3D heartbeat optical coherence elastography to map the elasticity of the cornea

Abstract

Assessing corneal biomechanical properties may be important for the diagnosis of ocular diseases as the mechanical properties of the cornea change during disease development. Elastography is a technique to image the mechanical properties of tissues by applying a mechanical load to the tissue and measuring the resultant displacement using available imaging techniques like magnetic resonance or ultrasound imaging. The measured displacement is then translated to mechanical properties. Heartbeat optical coherence elastography (Hb-OCE) is a completely passive elastography technique, which uses physiological perturbations naturally present in the body in lieu of active tissue stimulation sources. In this work, we demonstrate the first use of 3D Hb-OCE to measure the biomechanical properties of the cornea in 3D in an ex vivo porcine eye. Measurements were taken on whole porcine eye globes using a Fourier Domain Mode Locked swept source laser-based OCT system with a volume rate of 4.2 Hz. The strain in the cornea was measured between successive B-scans during a simulated ocular pulse, and each scan was stacked together to obtain 3D volumetric strain due to the simulated heartbeat. This technique may potentially enable full volumetric analysis of corneal mechanical properties completely passively. Future work will focus on 3D evaluation of customized corneal crosslinking and in vivo translation of the 3D Hb-OCE technique.