An ultrasonic technique for the measurement of the elastic moduli of human cornea

Wang, Hsi-Chun; Prendiville, Paul L.; McDonnell, Peter J.; Chang, W. V.

doi:10.1016/s0021-9290(96)80017-0

Cited by 69 publications

(22 citation statements)

References 15 publications

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“…It was found that apical corneal displacement after an intraocular pressure change equivalent to that occurring in vivo due to the cardiac cycle decreased in a linear manner with age from approximately 0.25 MPa at age 20 to 0.5 MPa at age 100. These values are toward the lower end of previously published values of human corneal Young's modulus, which have varied from 0.15 to 57 MPa, 7,22,23,[27][28][29][30][31][32][33][34] a range that is greater than is physiologically plausible. Studies that have used strip extensometry or ultrasonography have given rise to higher values 27,28,30 -35 while studies inflating intact globes to greater than physiological pressures determined values more closely related to those of the present study.…”

Section: Discussionmentioning

confidence: 64%

“…43 In common with all studies that have used thin-shell theory to analyze the mechanical response of the cornea, it was necessary to regard it as a purely elastic, mechanically isotropic, rotationally symmetric part sphere of uniform thickness that is fixed at the limbus. 7,44 Although attempts have been made to model the cornea in a more complex way during finite element analysis, the uncertainty surrounding the true values of corneal characteristics such Young's modulus 7,22,23,[27][28][29][30][31][32][33][34][35] and Poisson ratio 45,46 means that this process also requires assumptions to be made that can greatly affect the results obtained. For these reasons the thin shell model is generally accepted to be a reasonable approximation, especially when surgical incisions are not considered.…”

Section: Discussionmentioning

confidence: 99%

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Age-Related Differences in the Elasticity of the Human Cornea

Cartwright

Tyrer

Marshall

2011

Invest. Ophthalmol. Vis. Sci.

156

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Age-Related Differences in the Elasticity of the Human Cornea

Cartwright

Tyrer

Marshall

2011

Invest. Ophthalmol. Vis. Sci.

156

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show abstract

“…The estimated values of Young's moduli (porcine flap: 2.29 MPa; rabbit flap: 1.98 MPa) fall within the ranges reported in literature, although those vary over more than two orders of magnitude depending on the study. 1,2,5,6,8,13,[18][19][20] As a reference, in vitro strip extensiometry experiments estimated a Young's modulus of 11.1 MPa for rabbit corneas and 1.5 MPa for porcine corneas.…”

Section: Discussionmentioning

confidence: 99%

Corneal Biomechanical Properties from Two-Dimensional Corneal Flap Extensiometry: Application to UV-Riboflavin Cross-Linking

Kling

Ginis

Marcos

2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Corneal biomechanical properties are usually measured by strip extensiometry or inflation methods. We developed a two-dimensional (2D) flap extensiometry technique, combining the advantages of both methods, and applied it to measure the effect of UV-Riboflavin cross-linking (CXL).METHODS. Corneal flaps (13 pig/8 rabbit) from the deepithelialized anterior stroma (96 lm) were mounted on a custom chamber, consisting of a BK7 lens, a reflective retina, and two reservoirs (filled with Riboflavin and silicone oil). Stretching the corneal flap during five pressure increase/ decrease cycles (0-30 mm Hg) changed the refractive power of the system, whose Zernike aberrations were monitored with a ray-tracing aberrometer. Porcine flaps were used to test the system. Rabbits were treated with CXL unilaterally in vivo following standard clinical procedures. Flaps were measured 1 month postoperatively. An analytical model allowed estimating Young's modulus from the change in surface (strain) and pressure (stress). Confocal microscopy examination was performed before, and at different times after CXL. CONCLUSIONS. 2D flap extensiometry allows estimating corneal elasticity in vitro. The measurements are spatially resolved in depth, minimize the effects of corneal hydration, and preserve the integrity of the cornea. The method proved the efficacy of CXL in increasing corneal rigidity after 1 month in rabbits. (Invest Ophthalmol Vis Sci. 2012;53:5010-5015)

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“…Strain elastography, that measures the modification in the length of the tissue during a continuous compression and decompression of the skin, was the first modality to have a potential use [2,3]. Shear wave elastography (SWE), which calculates shear Young's elastic modulus, via the measurement of the lateral propagation velocity of the shear waves after an ultrasound focused beam generated by the transducer, will be coming at a later date [4] and is still being developed for clinical use.…”

Section: Introductionmentioning

confidence: 99%

Reliability of quantitative point shear-wave ultrasound elastography on vastus medialis muscle and quadriceps and patellar tendons

et al. 2019

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Aim: The aim of this work was to evaluate the reliability of pSWE in assessing the stiffness of the vastus medialis muscle and of the quadriceps and patellar tendons.Material and methods: For this purpose, 18 subjects (9 males and 9 females of 57±22 years) in good clinical conditions were included in this study. pSWE examination was conducted by a unique expert operator with more than ten years of experience in musculoskeletal ultrasound. Two sets of five measurements for each muscle and tendon district were bilaterally performed at the same manner, at least fifteen minutes apart. The mean value of the measurements of each set was statistically compared with that of the other set.Results: No significant differences were found comparing the mean value of the measurements of the two sets of evaluation performed in muscle and tendon areas (vastus medialis muscle: p=0.285; quadriceps tendon: p=0.979; patellar tendon: p=0.187). The intraclass correlation coefficient was excellent for all areas (vastus medialis muscle: 0.969; quadriceps and patellar tendons: 0.995 and 0.989, respectively).Conclusion: The pSWE technique demonstrated that it was a reliable method for measuring stiffness in vastus medialis muscle and quadriceps and patellar tendon in subjects who had undergone orthopedic surgery. This opens the possibility of many applications in monitoring stiffness before and after surgery and during rehabilitation.

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An ultrasonic technique for the measurement of the elastic moduli of human cornea

Cited by 69 publications

References 15 publications

Age-Related Differences in the Elasticity of the Human Cornea

Age-Related Differences in the Elasticity of the Human Cornea

Corneal Biomechanical Properties from Two-Dimensional Corneal Flap Extensiometry: Application to UV-Riboflavin Cross-Linking

Reliability of quantitative point shear-wave ultrasound elastography on vastus medialis muscle and quadriceps and patellar tendons

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