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The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties

PURPOSE: The purpose of this study was to isolate the structural components of the ex vivo porcine iris tissue and to determine their biomechanical properties. METHODS: The porcine stroma and dilator tissues were separated, and their dimensions were assessed using optical coherence tomography (OCT)....

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Autores principales: Tan, Royston K. Y., Panda, Satish K., Braeu, Fabian A., Muralidharan, Arumugam R., Nongpiur, Monisha E., Chan, Anita S. Y., Aung, Tin, Najjar, Raymond P., Girard, Michaël J. A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Association for Research in Vision and Ophthalmology 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10561784/
https://www.ncbi.nlm.nih.gov/pubmed/37796489
http://dx.doi.org/10.1167/iovs.64.13.11
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author Tan, Royston K. Y.
Panda, Satish K.
Braeu, Fabian A.
Muralidharan, Arumugam R.
Nongpiur, Monisha E.
Chan, Anita S. Y.
Aung, Tin
Najjar, Raymond P.
Girard, Michaël J. A.
author_facet Tan, Royston K. Y.
Panda, Satish K.
Braeu, Fabian A.
Muralidharan, Arumugam R.
Nongpiur, Monisha E.
Chan, Anita S. Y.
Aung, Tin
Najjar, Raymond P.
Girard, Michaël J. A.
author_sort Tan, Royston K. Y.
collection PubMed
description PURPOSE: The purpose of this study was to isolate the structural components of the ex vivo porcine iris tissue and to determine their biomechanical properties. METHODS: The porcine stroma and dilator tissues were separated, and their dimensions were assessed using optical coherence tomography (OCT). The stroma underwent flow test (n = 32) to evaluate for permeability using Darcy's Law (ΔP = 2000 Pa, A = 0.0391 mm(2)), and both tissues underwent stress relaxation experiments (ε = 0.5 with initial ramp of δε = 0.1) to evaluate for their viscoelastic behaviours (n = 28). Viscoelasticity was characterized by the parameters β (half width of the Gaussian distribution), τ(m) (mean relaxation time constant), E(0) (instantaneous modulus), and E(∞) (equilibrium modulus). RESULTS: For the stroma, the hydraulic permeability was 9.49 ± 3.05 × 10(−6) mm(2)/Pa · s, and the viscoelastic parameters were β = 2.50 ± 1.40, and τ(m) = 7.43 ± 4.96 s, with the 2 moduli calculated to be E(0) = 14.14 ± 6.44 kPa and E(∞) = 6.08 ± 2.74 kPa. For the dilator tissue, the viscoelastic parameters were β = 2.06 ± 1.33 and τ(m) = 1.28 ± 1.27 seconds, with the 2 moduli calculated to be E(0) = 9.16 ± 3.03 kPa and E(∞) = 5.54 ± 1.98 kPa. CONCLUSIONS: We have established a new protocol to evaluate the biomechanical properties of the structural layers of the iris. Overall, the stroma was permeable and exhibited smaller moduli than those of the dilator muscle. An improved characterization of iris biomechanics may form the basis to further our understanding of angle closure glaucoma.
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spelling pubmed-105617842023-10-10 The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties Tan, Royston K. Y. Panda, Satish K. Braeu, Fabian A. Muralidharan, Arumugam R. Nongpiur, Monisha E. Chan, Anita S. Y. Aung, Tin Najjar, Raymond P. Girard, Michaël J. A. Invest Ophthalmol Vis Sci Glaucoma PURPOSE: The purpose of this study was to isolate the structural components of the ex vivo porcine iris tissue and to determine their biomechanical properties. METHODS: The porcine stroma and dilator tissues were separated, and their dimensions were assessed using optical coherence tomography (OCT). The stroma underwent flow test (n = 32) to evaluate for permeability using Darcy's Law (ΔP = 2000 Pa, A = 0.0391 mm(2)), and both tissues underwent stress relaxation experiments (ε = 0.5 with initial ramp of δε = 0.1) to evaluate for their viscoelastic behaviours (n = 28). Viscoelasticity was characterized by the parameters β (half width of the Gaussian distribution), τ(m) (mean relaxation time constant), E(0) (instantaneous modulus), and E(∞) (equilibrium modulus). RESULTS: For the stroma, the hydraulic permeability was 9.49 ± 3.05 × 10(−6) mm(2)/Pa · s, and the viscoelastic parameters were β = 2.50 ± 1.40, and τ(m) = 7.43 ± 4.96 s, with the 2 moduli calculated to be E(0) = 14.14 ± 6.44 kPa and E(∞) = 6.08 ± 2.74 kPa. For the dilator tissue, the viscoelastic parameters were β = 2.06 ± 1.33 and τ(m) = 1.28 ± 1.27 seconds, with the 2 moduli calculated to be E(0) = 9.16 ± 3.03 kPa and E(∞) = 5.54 ± 1.98 kPa. CONCLUSIONS: We have established a new protocol to evaluate the biomechanical properties of the structural layers of the iris. Overall, the stroma was permeable and exhibited smaller moduli than those of the dilator muscle. An improved characterization of iris biomechanics may form the basis to further our understanding of angle closure glaucoma. The Association for Research in Vision and Ophthalmology 2023-10-05 /pmc/articles/PMC10561784/ /pubmed/37796489 http://dx.doi.org/10.1167/iovs.64.13.11 Text en Copyright 2023 The Authors https://creativecommons.org/licenses/by-nc-nd/4.0/This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
spellingShingle Glaucoma
Tan, Royston K. Y.
Panda, Satish K.
Braeu, Fabian A.
Muralidharan, Arumugam R.
Nongpiur, Monisha E.
Chan, Anita S. Y.
Aung, Tin
Najjar, Raymond P.
Girard, Michaël J. A.
The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title_full The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title_fullStr The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title_full_unstemmed The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title_short The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties
title_sort structural layers of the porcine iris exhibit inherently different biomechanical properties
topic Glaucoma
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10561784/
https://www.ncbi.nlm.nih.gov/pubmed/37796489
http://dx.doi.org/10.1167/iovs.64.13.11
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