title: Measurement of quantitative viscoelasticity of bovine corneas based on lamb wave dispersion properties.
abstract: The viscoelastic properties of the human cornea can provide valuable information for clinical applications such as the early detection of corneal diseases, better management of corneal surgery and treatment and more accurate measurement of intra-ocular pressure. However, few techniques are capable of quantitatively and non-destructively assessing corneal biomechanics in vivo. The cornea can be regarded as a thin plate in which the vibration induced by an external vibrator propagates as a Lamb wave, the properties of which depend on the thickness and biomechanics of the tissue. In this study, pulses of ultrasound radiation force with a repetition frequency of 100 or 200 Hz were applied to the apex of corneas, and the linear-array transducer of a SonixRP system was used to track the tissue motion in the radial direction. Shear elasticity and viscosity were estimated from the phase velocities of the A0 Lamb waves. To assess the effectiveness of the method, some of the corneas were subjected to collagen cross-linking treatment, and the changes in mechanical properties were validated with a tensile test. The results indicated that the shear modulus was 137 ± 37 kPa and the shear viscosity was 3.01 ± 2.45 mPa · s for the group of untreated corneas and 1145 ± 267 kPa and was 0.16 ± 0.11 mPa · s for the treated group, respectively, implying a significant increase in elasticity and a significant decrease in viscosity after collagen cross-linking treatment. This result is in agreement with the results of the mechanical tensile test and with reports in the literature. This initial investigation illustrated the ability of this ultrasound-based method, which uses the velocity dispersion of low-frequency A0 Lamb waves, to quantitatively assess both the elasticity and viscosity of corneas. Future studies could discover ways to optimize this system and to determine the feasibility of using this method in clinical situations.
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Xinyu
authors: X
authors: Zhang
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Yin
authors: Y
authors: Yin
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Yanrong
authors: Y
authors: Guo
authors: Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, People's Republic of China.
authors: Ning
authors: N
authors: Fan
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Haoming
authors: H
authors: Lin
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Fulong
authors: F
authors: Liu
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Xianfen
authors: X
authors: Diao
authors: Department of Ultrasonography, Third People's Hospital of Shenzhen, Shenzhen, People's Republic of China.
authors: Changfeng
authors: C
authors: Dong
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China. Electronic address: chenxin@szu.edu.cn.
authors: Xin
authors: X
authors: Chen
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Tianfu
authors: T
authors: Wang
authors: National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
authors: Siping
authors: S
authors: Chen
mesh_terms: D000465:Algorithms; D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D003315:Cornea / Q000000981:diagnostic imaging* / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000379:methods*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D008954:Models, Biological; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D033081:Shear Strength / Q000502:physiology; D013314:Stress, Mechanical; D000069453:Ultrasonic Waves; D014783:Viscosity
keywords: Corneas; Cross-linking therapy; Elastography; Lamb waves; Radiation force; Ultrasound; Viscoelasticity