Modeling and experimental investigation of electromechanical properties of scleral tissue; a CEM model using an anisotropic hyperelastic constitutive relation

Hatami-Marbini, Hamed; Mehr, Jafar Arash

doi:10.1007/s10237-022-01590-5

Cited by 4 publications

(20 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…9,[15][16][17] The density of GAGs is correlated with the density of fixed charges and could explain why we measured regionally different electroactive bending response. 11,12 Furthermore, the stiffness of sclera is different in the posterior, equatorial, and anterior regions. For example, the anterior sclera was found to be significantly stiffer than posterior and equatorial sclera.…”

Section: Discussionmentioning

confidence: 99%

“…The experimental setup was thoroughly discussed in our previous studies. 11,12 Briefly, the scleral strips were mounted inside a container between two carbon electrodes that were 5 cm apart, Figure 2. The container was filled with 0.15 M NaCl solution and the electrodes were connected a DC power supply (BK precision – CA, USA).…”

Section: Methodsmentioning

confidence: 99%

“…14 Finally, our numerical model predicted a strong correlation between the scleral ECM properties and its electroactive behavior. 11,12 Thus, we hypothesized here that scleral electroactive properties are regionally different. To test this hypothesis, we experimentally characterized the directional and regional electroactive response of the sclera.…”

Section: Introductionmentioning

confidence: 99%

“…We have recently showed that scleral strips bend toward the cathode when subjected to an external electric stimulation. 11,12 Moreover, we created a numerical model to investigate the parameters that are important in defining the electroactive response of sclera. The primary objective of the present research was to extend our previous work by characterizing the regional variation in scleral electroactive properties.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Regional differences in electroactive response of the sclera

Hatami-Marbini,

Mehr

2024

Proc Inst Mech Eng H

Self Cite

View full text Add to dashboard Cite

The sclera exhibits mechanical response when subjected to an external electric stimulation. The scleral electroactive response is a function of its charge density, mechanical properties, thickness, and strength of the applied electric voltage. The primary objective of the present work was to investigate the regional differences in the electroactive response of porcine sclera. To this end, we cut scleral strips in meridional directions from superior-temporal, superior-nasal, inferior-temporal, and inferior-nasal quadrants. In addition, we excised samples circumferentially from the posterior, equatorial, and anterior regions. The electroactive bending response of these samples was measured under 10 and 15 V in 0.15 M NaCl solution. The meridional samples were tested under two different configurations by clamping them either from their anterior or posterior end. It was observed that the scleral electroactive deformation increased with increasing the the electric voltage. Furthermore, regardless of the region from which meridional strips were excised, their electroactive response was considerably larger when they were clamped from their anterior end. Unlike meridional strips, the electroactive response of circumferential samples was significantly dependent on the location, that is, the average maximum bending angle of posterior samples was significantly larger than that of equatorial and anterior strips. The regionally different electroactive bending response of the sclera was discussed in terms of the variation in its biochemical and biomechanical properties throughout the eyeball.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Regional differences in electroactive response of the sclera

Hatami-Marbini,

Mehr

2024

Proc Inst Mech Eng H

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition, we must acknowledge that collagen uncrimping and stretch are not the only determinants of sclera biomechanical properties. Other potentially important factors include fiber architecture, density, anisotropy, and other components of the ground matrix, including elastin, glycosaminoglycan and proteoglycan content [48][49][50], and even hydration [1,2,11,31,[51][52][53][54]. These factors may contribute to the variability in how much the waviness changed relative to the amount of local strain experienced by any specific bundle, and to the stretch that each bundle was subjected to.…”

Section: Discussionmentioning

confidence: 99%

Stretch-Induced Uncrimping of Equatorial Sclera Collagen Bundles

Jan

Lee

Wallace

et al. 2022

Preprint

View full text Add to dashboard Cite

Stretch-induced collagen uncrimping underlies the nonlinear mechanical behavior of the sclera according to what is often called the process of recruitment. We recently reported experimental measurements of sclera collagen crimp and pressure-induced uncrimping. Our studies, however, were cross-sectional, providing statistical descriptions of crimp with no information on the effects of stretch on specific collagen bundles. Data on bundle-specific uncrimping is necessary to better understand the effects of macroscale input on the collagen microscale and tissue failure. Our goal in this project was to measure bundle-specific stretch-induced collagen uncrimping of sclera. Three goat eyes were cryosectioned sagittally (30 μm). Samples of equatorial sclera were isolated, mounted to a custom uniaxial stretcher and imaged with polarized light microscopy at various levels of clamp-to-clamp stretch until failure. At each stretch level, local strain was measured using image tracking techniques. The level of collagen crimping was determined from the bundle waviness, defined as the circular standard deviation of fiber orientation along a bundle. Eye-specific recruitment curves were then computed using eye-specific waviness at maximum stretch before sample failure to define fibers as recruited. Nonlinear mixed effect models were used to determine the associations of waviness to local strain and recruitment to clamp-to-clamp stretch. Waviness decreased exponentially with local strain (p<0.001), whereas bundle recruitment followed a sigmoidal curve with clamp-to-clamp stretch (p<0.001). Individual bundle responses to stretch varied substantially, but recruitment curves were similar across sections and eyes. In conclusion, uniaxial stretch caused measurable bundle-specific uncrimping, with the sigmoidal recruitment pattern characteristic of fiber-reinforced soft tissues.

show abstract

Stretch-Induced Uncrimping of Equatorial Sclera Collagen Bundles

Jan

Lee

Wallace

et al. 2022

Journal of Biomechanical Engineering

View full text Add to dashboard Cite

Recently we reported experimental measurements of sclera collagen crimp and pressure-induced uncrimping. However, our measurements were cross-sectional, providing statistical descriptions of crimp without information on the effects of stretch on specific collagen bundles. Data on bundle-specific uncrimping is necessary to understand the effects of macroscale input on the collagen microscale and tissue failure. Our goal in this project was to measure bundle-specific stretch-induced collagen uncrimping of sclera. Three goat eyes were cryosectioned sagittally (30µm). Samples of equatorial sclera were isolated, mounted to a custom uniaxial stretcher and imaged with polarized light microscopy at various levels of clamp-to-clamp stretch until failure. At each stretch level, local strain was measured using image tracking techniques. The level of collagen crimping was determined from the bundle waviness, defined as the circular standard deviation of fiber orientation along a bundle. Eye-specific recruitment curves were then computed using eye-specific waviness at maximum stretch before sample failure to define fibers as recruited. Nonlinear mixed effect models were used to determine the associations of waviness to local strain and recruitment to clamp-to-clamp stretch. Waviness decreased exponentially with local strain (p<0.001), whereas bundle recruitment followed a sigmoidal curve with clamp-to-clamp stretch (p<0.001). Individual bundle responses to stretch varied substantially, but recruitment curves were similar across sections and eyes. In conclusion, uniaxial stretch caused measurable bundle-specific uncrimping, with the sigmoidal recruitment pattern characteristic of fiber-reinforced soft tissues.

show abstract

Modeling and experimental investigation of electromechanical properties of scleral tissue; a CEM model using an anisotropic hyperelastic constitutive relation

Cited by 4 publications

References 80 publications

Regional differences in electroactive response of the sclera

Regional differences in electroactive response of the sclera

Stretch-Induced Uncrimping of Equatorial Sclera Collagen Bundles

Stretch-Induced Uncrimping of Equatorial Sclera Collagen Bundles

Contact Info

Product

Resources

About