Photoreceptor-Retinal Pigment Epithelium Loss Ratio and Fundus Autofluorescence Patterns: Predicting Lesion Progression in Geographic Atrophy

Abstract

Purpose : The progression of geographic atrophy (GA) lesions in age-related macular degeneration varies significantly among individuals. The objective of this study was to assess the impact of the ratio between photoreceptor (PR) loss and retinal pigment epithelium (RPE) loss on the progression of GA. Additionally, the study aimed to explore the association between abnormal fundus autofluorescence (FAF) patterns and the PR/RPE loss ratio.

Methods : Multimodal images from 53 treatment-naïve patients with GA and a follow-up duration of 3-24 months were included in a retrospective analysis from a single-center, real-life database. The GA area was manually annotated on FAF images, following a standardized protocol. The areas of PR loss and RPE loss at baseline were manually annotated on optical coherence tomography (OCT) images and the ratio between these areas was calculated. FAF patterns at baseline were categorized into none, banded, patchy, focal, diffuse, and diffuse trickling by trained graders. The impact of these biomarkers on square root transformed GA (sqrt GA) size progression through month 24 was evaluated using a random slope and intercept model and Spearman correlation coefficients.

Results : The mean sqrt GA at baseline was 1.9 (1.34 SD) and the mean sqrt GA growth rate was 0.29 (0.03 SE) mm per year. Abnormal FAF outside of GA lesions was classified as none (19%), banded (8%), patchy (2%), focal (9%), diffuse (45%) and diffuse trickling (17%). Mean PR/RPE loss ratio at baseline was 1.95 +/- 1.55. Patients with diffuse and diffuse trickling FAF patterns showed higher PR/RPE loss ratios (Figure 1) as well as higher GA progression rates. Over time, GA progression rates were larger in patients with higher PR/RPE loss ratio at baseline (Spearman coefficient=0.38; Figure 2).

Conclusions : Eyes with higher PR/RPE loss ratios were more likely to exhibit diffuse and diffuse trickling FAF patterns and exhibited higher GA progression rates. Baseline characteristics derived from FAF and OCT images may offer additional information on lesion progression to assist individual treatment decisions or informing clinical trial designs.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Figure 1: FAF patterns vs. PR/RPE loss ratio as measured on OCT

 

Figure 2: Scatterplot between the slope of sqrt GA lesion progression and the ratio between PR/RPE loss ratio at baseline