Nonlinear fourth-order elastic characterization of the cornea using torsional wave elastography
Antonio Callejas1,2, Inas Faris3,4, Jorge Torres3,4
1Ultrasonics Lab (TEP-959), Department of Structural Mechanics, University of Granada, Granada, 18071, Spain. acallejas@ugr.es.
Physical and Engineering Sciences in Medicine
|August 29, 2023
Summary
This study introduces a new method using torsional wave elastography (TWE) to measure nonlinear corneal properties. The technique successfully differentiates healthy corneas from damaged ones, aiding in disease detection.
Area of Science:
- Biomechanical Engineering
- Ophthalmology
- Materials Science
Background:
- Accurate measurement of corneal mechanical nonlinear properties is challenging due to methodological inconsistencies.
- Existing models struggle to predict corneal behavior under varying conditions.
Purpose of the Study:
- To develop a procedure for reconstructing nonlinear fourth-order elastic properties of the cornea.
- To validate the diagnostic capability of the proposed method using simulated pathological conditions.
Main Methods:
- Utilized torsional wave elastography (TWE) and a mathematical model based on Hamilton et al.'s theory.
- Studied non-treated (control) and ammonium hydroxide-treated (damaged) cornea samples (n=7 each).
- Measured shear wave speed by increasing intraocular pressure (IOP) from 5 to 25 mmHg.
Main Results:
- Demonstrated a nonlinear relationship between shear wave speed and IOP, increasing with higher IOP.
- Observed higher shear wave speeds in control corneas compared to treated corneas.
- Found significant differences in Lamé parameter (λ), third-order elastic constant (A), and fourth-order elastic constant (D) between groups (p<0.05).
Conclusions:
- The proposed TWE procedure can effectively distinguish between healthy and damaged corneas.
- This technique shows promise for detecting diseases linked to IOP alterations, such as corneal burns, glaucoma, and ocular hypertension.
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