Test-retest reproducibility of accommodation measurements gathered in an unselected sample of UK primary school children.

Abstract

To determine the test-retest reproducibility of accommodation measurements gathered in an unselected sample of primary school children. Monocular and binocular amplitudes of accommodation (AA) were collected by five different Testers using the push-up method in an unselected sample of school children (n=137, age: 8.1±2.1 years). Testing was conducted on three occasions (average testing interval: 8 days) in 91.2% of the children. The median AA was 19.1D, the variation due to the identity of the Tester was 3.1D (p<0.001) and the within-subject variation (which takes the variation due to Tester identity into account) was 5.2D. Around 75-79% of children exhibited monocular AAs≥12D when tested on the first occasion, but more than 90% exhibited an AA≥12D when subsequently tested. Around 74-80% of those with an AA<12D on the first occasion had values≥12D on subsequent testing even though no treatment had been undertaken. Poorer initial AA measurements were less likely to improve on repeat testing. Our results reveal substantial intra-individual variation in AA measurements, raising questions about the usefulness of this test in children aged 4-12 years. We suggest that AA assessment may prove most useful in children in this age range as a pass/fail check for substantially reduced AA, for example, where the AA is <12D. Our sample would suggest that the prevalence of persistently reduced AA may be around 3.2% when tested under binocular conditions and 4-6.4% when tested monocularly.