Measuring mechanical wave speed, dispersion, and viscoelastic modulus of the cornea using optical coherence elastography

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.

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

“…The wave energy attenuation coefficient is associated with the viscoelasticity of the medium and angular frequency using the following equations :

α ((), ω) = ω \frac{\sqrt{ρ (β - 1)}}{\sqrt{2 μ_{1} β^{2}}},

β = \sqrt{1 + {(\frac{ωζ}{μ_{1}})}^{2}},

where α ( ω ) is the energy attenuation coefficient.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessment of corneal viscoelasticity using elastic wave optical coherence elastography

Jin

Zhou

Shen

et al. 2019

Relaxation time constant based optical coherence elastography

Zhang

Huang

2020

In vivo noninvasive measurement of spatially resolved corneal elasticity in human eyes using Lamb wave optical coherence elastography

Jin

Chen

Dai

et al. 2020

Current elastography techniques are limited in application to accurately assess spatially resolved corneal elasticity in vivo for human eyes. The air‐puff optical coherence elastography (OCE) with an eye motion artifacts correction algorithm is developed to distinguish the in vivo cornea vibration from the eye motion and visualize the Lamb wave propagation clearly in healthy subjects. Based on the Lamb wave model, the phase velocity dispersion curve in the high‐frequency is calculated to obtain spatially resolved corneal elasticity accurately with high repeatability. It is found that the corneal elasticity has regional variations and is correlated with intraocular pressure, which suggests that the method has the potential to provide noninvasive measurement of spatially resolved corneal elasticity in clinical practice.