Abstract
Purpose :
Fundus Autofluorescence (FAF) is still the gold standard for lesion measurements ofin Geographic Atrophy (GA) in clinical trials, but clinical practice is moving towards using Optical Coherence Tomography (OCT). Therefore it is important to understand how the hypoFAF lesions on FAF correlate with the OCT findings. We correlated the hypoFAF lesion area with the area of RPE, photoreceptor and myoid Zone loss on OCT as well as with the amount of amorphous material - abnormal hyperreflective area (AM) in patients with AMD.
Methods :
We used a dataset obtained at the Medical Retina Department at the Jules-Gonin Eye Hospital with 180 OCT cube scans and corresponding FAF images (79 patients). Above mentioned retinal changes were computed on an individual B-scan level using the segmentation output of a trained convolutional neural network. HypoFAF lesions on FAF images were manually labeled and automatically aligned to infrared images to match GA areas for Dice score evaluations.
En-face areas of structural loss of MZ, EZ+OPR+IZ (PR) and RPE, as well as AM areas, were calculated.
OCT area measurements were correlated to FAF-measured GA areas. Relationships between measurements were obtained using Pearson correlation.
Results :
We observed strong positive correlations (Fig. 1) between FAF lesion area and areas of RPE loss, PR loss and MZ loss, respectively (0.96, 0.94, 0.93). Most lesion areas were clearly visible without significant cutouts within both modalities, which contributes to the observed correlations.
For RPE loss vs. FAF GA area R2 was 0.91. All correlation results showed P-values < 0.001.
We observed moderate positive correlations between FAF GA area and AM area (0.65).
Mean lesion area (FAF) was 4.70 mm2 (0.08-18.17 mm2 min-max), 4.45 mm2 for RPE loss area, 6.04 mm2 for EZ+OPR+IZ loss area, 5.86 mm2 for MZ loss area.
Quantitatively, the mean and standard deviation measured between FAF and OCT (RPE loss) GA areas resulted in 0.258 ±1.28 mm2. Mean Dice score was calculated between areas of RPE loss and registered FAF with values of 0.731 (0.193).
Conclusions :
The observed strong correlations between OCT and FAF measurements suggest that OCT can be used in GA assessment for clinical practice and clinical trials.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.