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[Comparison of two visual acuity tests in school enrolment examinations : Tumbling E test versus Freiburg visual
M Bach1, M Reuter2, W A Lagrèze3
1Klink für Augenheilkunde, Universitätsklinikum Freiburg, Killianstr. 5, 79106, Freiburg, Deutschland. michael.bach@uniklinik-freiburg.de.
Background:
On the initiative of professionals performing vision screening for primary school enrolment, we compared the laptop-based Freiburg acuity and contrast test (FrACT) as a more easily portable alternative to the traditionally employed tumbling E vision test.
Methods:
We assessed vision with both methods in 326 children (647 eyes) aged 3.8-6.9 years. The FrACT was set to present the Landolt C optotype with the four cardinal orientations and automatic threshold bracketing over 18 presentations.
Results:
The 95% limits of agreement between both methods were ±0.125 logMAR and 95% of all test differences were within slightly more than ±1 line. Over the examined age range acuity significantly but weakly increased (p < 0.01) from 0.7 to 0.9 and for Landolt Cs the acuity gain was slightly higher by 0.02 logMAR per year. The FrACT results were ≥3 lines lower than those of the tumbling E chart in only 6 eyes. The examiners unanimously preferred FrACT.
Discussion:
The agreement between both tests of approximately ±1 lines is very high. The low outlier rate of <1% is deemed to be acceptable for a screening test.
