Three-dimensional shape analysis of peripapillary retinal pigment epithelium-basement membrane layer based on OCT radial images

Abstract The peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer angle was recently proposed as a potential index for estimating intracranial pressure noninvasively. However, the ppRPE/BM layer angle, measured from the optical coherence tomography (OCT) scans, varied across the radial directions of the optic disc. This made the ppRPE/BM layer angle difficult to be utilized in its full potential. In this study, we developed a mathematical model to quantify the ppRPE/BM layer angles across radial scans in relation to the ppRPE/BM 3D morphology in terms of its 3D angle and scanning tilt angles. Results showed that the variations of the ppRPE/BM layer angle across radial scans were well explained by its 3D angle and scanning tilt angles. The ppRPE/BM layer 3D angle was reversely fitted from the measured ppRPE/BM layer angles across radial directions with application to six eyes from four patients, who underwent medically necessary lumbar puncture. The fitted curve from our mathematical model matched well with the experimental measurements ( R ² > 0.9 in most cases). This further validated our mathematical model. The proposed model in this study has elucidated the variations of ppRPE/BM layer angle across 2D radial scans from the perspective of the ppRPE/BM layer 3D morphology. It is expected that the ppRPE/BM layer 3D angle developed in this study could be further exploited as a new biomarker for the optic disc.