Spectral-domain Optical Coherence Tomography Retinal and Choroidal Thickness Metric Repeatability in Age-related Macular Degeneration

PURPOSE: To determine the intrasession repeatability of spectral-domain OCT (SDOCT)-derived macular retinal and choroidal metrics in patients with neovascular age-related macular degeneration (nAMD) in the Distance of Choroid Study (DOCS). DESIGN: Validity and reliability analysis. METHODS: Enrolled patients underwent repeated SDOCT imaging using the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). A single technician certified for clinical trials took 3 macular volume scans. Retinal thicknesses were calculated for each of the 9 Early Treatment Diabetic Retinopathy Study (ETDRS) macular subfields. Center point thickness and total macular volume were also included in the analysis. Manual subfoveal choroidal thickness measurements were made by a masked observer. RESULTS: A total of 40 eyes of 40 patients were included in this analysis (mean [+/- standard deviation] age: 74.1 [+/- 7.2] years, 60% male). The coefficient of repeatability (CR) of the central macular subfield was 30.6 mu m (95% confidence interval [CI] 29.8-1.4 mu m). The CR for the other macular subfields ranged from 7.0 mu m to 38.2 mu m. The CR for the total macular volume was 0.212 mm(3) (95% CI 0.206-0.217 mm(3)) and the CR for the center point was 47.5 mu m (95% CI 46.2-48.7 mu m). Images were also reviewed for the presence of segmentation error in the central macular subfield, and after exclusion of these eyes the revised CR for this subfield was 13.7 mu m (95% CI 13.3-14.1 mu m). The intrasession CR of subfoveal choroidal thickness was 34.7 mu m (95% CI 33.7-35.7 mu m). CONCLUSIONS: This study suggests that a change of greater than 31 mu m in Spectralis SDOCT-derived retinal thickness measurement of the central macular subfield and 35 mu m in subfoveal choroidal thickness is necessary to detect true clinical change associated with disease progression or improvement in nAMD with a revised figure of 14 mu m for central macular retinal subfield thickness in the absence of segmentation error. (C) 2016 Elsevier Inc. All rights reserved.