Analysis of the current preschool vision screening in Denmark

To analyse the current vision screening programme for children attending school with respect to identifying children with significant refractive errors.

A total of 950 children from the municipality of Roskilde, Denmark, were invited to participate in a cross-sectional study of vision screening. 447 children aged 4.5-7 years participated in the study. The children completed a vision screening and a full eye examination. The vision screening consisted of visual acuity at distance (VA), visual acuity at distance with +2.0 glasses (VA+2), visual acuity at near (VAnear) and Lang II stereotest. A LogMAR-based picture chart was used for the vision testing. Significant refractive errors were defined as hyperopia ≥+3.5 D, myopia >1.0 D, astigmatism ≥1.25 D and anisometropia >1.0 D.

Using receiver operating characteristic (ROC) curves, we could compare the efficiency of VA, VA+2, VAnear, VA in combination with VA+2 and VA in combination with VAnear. Area under the curve (AUC) for VA, VA combined with VA+2 and VA combined with VAnear was 0.841, 0.857 and 0.857, respectively, that is all classified as 'very good' screening tools, whereas VA+2 and VAnear as single screening tools were classified as 'good' with AUC of 0.704 and 0.775, respectively. Using the optimal cut-off limit from the ROC curves, VA above 0.05 LogMAR as cut-off limit showed a sensitivity of 85.2% with a specificity of 74.9%. A slightly higher sensitivity could be found when combining screening tests, but with declining specificities.

Visual acuity at distance with the use of LogMAR-based charts is the optimal screening tool of choice; only minor improvements can be obtained combining with other tests.