Analysis of pulsatile motion in the murine cornea using phase-sensitive visible-light optical coherence tomography

The cornea is constantly exposed to cardio-pulmonary induced changes of intraocular pressure. Resulting pulsatile motion patterns in the eye may indicate severe pathological alterations of the biomechanical composition and the physiological function in affected tissue types. Non-contact measurements of pulsatile motion in the anterior eye could thus hold a diagnostic value, not only to assess biomechanics in corneal pathologies, but also pulsatile irregularities, resulting from the stimulus itself. Here, we present a methodology to measure physiologically induced tissue compression in the central murine cornea, based on a prototype for visible light optical coherence tomography (vis-OCT) providing 2-µm axial resolution and phase-related nanoscale measurements of displacement inside the corneal tissue. We present the in vivo assessment of pulsatile deformations in the cornea (passive stimulation) as well as ex vivo investigations of tissue oscillations induced by active stimulation using an air puff in the eyes of wild-type mice. The frequency spectra of corneal tissue oscillations were measured and showed good agreement with physiological control measures reported in the literature. Based on these preliminary results, revealing physiologically induced compression and air-puff induced nano-oscillations in the murine cornea, the methods may be extended towards optical coherence elastography in the visible range, to access biomechanical parameters, complementing the high-resolution structural imaging capabilities of vis-OCT.