Model-based motion compensation for corneal topography by optical coherence tomography

Corneal topography is an essential tool in ophthalmology, in particular for surgical planning and diagnostics. Optical coherence tomography (OCT) enables cross-sectional or volumetric imaging with high resolution. It is, however, not widely used for corneal topography. A major reason for this is that conventional beam-scanning OCT is susceptible to eye motion compared to established modalities, which measure corneal shape in a single shot. To overcome this limitation, we propose a novel pipeline for motion-compensated OCT-based corneal topography. The pipeline includes three main features: (1) continuous, two-dimensional scanning; (2) the three-dimensional continuous motion compensation in postprocessing; and (3) regularised Zernike reconstruction. First, we evaluated our method on an eye phantom that is moved to mimic typical eye motion. The proposed motion compensation was able to determine and correct the movements of the phantom. Second, we performed an in vivo study on 48 eyes, measuring each eye twice with our OCT-based topography, Placido disc topography (Atlas 9000, Carl Zeiss Meditec), and Scheimpflug (Pentacam, Oculus) topography. We then compared the performance of the OCT-based topography to the reference topographies in terms of repeatability and equivalence. The results confirm the necessity and efficiency of the presented motion compensation and validate the proposed methods for scanning and reconstruction.