Torsional wave elastography to assess the mechanical properties of the cornea
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AuthorTorres Pérez, Jorge; Faris al Azzawi, Inas H; Callejas Zafra, Antonio Manuel; Melchor Rodríguez, Juan Manuel; Rus Carlborg, Guillermo
Torres, J... [et al.]. Torsional wave elastography to assess the mechanical properties of the cornea. Sci Rep 12, 8354 (2022). [https://doi.org/10.1038/s41598-022-12151-2]
SponsorshipMinisterio de Educacion, Cultura y Deporte Grant DPI2017-83859-R DPI2014-51870-R UNGR15-CE-3664 EQC2018-004508-P; Spanish Government DTS15/00093 PI16/00339; Instituto de Salud Carlos III y Fondos Feder; Junta de Andalucia PI-0107-2017 PIN-0030-2017 IE2017-5537; MCIN/AEI - European Social Fund "Investing in your future" PRE2018-086085; Consejeria de economia, conocimiento, empresas y universidad SOMM17/6109/UGR B-TEP-026- IE2017-5537 P18-RT-1653; European Commission SOMM17/6109/UGR B-TEP-026- IE2017-5537 P18-RT-1653
Corneal mechanical changes are believed to occur before any visible structural alterations observed during routine clinical evaluation. This study proposed developing an elastography technique based on torsional waves (TWE) adapted to the specificities of the cornea. By measuring the displacements in the propagation plane perpendicular to the axis of the emitter, the effect of guided waves in platelike media was proven negligible. Ex vivo experiments were carried out on porcine corneal samples considering a group of control and one group of alkali burn treatment ( NH 4OH) that modified the mechanical properties. Phase speed was recovered as a function of intraocular pressure (IOP), and a Kelvin-Voigt rheological model was fitted to the dispersion curves to estimate viscoelastic parameters. A comparison with uniaxial tensile testing with thin-walled assumptions was also performed. Both shear elasticity and viscosity correlated positively with IOP, being the elasticity lower and the viscosity higher for the treated group. The viscoelastic parameters ranged from 21.33 to 63.17 kPa, and from 2.82 to 5.30 Pa s, for shear elasticity and viscosity, respectively. As far as the authors know, no other investigations have studied this mechanical plane under low strain ratios, typical of dynamic elastography in corneal tissue. TWE reflected mechanical properties changes after treatment, showing a high potential for clinical diagnosis due to its rapid performance time and paving the way for future in vivo studies.