Evaluating Quantitative OCT Biomarkers Associated with Geographic Atrophy Growth Patterns in Dry Age-Related Macular Degeneration

Abstract

Purpose : With the recent advancements in the interventions for geographic atrophy (GA), the ability to predict growth rate for GA lesions is essential for precision decision-making for treatment initiation and risk-stratification. The goal of this analysis was to analyze advanced SD-OCT quantitative biomarkers in eyes with GA lesions and evaluate the impact on differential growth rates over a 2 year period.

Methods : This IRB-approved longitudinal retrospective analysis included eyes with advanced dry AMD that had SD-OCT assessments (Spectralis or Cirrus) at baseline and at year 2. GA (i.e.,cRORA) was defined as a minimum area of 0.5mm² (i.e., a minimum diameter of 250 μm) with RPE loss, outer retinal atrophy and hypertransmission. All scans were analysed, using a machine learning-enhanced multi-layer retinal segmentation [i.e.,ellipsoid zone(EZ), outer nuclear layer(ONL), retinal pigment epithelium(RPE)] platform and subsequent certified reader B-scan level correction of any segmentation errors. Square root transformation was performed for the GA area in evaluating growth rate over time. Fast and slow progressor groups were defined as upper quartiles (UQ) and lower quartiles (LQ) of growth rate, respectively.

Results : In this analysis of 541 eyes, the mean absolute growth rate of GA between the baseline and 2-year follow-up was 2.87±2.62 mm²/yr while the mean change in square root growth rate of GA was 0.43±0.32mm/yr. When comparing the baseline OCT biomarkers for the fast and slow progressors, Total EZ attenuation (EZ-RPE=0μm) and Partial EZ attenuation (EZ-RPE thickness≤20μm) was 12.19% (LQ), 13.76% (UQ) and 19.39% (LQ), 32.32% (UQ) respectively. In addition, Outer retinal volume (ONL-RPE) was 3.66mm³ (LQ) and 3.46mm³ (UQ) and Drusen volume (RPE-BM volume) was 0.55mm³ (LQ) and 0.60mm³ (UQ). All comparisions were statistically significant (p<0.05).

Conclusions : The present study identifies significant differences in various outer retinal parameters between slow and fast GA growth rate cohorts. Specifically, greater amounts of EZ loss, greater outer retinal thinning, and increased drusen volume are all associated with faster growth rate. These findings have important implications for ascertaining the growth rate and thus optimizing the designs of clinical trials and establishing relevant prognostic indicators in disease management.

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