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D. J. Browning, Diabetic Retinopathy Clinical Research Network; Optical Coherence Tomography Measurements and Analysis Methods in Optical Coherence Tomography Studies of Diabetic Macular Edema. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1859. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate Stratus (Carl Zeiss Meditec; Dublin, CA) optical coherence tomography (OCT) measurements and methods of analysis of OCT data in studies of diabetic macular edema (DME).
We examined associations of pairs of OCT variables and results of three analysis methods using data from two studies of DME. Participants included 263 subjects from a randomized trial comparing two photocoagulation techniques for DME and 96 subjects from a diurnal variation of DME study. Correlations were calculated for OCT variables at baseline and for changes in the variables over time. Distribution of OCT measurement changes, predictive factors for OCT measurement changes, and treatment group outcomes were compared when three measures of change in macular thickness were analyzed: absolute change in thickness, relative change in thickness, and relative change in thickening where thickening was defined as the observed thickness minus the mean normal thickness. Concordance of results using different OCT variables and analysis methods was evaluated.
Mean center point thickness correlated highly with mean central subfield thickness (CSMT) at baseline (0.98-0.99). Changes in CSMT were approximately normally distributed for absolute and relative change in thickness, but not for relative change in thickening. From the randomized trial, macular thinning in the standard laser group was significantly greater when absolute change in thickness was used, but not when relative change in thickness and thickening were used. Relative change in macular thickening provides unstable data in eyes with mild degrees of baseline thickening, unlike the situation with absolute or relative change in retinal thickness.
CSMT is the preferred Stratus OCT measurement for the central macula because of its higher reproducibility and correlation with other measurements of the central macula. Total macular volume may be preferred when the central macula is less important. Absolute change in retinal thickness is the preferred analysis method in studies involving eyes with mild macular thickening. Relative change in thickening may be preferable when retinal thickening is more severe.
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