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

      Adler, P.; Scally, Andy J.; Barrett, Brendan T. (2012)
      Purpose To determine the test-retest reproducibility of accommodation measurements gathered in an unselected sample of primary school children. Methods 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. Results 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. Conclusions 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.
    • Test-retest reproducibility of accommodative facility measures in primary school children

      Adler, P.; Scally, Andy J.; Barrett, Brendan T. (2018-11)
      Background: To determine the test-retest reproducibility of accommodative facility (AF) measures in an unselected sample of UK primary school children. Methods: Using 2.00 DS flippers and a viewing distance of 40 cm, AF was measured in 136 children (range 4–12 years, average 8.1 2.1) by five testers on three occasions (average interval between successive tests: eight days, range 1–21 days). On each occasion, AF was measured monocularly and binocularly, for two minutes. Full datasets were obtained in 111 children (81.6 per cent). Results: Intra-individual variation in AF was large (standard deviation [SD] = 3.8 cycles per minute [cpm]) and there was variation due to the identity of the tester (SD = 1.6 cpm). On average, AF was greater: (i) in monocular compared to binocular testing (by 1.4 cpm, p < 0.001); (ii) in the second minute of testing compared to the first (by 1.3 cpm, p < 0.001);(iii) in older compared to younger children (for example, AF for 4/5-year-olds was 3.3 cpm lower than in children ≥10 years old, p = 0.009); and (iv) on subsequent testing occasions (for example, visit-2 AF was 2.0 cpm higher than visit-1 AF, p < 0.001). After the first minute of testing at visit-1, only 36.9 per cent of children exceeded published normative values for AF (≥11 cpm monocularly and≥8 cpm binocularly), but this rose to 83.8 per cent after the third test. Using less stringent pass criteria (≥6 cpm monocularly and≥3 cpm binocularly), the equivalent figures were 82.9 and 96.4 per cent, respectively. Reduced AF did not co-exist with abnormal near point of accommodation or reduced visual acuity. Conclusions: The results reveal considerable intra-individual variability in raw AF measures in children. When the results are considered as pass/fail, children who initially exhibit normal AF continued to do so on repeat testing. Conversely, the vast majority of children with initially reduced AF exhibit normal performance on repeat testing. Using established pass/fail criteria, the prevalence of persistently reduced AF in this sample is 3.6 per cent.
    • Test-retest variability of Randot stereoacuity measures gathered in an unselected sample of UK primary school children

      Adler, P.; Scally, Andy J.; Barrett, Brendan T. (2012)
      AIM: To determine the test-retest reliability of the Randot stereoacuity test when used as part of vision screening in schools. METHODS: Randot stereoacuity (graded-circles) and logMAR visual acuity measures were gathered in an unselected sample of 139 children (aged 4-12, mean 8.1+/-2.1 years) in two schools. Randot testing was repeated on two occasions (average interval between successive tests 8 days, range: 1-21 days). Three Randot scores were obtained in 97.8% of children. RESULTS: Randot stereoacuity improved by an average of one plate (ie, one test level) on repeat testing but was little changed when tested on the third occasion. Within-subject variability was up to three test levels on repeat testing. When stereoacuity was categorised as 'fine', 'intermediate' or 'coarse', the greatest variability was found among younger children who exhibited 'intermediate' or 'coarse'/nil stereopsis on initial testing. Whereas 90.8% of children with 'fine' stereopsis (</=50 arc-seconds) on the first test exhibited 'fine' stereopsis on both subsequent tests, only approximately 16% of children with 'intermediate' (>50 but </=140 arc-seconds) or 'coarse'/nil (>/=200 arc-seconds) stereoacuity on initial testing exhibited stable test results on repeat testing. CONCLUSIONS: Children exhibiting abnormal stereoacuity on initial testing are very likely to exhibit a normal result when retested. The value of a single, abnormal Randot graded-circles stereoacuity measure from school screening is therefore questionable.