Comparison Of Blue-Light Autofluorescence and Ultrawidefield Green-Light Autofluorescence for Assessing Geographic Atrophy

Purpose The goal of this study was to evaluate and compare the inter-modality and inter-reader agreement of manual and semiautomated GA (Geographic Atrophy) area measurements in eyes with GA due to age-related macular degeneration (AMD) using conventional blue and ultrawidefield (UWF) green light fundus autofluorescence (FAF) systems. Methods FAF images of eyes with GA were obtained during a single visit using both the Spectralis HRA+OCT2 device and the Optos California device. Images were exported for masked analysis by two independent masked graders. The area of the GA lesion(s) was segmented and quantified (mm2) with a fully manual approach where the lesions were outlined using Optos Advance and Heidelberg Eye Explorer (HEYEX) software. In addition, for the Heidelberg blue FAF images, GA lesions were also measured using the instrument’s semi-automated software (Region Finder 2.6.4). For comparison between modalities/grading method, the mean values of the two graders were used. Intraclass correlation coefficients (ICC) were computed to judge the agreement between graders. Results 72 eyes of 50 patients were included in this study. There was nearly perfect agreement between graders for the measurement of GA area for all three modalities (Intraclass Correlation coefficient = 0.996 for manual Optos Advance, 0.996 for manual Heidelberg HEYEX, 0.995 for Heidelberg Region Finder). The measurement of GA area was strongly correlated between modalities, with Spearman correlation coefficients of 0.985 (p < 0.001) between manual Heidelberg and manual Optos, 0.991 (p < 0.001) for Region Finder versus manual Heidelberg, and 0.985 (p < 0.001) for Region Finder versus manual Optos. The absolute mean area differences between the Heidelberg manual vs Region Finder, manual Optos vs Region Finder, and manual Optos vs manual Heidelberg were 1.61 mm2 (p<0.001), 0.90 mm2 (p<0.001), and 0.71 mm2 (p<0.001), respectively. Conclusions We observed excellent inter-reader agreement for measurement of GA using either 30-degree blue FAF or UWF green FAF, establishing the reliability of UWF imaging for macular GA assessment. While the absolute measurements between devices were strongly correlated, they differed significantly, highlighting the importance of using the same device for a given patient for the duration of a study.