Assessing the mechanical properties of tissue-mimicking phantoms at different depths as an approach to measure biomechanical gradient of crystalline lens

Abstract

Abstract:We demonstrate the feasibility of using the dominant frequency of the sample surface response to a mechanical stimulation as an effective indicator for sensing the depthwise distribution of elastic properties in transparent layered phantom samples simulating the cortex and nucleus of the crystalline lens. Focused ultrasound waves are used to noninvasively interrogate the sample surface. A phase-sensitive optical coherence tomography system is utilized to capture the surface dynamics over time with nanometer scale sensitivity. Spectral analysis is performed on the sample surface response to ultrasound stimulation and the dominant frequency is calculated under particular loading parameters. Pilot experiments were conducted on homogeneous and layered tissuemimicking phantoms. Results indicate that the mechanical layers located at different depths introduce different frequencies to the sample surface response, which are correlated with the depth-dependent elasticity of the sample. The duration and the frequency of the ultrasound excitation are also investigated for their influences on this spectrum-based detection. This noninvasive method may be potentially applied for localized and rapid assessment of the depth dependence of the mechanical properties of the crystalline lens.

Noncontact depth-resolved micro-scale optical coherence elastography of the cornea

“…This provides the OCT system with the sensitivity of ~7 nm to the corneal displacement, which greatly reduces the required amplitude of the corneal deformation for efficient imaging and measurements. More details of this OCT system can be found in our previous work [51,52]. Fig.…”

Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

“…The 135 system's phase stability measured by recording the interference from the reflection of the two surfaces of a glass slide placed in 136 the sample arm was ~4 milliradians. More details of this OCT system setup can be found in our previous publications 34, 37,38 . 137…”

Noncontact depth-resolved micro-scale corneal elastography

“…Such air stream results in small deformation of the cornea with the typical amplitude below 1-2 μm, which could help to preserve the structural and functional properties of the cornea during measurement. To capture the induced corneal temporal displacement, phase-resolved OCT detection based on a spectral domain OCT system [33,34] is employed with the motion sensitivity of ~ 7 nm from the tissue of cornea. The approach of imaging Lamb wave propagation in the cornea can be found in our previous work [26].…”