Characterization of hyperelastic mechanical properties for youth corneal anterior central stroma based on collagen fibril crimping constitutive model

Liu, Taiwei; Shen, Min; Huang, Laixin; Xiang, Yaoqi; Li, Hongxun; Zhang, Yan; Wang, Yan

doi:10.1016/j.jmbbm.2019.103575

Cited by 20 publications

(5 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, in the uniaxial tensile test of corneal strips, the stress–strain relationship should be

, where

are the initial stress and strain of the specimen, respectively. In many studies, the zero stress state has been taken as the initial state, i.e.,

and

are zero ( Elsheikh et al, 2010 ; Liu et al, 2020a ; Liu et al, 2020b ). According to the Laplace formula, the corneal stress under IOP is

( p , r , and t are the IOP, corneal radius, and corneal thickness, respectively); if the IOP is 16 mmHg, corneal radius and corneal thickness are 6 and 0.57 mm, respectively, the tensile stress of the cornea is 0.0112 MPa under IOP.…”

Section: Discussionmentioning

confidence: 99%

“…Considering the time dependence of corneal stress responding to any loads, a visco-hyperelastic model based on strain energy function has been shown to describe corneal nonlinear and viscoelastic properties ( Liu et al, 2020a ; Su et al, 2015 ; Whitford et al, 2018 ). As one of well-known isotropic strain energy functions, the Ogden model can better describe the nonlinear stress–strain relationship of the cornea ( Bao et al, 2017 ; Bao et al, 2018 ; Joda et al, 2016 ; Lago et al, 2015 ; Maklad et al, 2019 ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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

Zhang

Tian

et al. 2021

Front. Bioeng. Biotechnol.

View full text Add to dashboard Cite

Purpose: The aim of this study was to provide a method to determine corneal nonlinear viscoelastic properties based on the output data of corneal visualization Scheimpflug technology (Corvis ST).Methods: The Corvis ST data from 18 eyes of 12 healthy humans were collected. Based on the air-puff pressure and the corneal displacement from the Corvis ST test of normal human eyes, the work done by the air-puff attaining the whole corneal displacement was obtained. By applying a visco-hyperelastic strain energy density function of the cornea, in which the first-order Prony relaxation function and the first-order Ogden strain energy were employed, the corneal strain energy during the Corvis ST test was calculated. Then the work done by the air-puff attaining the whole corneal displacement was completely regarded as the strain energy of the cornea. The identification of the nonlinear viscoelastic parameters was carried out by optimizing the sum of difference squares of the work and the strain energy using the genetic algorithm.Results: The visco-hyperelastic model gave a good fit to the data of corneal strain energy with time during the Corvis ST test (R2 > 0.95). The determined Ogden model parameter μ ranged from 0.42 to 0.74 MPa, and α ranged from 32.76 to 55.63. The parameters A and τ in the first-order Prony function were 0.09–0.36 and 1.21–1.95 ms, respectively.Conclusion: It is feasible to determine the corneal nonlinear viscoelastic properties based on the corneal contour information and air-puff pressure of the Corvis ST test.

show abstract

“…For example, in the uniaxial tensile test of corneal strips, the stress–strain relationship should be

, where

are the initial stress and strain of the specimen, respectively. In many studies, the zero stress state has been taken as the initial state, i.e.,

and

are zero ( Elsheikh et al, 2010 ; Liu et al, 2020a ; Liu et al, 2020b ). According to the Laplace formula, the corneal stress under IOP is

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

Zhang

Tian

et al. 2021

Front. Bioeng. Biotechnol.

View full text Add to dashboard Cite

show abstract

“…Corneal collagen fibrils were the load-bearing microstructures of the cornea. The corneal biomechanical properties are affected by the status of collagen fibrils [ 37 – 39 ]. Our results showed that the density of collagen fibrils increased, and the fibrils became thinner compared their control group at the 3rd month after operation ( P < 0.05, Fig.…”

Section: Discussionmentioning

confidence: 99%

Time-varying regularity of changes in biomechanical properties of the corneas after removal of anterior corneal tissue

et al. 2021

View full text Add to dashboard Cite

Background The corneal biomechanical properties with the prolongation of time after corneal refractive surgery are important for providing a mechanical basis for the occurrence of clinical phenomena such as iatrogenic keratectasia and refractive regression. The aim of this study was to explore the changes of corneal elastic modulus, and stress relaxation properties from the 6-month follow-up observations of rabbits after a removal of anterior corneal tissue in simulation to corneal refractive surgery. Methods The anterior corneal tissue, 6 mm in diameter and 30–50% of the original corneal thickness, the left eye of the rabbit was removed, and the right eye was kept as the control. The rabbits were normally raised and nursed for 6 months, during which corneal morphology data, and both of corneal hysteresis (CH) and corneal resistance factor (CRF) were gathered. Uniaxial tensile tests of corneal strips were performed at months 1, 3, and 6 from 7 animals, and corneal collagen fibrils were observed at months 1, 3, and 6 from 1 rabbit, respectively. Results Compared with the control group, there were statistical differences in the curvature radius at week 2 and month 3, and both CH and CRF at months 1, 2, and 6 in experiment group; there were statistical differences in elastic modulus at 1, 3, and month 6, and stress relaxation degree at month 3 in experiment group. The differences in corneal elastic modulus, stress relaxation degree and the total number of collagen fibrils between experiment and control groups varied gradually with time, and showed significant changes at the 3rd month after the treatment. Conclusions Corneas after a removal of anterior corneal tissue undergo dynamic changes in corneal morphology and biomechanical properties. The first 3 months after treatment could be a critical period. The variation of corneal biomechanical properties is worth considering in predicting corneal deformation after a removal of anterior corneal tissue.

show abstract

“…During one loading process, nonload section is located at the beginning of the curve caused by the initial bending of the corneal strips. The zero-load length ( l 0 ) was cut using the formulation ( Liu et al, 2020 )

where d is the average force in the zero-load length cause by placing the corneal strips.…”

Section: Methodsmentioning

confidence: 99%

Measuring Human Corneal Stromal Biomechanical Properties Using Tensile Testing Combined With Optical Coherence Tomography

Song

Shen

et al. 2022

Front. Bioeng. Biotechnol.

View full text Add to dashboard Cite

Purpose: To investigate the ex vivo elastic modulus of human corneal stroma using tensile testing with optical coherence tomography (OCT) imaging and its correlation with in vivo measurements using corneal visualization Scheimpflug technology.Methods: Twenty-four corneal specimens extracted from stromal lenticules through small incision lenticule extraction were cut into strips for uniaxial tensile tests. In vivo corneal biomechanical responses were evaluated preoperatively using the corneal visualization Scheimpflug technology (CorVis ST). The correlation of the elastic modulus with clinical characteristics and dynamic corneal response parameters were analyzed using Spearman’s correlation analysis.Results: The mean low strain tangent modulus (LSTM) of the human corneal stroma was 0.204 ± 0.189 (range 0.010–0.641) MPa, and high strain tangent modulus (HSTM) 5.114 ± 1.958 (range 2.755–9.976) MPa. Both LSTM (r = 0.447, p = 0.029) and HSTM (r = 0.557, p = 0.005) were positively correlated with the stress-strain index (SSI). LSTM was also positively correlated with the A1 deflection length (r = 0.427, p = 0.037) and A1 deflection area (r = 0.441, p = 0.031). HSTM was positively correlated with spherical equivalent (r = 0.425, p = 0.038).Conclusions: The correlation of corneal elastic modulus with A1 deflection parameters and SSI may indicate a relationship between these parameters and tissue elasticity. The HSTM decreased with the degree of myopia. Combining tensile test with OCT may be a promising approach to assess corneal biomechanical properties.

show abstract

Characterization of hyperelastic mechanical properties for youth corneal anterior central stroma based on collagen fibril crimping constitutive model

Cited by 20 publications

References 76 publications

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

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

Time-varying regularity of changes in biomechanical properties of the corneas after removal of anterior corneal tissue

Measuring Human Corneal Stromal Biomechanical Properties Using Tensile Testing Combined With Optical Coherence Tomography

Contact Info

Product

Resources

About