OCT-based dynamic mechanical analysis of vitreous humour

Abstract

The vitreous humour plays an important role in shock absorption, i.e. the damping of the mechanical movement, to protect the delicate tissues within the eye. However, this damping is different for movements with different frequencies/velocities. While the collective low-frequency (below 100 Hz) damping behaviour of the vitreous humour associated with the saccadic and lens movements is well-studied, to the best of our knowledge, the high-frequency damping behaviour of the vitreous humour, which represents the response of the microstructural components, is not exhaustively documented. Here, we utilise a non-destructive testing method called Optical Coherence Tomography (OCT) to measure the high-frequency (100–350 Hz, waves able to probe approximately 500 µm distances) biomechanical behaviour of the vitreous humour. We parametrise this behaviour by calculating the shear storage modulus, shear loss modulus and phase angle. We compare these parameters to their low-frequency counterparts obtained with a rheometer, providing a comprehensive mechanical spectrum of the vitreous humour behaviour. The processing method developed in this study and the data collected help better understand the vitreous humour shock absorption properties. Consequently, they could allow a development of better vitreous humour substitutes. The local probing of the high-frequency regime and the non-invasive character of the OCT method provide new qualities in mapping the damping behaviour.