Assessment of corneal viscoelasticity using elastic wave optical coherence elastography

Abstract

The corneal viscoelasticity have great clinical significance, such as the early diagnosis of keratoconus. In this work, an analysis method which utilized the elastic wave velocity, frequency and energy attenuation to assess the corneal viscoelasticity is presented. Using phase‐resolved optical coherence tomography, the spatial‐temporal displacement map is derived. The phase velocity dispersion curve and center frequency are obtained by transforming the displacement map into the wavenumber‐frequency domain through the 2D fast Fourier transform (FFT). The shear modulus is calculated through Rayleigh wave equation using the phase velocity in the high frequency. The normalized energy distribution is plotted by transforming the displacement map into the spatial‐frequency domain through the 1D FFT. The energy attenuation coefficient is derived by exponential fitting to calculate the viscous modulus. Different concentrations of tissue‐mimicking phantoms and porcine corneas are imaged to validate this method, which demonstrates that the method has the capability to assess the corneal viscoelasticity.

Exploring the Biomechanical Properties of the Human Cornea In Vivo Based on Corvis ST

“…For abnormal cornea, corneal viscoelasticity plays an important role ( Vellara and Patel, 2015 ) in the maintenance of corneal morphology under long-term IOP. Keratoconus, a common clinical disease characterized by progressive corneal dilation, is highly related to corneal viscoelasticity ( Vellara and Patel, 2015 ; Jin et al, 2020 ; Rahmati et al, 2021 ). This study gives a more comprehensive understanding of corneal biomechanical properties from the test of cornea in vivo .…”

Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

“…Viscosity assessment in shear wave OCE is in its early phase of development. Proposed methods used shear wave frequency dispersion [343][344][345][346], storage and loss moduli using a rheological model [347], and the elastic wave attenuation [345].…”

Viscoelastic properties' characterization of corneal stromal models using non‐contact surface acoustic wave optical coherence elastography (SAW‐OCE)

“…However, the phase velocity of Lamb wave converges to the surface wave velocity (Rayleigh) in the high frequency of asymmetric mode A 0 for the case of sample with air-medium (free) boundaries [35]. Previous studies [57,65] characterized corneal viscoelasticity based on this elastic wave theory to calculate Lamb wave velocity in a high-frequency (greater than central frequency) through a Rayleigh wave equation. Thus, even though the dominating wave changed to Lamb wave due to the reduced thickness of the hydrogels, the viscoelastic parameters were still able to be estimated by fitting the phase velocity in the high-frequency range into the Rayleigh wave dispersion equation.…”

“…Compared to other OCE methods, such as ultrasound-induced wave-based OCE [55,56] or piezoelectric transducer-induced wave-based OCE [57,58], air-pulseinduced wave-based OCE is a totally non-contact detection approach, which is suitable to realize continuous biomechanical measurements of samples.…”