Abstract
Purpose :
Optical Coherence Tomography Angiography (OCTA) provides a non-invasive and high-resolution method to assess retinal structure using three-dimensional and depth-resolved scans of its layers. In patients diagnosed with age-related macular degeneration (AMD), it allows for the analysis and quantification of pathologic changes in the choriocapillaris circulation. The goal of this study was to develop a framework for analyzing choriocapillaris flow voids in patients with geographic atrophy (GA) based on OCTA.
Methods :
The dataset used are images from the OMEGA study which contains 23 eyes from 19 patients that were diagnosed with GA secondary to AMD. The patients’ scans were obtained at baseline from this longitudinal study that is aimed to characterize the natural history of the disease. As preprocessing, areas affected by drusen and geographic atrophy (GA) were masked manually via a drawing tool in MATLAB, to label regions on the custom extracted structure slabs where the contrast of GA/drusen to background is the highest. Finally, the images are compensated for shadowing using the structural OCT images. The remaining region of interest is binarized where intensities less than 1standard deviation below the mean of the image is marked as flow voids, and used to calculate the flow void percentage, number and average size. These values are calculated multiple times, using minimum size thresholds of 0 µm, 200µm, 400 µm, 600 µm and 800 µm.
Results :
The values obtained with a 400 µm threshold are flow void percentage, number of flow voids, and average flow void size are 11.8%±0.85%, 2194.2±384.4 1563.8 µm2 ±241.8 µm2, respectively. Correlation methods were used to study the association between GA area, drusen area and the flow void parameters. Only one significant correlation was obtained for GA area and flow void number, with correlation coefficient r = -0.69 (p<0.01).
Conclusions :
We provide a standardized framework of analyzing choriocapillaris flow voids in patients with GA. This technique to quantify choriocapillaris flow deficits bears the potential to be used in future clinical trials as outcome parameter.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.