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Item type:Publication, Multiple optical elastography techniques reveal the regulation of corneal stiffness by collagen XII(Association for Research in Vision and Ophthalmology Inc., 2022-11-01)PURPOSE. Collagen XII plays a role in regulating the structure and mechanical properties of the cornea. In this work, several optical elastography techniques were used to investigate the effect of collagen XII deficiency on the stiffness of the murine cornea. METHODS. A three-prong optical elastography approach was used to investigate the mechanical properties of the cornea. Brillouin microscopy, air-coupled ultrasonic optical coherence elastography (OCE) and heartbeat OCE were used to assess the mechanical properties of wild type (WT) and collagen XII–deficient (Col12a1–/–) murine corneas. The Brillouin frequency shift, elastic wave speed, and compressive strain were all measured as a function of intraocular pressure (IOP). RESULTS. All three optical elastography modalities measured a significantly decreased stiffness in the Col12a1–/– compared to the WT (P < 0.01 for all three modalities). The optical coherence elastography techniques showed that mean stiffness increased as a function of IOP; however, Brillouin microscopy showed no discernable trend in Brillouin frequency shift as a function of IOP. CONCLUSIONS. Our approach suggests that the absence of collagen XII significantly softens the cornea. Although both optical coherence elastography techniques showed an expected increase in corneal stiffness as a function of IOP, Brillouin microscopy did not show such a relationship, suggesting that the Brillouin longitudinal modulus may not be affected by changes in IOP. Future work will focus on multimodal biomechanical models, evaluating the effects of other collagen types on corneal stiffness, and in vivo measurements. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Whole embryo biomechanics with reverberant optical coherence elastography(Optica Publishing Group (formerly OSA), 2024-05-20)Many morphogenesis processes during embryo development are fundamentally biomechanical processes, and disruption of these events can lead to debilitating congenital abnormalities. Imaging the biomechanical properties of embryos could provide insight into developmental disorders and could open new therapy avenues. However, current methods are invasive and are incapable of producing viscoelasticity maps of live samples in 3D. To overcome these limitations, we propose the use of reverberant shear wave fields in combination with optical coherence tomography (OCT) for high-resolution elastography at different developmental stages of murine embryos. A 1 kHz quasi-harmonic stimulation was applied to induce the diffuse shear field, which leveraged the heterogeneous microstructure and boundaries of the different tissue segments in the embryos. With this approach, we show how the shear wave speed (i.e., stiffness) of the spine, heart, and mid-brain increased as the embryo developed from embryonic day (E) 9.5 to E 11.5 at five separate stages. This noncontact technique is a promising method for imaging the biomechanical properties of different embryo structures during development with important applications for understanding developmental diseases and exploring treatments.