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Michael D Twa, Gongpu Lan, Salavat Aglyamov, Kirill Larin; Clinical Application of Optical Coherence Elastography for Corneal Biomechanics. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6828. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Determining the biomechanical properties of corneal and other soft tissues is a longstanding challenge and active area of research. We have previously reported non-invasive elasticity imaging techniques to estimate Young’s modulus for ocular tissues in vitro and in animal models. Here we report the application of these methods for clinical measurements of corneal biomechanical properties.
Phase-sensitive optical coherence tomography imaging was combined with micro-air pulse tissue stimulation to perform dynamic elasticity measurements in 5 eyes of 5 participants. Low-force (13 Pa) spatiotemporally discreet (150µm; 800µs) tissue stimulation produced submicron-scale tissue deformations measured over a 2.5mm2 area. Surface wave velocity was measured and used to determine tissue stiffness. These measures were compared with corneal thickness, IOP and metrics from the Ocular Response Analyzer (CRF and CH).
Dynamic sub-micron corneal surface wave deformation responses were measured with excellent repeatability over a wide amplitude range (see Figure). Measured surface wave velocity ranged from 2.2 to 6.6 m/s between participants and correlated highly with IOP (r2=.58) and CRF (r2=.39), but not central corneal thickness (r2=.018).
Measurements of sub-micron corneal surface wave velocity enable clinical determinations of tissue stiffness in vivo with high precision. These observations will be combined with our previous results from elastography studies of corneal thickness, hydration, curvature, anisotropy, and IOP to provide a more comprehensive model of corneal biomechanics. We will use these measures in future studies to characterize the biomechanical responses of ocular tissues to disease and monitor the effects of clinical interventions, e.g. corneal cross-linking.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Illustration of sub-micron corneal displacement amplitude (0.1 to 0.6 µm) as a function of distance (right panel). Elastic wave propagation speed (3 m/s) is computed from the observed distance/time relationship (left panel).
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