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Roberta Farci, Florence Coscas, Alexandre Sellam, Gabriel J Coscas, Maurizio Fossarello, Eric Souied, Giacomo Diaz; Comparison of reflectivity signal obtained by Enface OCT and OCT Angiography in cystoid macular edema.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1642.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: to evaluate images of macular cysts with different degrees of reflectivity (from gray to black signal) as observed in EnFace OCT with decorrelation signal obtained with OCT angiography (OCTA) in eyes with cystoid macular edema (CME) secondary to diabetic retinopathy (DR) and retinal vein occlusion (RVO).
Methods: images from 3033 patients affected by CME secondary to DR or RVO examined with SDOCT (Spectralis OCT, Heidelberg Engineering, Germany or Cirrus 5000 OCT, Zeiss, Germany), EnFace OCT and OCTA (Optovue XR Avanti, Optovue, USA) at the Eye Clinic Department of Créteil, France, and at the University Eye Clinic of Cagliari, Italy, were retrospectively examined. The deep capillary plexus OCTA images and the corresponding EnFace OCT images, both acquired with the same automatic segmentation, were overlapped to compose RGB color images as red and green channels, respectively, using ImageJ software (National Institutes of Health, Bethesda, MD). Then, linear regions of interest were traced on the color images to obtain the profiles of OCTA and EnFace gray values.
Results: we found 94 patients with DR and 27 patients with RVO showing intraretinal macular cystoid spaces with similar homogeneous, gray-looking content, and 73 patients with DR and 113 patients with RVO showing macular cystoid spaces with homogeneous, black-looking content, as observed at SDOCT, EnFace and OCTA scans. The analysis of red and green profiles demonstrated a clearly visible overlapping between the average OCTA and EnFace signal observed around cystoid spaces, that could be attributed to a relationship between the dynamic vascularization and structural density of the tissue. In fact, OCTA profiles show sharp peaks, whereas EnFace profiles show somewhat parallel, but smoother changes. A similar overlapping of red and green plots was also found inside the cystoid spaces.
Conclusions: we found a constant overlapping between the vascular signal (OCTA) and the structural signal (EnFace OCT) both outside and inside the cystoid spaces examined. Since OCTA is a technique that employs motion contrast to detect erythrocyte movements in retinal blood vessels, the low intensity OCTA signals observed inside cystoid spaces, pose a relevant question about their nature, as to whether they are due to the presence of corpusculated content or must be considered OCTA artifacts.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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