Comparison of Multimodal Imaging for the Characterization of Geographic Atrophy

The purpose of this study was to compare the performances of infrared (IR), fundus autofluorescence (FAF), and multicolor (MC) imaging in the characterization of geographic atrophy, with a focus on the possibility to detect incomplete retinal pigmented and outer retinal atrophy (iRORA) on en face imaging.

The ground truth was established by two graders evaluating atrophy on spectral-domain optical coherence tomography (SD-OCT) images. A score for visibility of foveal sparing and margins of atrophy was attributed. Measurement of the atrophic area and the fovea-to-margin distance were performed. Accuracy of detection of foveal sparing was evaluated through comparison with B-scan images ground truth, with/without the inclusion of patients with foveal iRORA.

Seventy patients were included in this study. Foveal sparing and atrophy's margins subjective visibility were significantly higher rated on MC images compared to IR and FAF (P < 0.005 and P < 0.001). Agreement with OCT B-scan assessed foveal sparing revealed a significantly higher area under receiver operating characteristic curves (AUROC) for MC images at the analysis performed both with (0.876) and without (0.853) inclusion of patients with foveal iRORA (P < 0.001 and P = 0.006). Quantitative measurements revealed lower atrophy extension (P = 0.026) and fovea-to-margin distance (P = 0.019) with MC imaging.

MC imaging performed better at foveal sparing assessment, especially in the setting of foveal iRORA. MC also resulted in higher visibility of atrophy's margins, lower atrophy extension measurements, and lower distance from the fovea to atrophy's margins compared to both FAF and IR.

MC rated significantly higher in foveal sparing and atrophy detection, higher visibility of atrophy's margins, lower atrophy extension measurements, and lower distance from the fovea to atrophy's margins, compared to FAF and IR.