Optical Attenuation Coefficient-Based En Face Optical Coherence Tomography Imaging for the Reliable Assessment of the Ellipsoid Zone

Objective: This study used optical attenuation coefficient (OAC)-based optical coherence tomography (OCT) en face images to assess the ellipsoid zone (EZ) in the foveal region. Methods: This retrospective, observational, cross-sectional study of 41 healthy volunteers and 34 patients with retinal diseases included imaging data acquired using a prototype swept-source OCT system. EZ en face images were generated from OCT raster scan volumes based on OAC, followed by denoising and binarization to quantify the percentage of EZ structural normality or abnormality relative to the total imaging area. We evaluated the reliability of the OAC-based method compared with the OCT signal intensity-based method in healthy and diseased eyes. In addition, the validated program was applied to patients with various retinal conditions. Results: The estimated normal EZ area in healthy eyes was 96.2 ± 5.6% using the OAC-based method versus 89.3 ± 18.8% for the intensity-based method. The OAC-based method effectively mitigated various artifacts caused by retinal blood vessels and other factors in both healthy and diseased eyes. In a pilot study involving six diseased eyes, the area exhibiting EZ structural abnormalities was 27.5–99.6%. Conclusions: The OAC-based EZ assessment robustly suppressed image artifacts and reliably characterized structural abnormalities in the EZ from OCT volumes.