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G. P. Sharpe, P. H. Artes; Comparison of the Moorfields Motion Displacement Test to Standard Automated Perimetry. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5500.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the threshold tests of the Moorfields Motion Displacement Test (MDT) to those of standard automated perimetry (SAP) in patients with glaucoma.
A group of 22 glaucoma patients (mean MD, -3.4 dB; range, +1.2 to -10.6 dB) attended six sessions within a 12 week period. During each session, one eye was examined with the MDT (WEBS Threshold Test) and with SAP (Swedish Interactive Threshold Algorithm [SITA] Standard 24-2 test), in random order.Test-retest variability was derived from the SD of the 6 repeated threshold estimates, and retest intervals were derived by comparing each unique combination of 2 baseline tests with a single follow-up examination. Signal-to-Noise Ratios (SNRs) were derived from the superior-inferior differences between the 5 mirror-pair sectors of the Glaucoma Hemifield test.
Thresholds of MDT (min arc) and SAP (dB) were moderately related (Spearman r = -0.65; P < 0.001). Both techniques showed an increase in test-retest variability with decreasing sensitivity (Spearman r = 0.63 and -0.54 with MDT and SAP, respectively, p<0.001). When MDT thresholds were scaled logarithmically, however, the retest variability was nearly uniform throughout the dynamic range of the test (Spearman r = 0.18). The retest intervals suggested that the effective dynamic range of the tests is limited by a floor effect at approximately 18 min arc with the MDT and 21 dB with SAP. In comparison with SAP, the MDT showed a larger proportion of test locations at which the most intense stimulus was not seen (10.2% vs. 3.6% with MDT and SAP, respectively, p<0.001). The SNRs of SAP were larger than those of the MDT by a factor of 2.0.
The lower signal-to-noise ratios suggest that the current threshold MDT test offers few advantages over threshold SAP in measuring localised visual field loss and its progression. This, however, is probably related to the smaller number of test locations (32 compared to 54). Logarithmic spacing of the stimulus scale may help to improve the variability characteristics of the MDT.
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