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E.L. Lambert, D. Wu, A. Goulding, L.–Y. Lee, M. Fisher, R.P. Danis; Macular Thickness Measurement Reproducibility Within Patient and Session by the OCT3 . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1546.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Replicate OCT images on normal and diseased eyes submitted to a central reading center for clinical trial certification were evaluated for reproducibility of macular thickness measurements given the conditions of the same patient, session, equipment and operator. Methods: Patient selection was determined at the clinical site for purposes of obtaining OCT operator certification. Certification applicants were asked to submit replicate fast macular thickness map scans of one "normal" eye (defined as an eye without obvious macular pathology) and one eye with the disease under study (either wet AMD or macular edema). All OCT3 sets submitted between Nov 2002 and Nov 2004 (n=281) were analyzed for differences between center point thickness measurements, center point standard deviations, and grid subfield measurements in the replicate scans. Center point thickness was used to create subgroups defined as < 175, 176–225, 226–325, 326–425, > 426 microns; these contained 87, 56, 45, 48, and 45 eyes respectively. Results: The mean absolute difference between replicate scan center point measurements increased with retinal thickness from 6 microns in the subgroup < 175 microns up to 23 microns in the > 426 microns subgroup (p<0.001). A similar relationship was observed for the center, inner, and outer subfields. For all 281 eyes, the overall mean absolute difference was 14 microns for the center point thickness (mean 284), 9 for the standard deviation of the center point (mean 14), 8 for the center subfield (mean 301), 20 for the inner subfields (mean 1253), and 19 for the outer subfields (mean 1032). Conclusions: Replicate OCT scans obtained in selected cooperative patients under optimal conditions demonstrate increasing variability with greater retinal thickness measurements, but quite modest mean absolute differences. These results suggest the standard deviation of the center point of the fast macular thickness map or another measure may be a useful quality metric.
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