Geographic atrophy area measurement: comparison between fundus autofluorescence and OCT

Abstract

Purpose : <div style="direction: ltr;">To compare geographic atrophy (GA) area and shape descriptors using fundus autofluorescence (FAF) annotation versus optical coherence tomography (OCT) annotation with complete retinal pigment epithelium and outer retinal atrophy (cRORA) criteria in cases of dry age-related macular degeneration (AMD).</div>

Methods : <div style="direction: ltr;">Retrospective annotation of GA in FAF and OCT in a single timepoint.</div> <div style="direction: ltr;">Primary outcomes: GA area, focality, perimeter, circularity and minimal distance from the center. The primary outcomes were compared between both modalities. Correlations of the primary outcomes on OCT with the difference in GA area between both modalities were analyzed using multivariate regression analysis. </div>

Results : <div style="direction: ltr;">30 pairs of FAF and OCT scans from 30 eyes of 18 patients with dry AMD were included. The mean total GA area measured 8.77±4.38 mm² with FAF and 2.78±3.39 mm² with OCT (P<0.0001). The mean FAF-OCT area difference was 5.99±4.22 mm². Multivariate regression analysis revealed a significant correlation between the FAF-OCT area difference and GA focality and minimal distance from the center on OCT (adjusted r² = 0.66).</div>

Conclusions : <div style="direction: ltr;">This study quantitatively measured and compared GA area using fundus autofluorescence as compared to OCT. The mean GA area measured on OCT was 3.15 times smaller than that on FAF. FAF-OCT area difference correlated with GA focality and minimal distance from the center on OCT. Further research is needed to establish the clinical application of these findings.</div>

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

<div style="direction: ltr;">GA annotation with OCT compared to FAF.</div> <div style="direction: ltr;">GA on corresponding (A) IR-OCT, (B) FAF, and (C) color pictures. GA annotation using cRORA criteria on an OCT B-scan is projected on the IR image (D; in red; 8.4 mm²). GA annotation on FAF (E; in blue; 12.5 mm²). The OCT (red) and FAF (blue outline) annotations are projected on the IR-OCT image (F). cRORA evident in the OCT B-scan (G; blue columns) corresponds only partly to the hypofluorescent areas seen in the level of that B-scan section on FAF.</div> <div style="direction: ltr;">IR-OCT= Infra-red Optical coherence tomography; FAF=fundus autofluorescence; GA=geographic atrophy; cRORA= complete retinal pigment epithelium and outer retinal atrophy</div>