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The biomechanical measurement of the crystalline lens can provide valuable information to assess the development of lens-related diseases, such as presbyopia and cataracts. Optical coherence elastography (OCE) has been used to measure the elasticity of the lens surface based on elastic wave imaging. However, measuring the elasticity of the lens interior poses a challenge because optical imaging cannot easily visualize elastic waves in the transparent lens. In this study, we develop an acoustic radiation force optical coherence elastography (ARF-OCE) method to detect the propagation of elastic waves on the surface of the lens and inside the lens for the elasticity measurement. The ultrasonic radiation force excites the lens from the side of the eye, subsequently inducing an elastic wave on the lens surface or inside the lens. Optical coherence tomography (OCT) images the crystalline lens from the front of the eye with the optical beam perpendicular to the acoustic beam. When the ARF is focused on the surface of the lens, the wave propagation on the lens surface is visualized by the OCT, and the elasticity of the lens surface can be quantified. When the ARF is focused inside the lens at different depths, the time the elastic wave reaches the lens surface will change. Therefore, the velocity of the elastic wave propagation inside the lens is calculated by the ratio of the depth change to the time difference, and the elasticity of the lens interior can be quantified. The elasticity of the surface and the interior of the ex-vivo porcine lens was measured using the ARF-OCE method. The elasticity measurement of the crystalline lens provides a quantitative assessment of its biomechanical properties and has the potential for the accurate diagnosis and treatment of lens-related diseases.
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