: 64-97%) and the specificity 99% (range: 98-99%). The second longitudinal study compared screening examinations at 8, 12, 18, 25 and 31 months, with a re-examination at the age of 37 months. In this study, the sensitivity of the screening examination increased with age, while the specificity remained unchanged. The cross-sectional studies evaluated different screening settings, visual acuity tests, auto- or photorefractors and stereo tests. A large variety of reference tests, differing criteria for defining amblyopia and its risk factors and methodological limitations of the studies prevented a valid data interpretation.

Conclusion: Diagnostic test accuracy of preschool vision screening tests can only be sufficiently investigated after establishing age-related values defining amblyopia, refractive errors and binocular disorders. To address these questions, we recommend a controlled longitudinal study design.