Comparison of optical coherence tomography assessments in the comparison of age-related macular degeneration treatments trials.

OBJECTIVE To determine agreement between spectral-domain (SD) and time-domain (TD) optical coherence tomography (OCT) image assessments by certified readers in eyes treated for neovascular age-related macular degeneration (AMD). DESIGN Cross-sectional study within the Comparison of AMD Treatments Trials (CATT). PARTICIPANTS During year 2 of CATT, 1213 pairs of SD OCT and TD OCT scans were compared from a subset of 384 eyes. METHODS Masked readers independently graded OCT scans for presence of intraretinal fluid (IRF), subretinal fluid (SRF), and sub-retinal pigment epithelium (RPE) fluid and performed manual measurements of retinal, SRF, and subretinal tissue complex thicknesses at the foveal center. MAIN OUTCOME MEASURES Presence of fluid was evaluated with percent agreement, κ coefficients with 95% confidence intervals (CIs), and McNemar tests. Thickness measurements were evaluated with mean difference (Δ) ±95% limits of agreement and intraclass correlation coefficients (ICCs) with 95% CIs. RESULTS Between SD OCT and TD OCT, agreement on presence of any fluid was 82% (κ = 0.46; 95% CI, 0.40-0.52), with 5% more SD OCT scans demonstrating fluid (P<0.001). Agreement on presence of SRF was 87% and sub-RPE fluid was 80%, with more SD OCT scans demonstrating fluid (both P < 0.001). Agreement on IRF was 73% (κ = 0.47; 95% CI, 0.42-0.52), with 6% more TD OCT scans demonstrating fluid (P < 0.001). Between SD OCT and TD OCT, mean thickness of the retina was Δ = 5±67 μm, SRF was Δ = 1.5±35 μm, and subretinal tissue complex was Δ = 5±86 μm. Thickness measurements were reproducible for retina (ICC = 0.84; 95% CI, 0.83-0.86), SRF (ICC = 0.88; 95% CI, 0.86-0.89), and subretinal tissue complex (ICC = 0.91; 95% CI, 0.89-0.92), with ≤25-μm difference in these measurements in 71%, 94%, and 61% of paired scans, respectively. CONCLUSIONS Agreement on fluid presence and manual thickness measurements between paired scans from each OCT modality was moderate, providing a reasonable basis to compare CATT results with future SD OCT-based trials. Fluid was detected 5% more frequently with SD OCT, which may increase frequency of fluid-based treatment. Lower-resolution and artifactual interpretation of dark areas as cystoid edema may explain the greater frequency of IRF detected with TD OCT.