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Sensors 2018, 18(12), 4244; https://doi.org/10.3390/s18124244

High-Resolution Shear Wave Imaging of the Human Cornea Using a Dual-Element Transducer

1
Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan
2
Department of Microbiology and Immunology, National Cheng Kung University, Tainan 701, Taiwan
3
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
4
Department of Ophthalmology, Roski Eye Institute, University of Southern California, Los Angeles, CA 90089, USA
5
Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan
*
Author to whom correspondence should be addressed.
Received: 11 October 2018 / Revised: 22 November 2018 / Accepted: 30 November 2018 / Published: 3 December 2018
(This article belongs to the Special Issue Ultrasound Transducers)
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Abstract

Estimating the corneal elasticity can provide valuable information for corneal pathologies and treatments. Ophthalmologic pathologies will invariably cause changes to the elasticity of the cornea. For example, keratoconus and the phototoxic effects of ultraviolet radiation usually increase the corneal elasticity. This makes a quantitative estimation of the elasticity of the human cornea important for ophthalmic diagnoses. The present study investigated the use of a proposed high-resolution shear wave imaging (HR-SWI) method based on a dual-element transducer (comprising an 8-MHz element for pushing and a 32-MHz element for imaging) for measuring the group shear wave velocity (GSWV) of the human cornea. An empirical Young’s modulus formula was used to accurately convert the GSWV to Young’s modulus. Four quantitative parameters, bias, resolution, contrast, and contrast-to-noise ratio (CNR), were measured in gelatin phantoms with two different concentrations (3% and 7%) to evaluate the performance of HR-SWI. The biases of gelatin phantoms (3% and 7%) were 5.88% and 0.78%, respectively. The contrast and CNR were 0.76, 1.31 and 3.22, 2.43 for the two-side and two-layer phantoms, respectively. The measured image resolutions of HR-SWI in the lateral and axial directions were 72 and 140 μm, respectively. The calculated phase SWV (PSWV) and their corresponding Young’s modulus from six human donors were 2.45 ± 0.48 m/s (1600 Hz) and 11.52 ± 7.81 kPa, respectively. All the experimental results validated the concept of HR-SWI and its ability for measuring the human corneal elasticity. View Full-Text
Keywords: human corneal elasticity; high-resolution shear wave imaging (HR-SWI) human corneal elasticity; high-resolution shear wave imaging (HR-SWI)
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Chen, P.-Y.; Shih, C.-C.; Lin, W.-C.; Ma, T.; Zhou, Q.; Shung, K.K.; Huang, C.-C. High-Resolution Shear Wave Imaging of the Human Cornea Using a Dual-Element Transducer. Sensors 2018, 18, 4244.

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