Alignment of optic nerve head optical coherence tomography B-scans in right and left eyes

Abstract

Symmetry analysis of right and left eyes can be a useful tool for early detection of eye diseases. In this study, we want to compare the Optical Coherent Tomography (OCT) images captured from optic nerve head (ONH) of right and left eyes. To do this, it is necessary to align the OCT data and compare equivalent B-scans in right and left eyes. For this reason, since the fovea-ONH axes in OCT data are not available due to small field of view in OCT, at first the projection of OCT data of each eye is registered to its corresponding fundus image using extracted vessels by Hessian analysis of directional curvelet subbands. Then, by alignment of fundus images of right and left eyes according to their automatically detected fovea-ONH axes, OCT projections are also aligned. After alignment of OCT projections, aligned B-scans are estimated and used for comparing different parameters such as cup-to-disk ratio (CDR). Using aligned B-scans, two signals of CDRs are obtained from two eyes which each point in these signals corresponds to CDR in a specific part of ONH, i.e., a point-to-point comparison between CDRs of right and left eyes is provided which has potential to lead to a new imaging biomarker for eye disease detection.