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Kirill Larin, Salavat Aglyamov; Acoustic radiation force-based elastography of the crystalline lens. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3169.
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© ARVO (1962-2015); The Authors (2016-present)
The development of several degenerative diseases in human eye, such as presbyopia and cataract, is associated with a stiffening of the crystalline lens. For a more complete understanding of the role of the lens biomechanics in the eye disorders, there is a need of noninvasive technique for in vivo measurement of the mechanical properties of the lens. However, the location of the lens inside the eye globe makes it challenging to measure its mechanical properties in vivo or in situ. To create a noninvasive method assessing the mechanical properties of the lens in situ and, potentially, in vivo, we propose to combine acoustic radiation force (ARF) with OCT and ultrasound imaging techniques.
To test proposed approach fresh rabbit and porcine eyeballs were used. ARF was generated on the surface of the lenses using single element or array ultrasound transducers with central frequency range from 3.5 to 4.4 MHz. To measure displacements on the lens surface ultrasound imaging system (V1, Verasonics Inc., Kirkland, WA, USA) and phase sensitive OCT systems were used. The OCT system was based on a superluminescent light diode with a central wavelength of 840 nm, and bandwidth of 49 nm. The acquisition speed of line scan camera was set to 25 kHz. A homemade closed-loop IOP control system was used to set the pressure inside the eye-globes. To quantitatively characterize biomechanical properties of the lens different parameters, like surface wave speed, relaxation rate, maximum displacement and model-based reconstructed Young’s modulus were used.
Results of the measurements in situ showed an approximately 3-fold increase of stiffness in the mature rabbit lenses in comparison with the young lenses. We demonstrated also that the stiffness of the lens increases as the IOP increases. However, results of both OCT and ultrasound-based measurements showed that the changes in lenticular stiffness is much less pronounced than changes in the stiffness of other ocular tissues, as cornea and sclera, due to elevated IOPs. Additionally, we demonstrated that cataract formation significantly affects lens mechanical properties as well.
The use of ARF in combination with OCT and ultrasound imaging, was demonstrated as a promising tool for noninvasive assessment of the biomechanical properties of the crystalline lens as a function of age, IOP, and cataract formation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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