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Kirill Larin, Michael D Twa, Fabrice Manns, Salavat Aglyamov; Noninvasive Quantitative Elastography of the Cornea and the Lens with Optical Coherence Elastography. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1959.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the capability of a novel combined focused ultrasound/air-puff and phase-sensitive optical coherence elastography (OCE) system to assess biomechanical properties of ocular tissues (such as cornea and the lens) in situ and in vivo in 3D.
Low-amplitude elastic deformations in mice and rabbit ocular tissues were measured by the OCE system consisting of a spectral-domain optical coherence tomography (OCT) combined with focused ultrasound (lens excitation) and air-puff (cornea excitation) systems used to produce a transient force on the tissue surface. The amplitude, temporal profile, and the speed of the deformations were used to reconstruct tissue biomechanical properties using novel analytical models. Gold standard uniaxial compressional tests were used to validate the OCE data.
The OCE measurements in rabbit lens showed that the amplitude and the relaxation rate of the displacements (and, thus, Young’s modulus and shear viscosity) of the young lenses were significantly larger than those of the mature lenses, indicating a gradual increase of the lens stiffness with age (2.5 kPa and 7.4 kPa, respectively), Fig. 1. 3D visualization of the elastic wave propagating in rabbit corneas shows the obvious velocity difference in normal (0.79±0.050 m/s) and CLX (2.00±0.23 m/s) corneas (Figure 2). Then, the frequency analysis allowed depth-resolved analysis of cornea biomechanical properties clearly demonstrating the biomechanical differences of the corneal layers. Finally, the stress-strain measurements using uniaxial mechanical tests confirmed the results obtained by the OCE system.
The results demonstrate that the OCE system can be used for noninvasive analysis and quantification of cornea and lens biomechanical properties in 2D (lens) and in 3D (cornea) and as a function of age or therapy (e.g. CLX procedures).
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