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M. Wall, C. F. Brito, K. R. Woodward, C. K. Doyle, P. Artes; Repeatability of Automated Perimetry: A Comparison of Perimetric Tests Using Stimulus Size III, Size V, Matrix and Motion. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1619. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Standard perimetry is limited by a marked increase in variability with decreasing sensitivity. To evaluate this issue, we investigated the retest variability of four perimetry tests: Standard Automated Perimetry size III (SAP III), SAP size V (SAP V), Matrix (FDT II) and Motion Perimetry.
We tested one eye of 120 glaucoma patients with these four perimetric tests on the same day and retested 1-8 weeks later. The tests’ scales were adjusted to make their dynamic ranges similar. Point-wise limits of test-retest variability were then established from the empirical 5th and 95th percentiles of the distribution of retest values, stratified by the value of at the first test (Fig). The log differences between test and retest values were linearly regressed onto the averages of the two tests to determine the relationship between variability and sensitivity.
With SAP III, variability as shown by the test-retest intervals increased greatly with reduced sensitivity (Fig). Corresponding increases with SAP V, Matrix, and Motion perimetry were considerably smaller (p<0.001). With SAP III, sensitivity explained 22% of the test-retest variability (r2), while corresponding figures for SAP V, Matrix and Motion perimetry were 12%, 2%, and 2%, respectively.
Variability of Matrix and Motion perimetry does not increase substantially as sensitivity decreases. Increased sampling with the larger stimuli of these techniques is the likely basis for this finding. These properties may make these stimuli excellent candidates for early detection of visual field progression.
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