Regional Dynamic Viscoelastic Properties of Porcine Sclera

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2016-05

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The Ohio State University

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Abstract

The biomechanical properties of the posterior sclera are thought to be important in glaucoma susceptibility. Assessment of the posterior sclera biomechanics is currently unavailable in vivo but methods are being developed to characterize the biomechanical properties of the anterior portion of the eye. The objective of this study was to characterize the regional dynamic viscoelastic properties of porcine sclera to examine possible correlation between anterior and posterior sclera. Scleral strips were excised from the temporal region of the anterior and posterior portions of 30 porcine eyes within 24 hours post-mortem. The scleral strips were tested using a Rheometrics Systems Analyzer II in a humidity chamber at approximately 25 °C. A cyclic strain was applied to the strips and the cyclic stress output was recorded. A ramp test was also conducted. The biomechanical properties of the anterior and posterior scleral showed significant differences with a complex modulus of 1.67±0.63 and 0.35±0.1 MPa (p<0.001), a secant modulus at 1% strain of 1.17±0.67 and 0.17±0.06 MPa (p<0.001), and a dynamic viscosity of 0.04±0.015 and 0.008±0.033 (p<0.001). The thickness was also significantly different between the anterior and posterior sclera (0.99 mm and 1.58 mm, p<0.001) There was no correlation in thickness (p>0.25) or any biomechanical properties between the anterior and posterior sclera (p>0.82). These results provide insight to an interesting regional variance of the biomechanical properties of scleral tissue, which is not necessary proportional in the same eye. Future work will investigate scleral tissue microstructure to understand the structural basis of the mechanical difference from anterior to posterior eye.

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Biomechanical, Porcine, Sclera, Dynamic, Viscoelastic

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