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Michael Dattilo, Dillon Brown, C Ross Ethier; Comparison of Optic Nerve Sheath Material Properties in male and female rhesus macaque. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2677.
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© ARVO (1962-2015); The Authors (2016-present)
Although optic nerve sheath (ONS) changes have been described in several ophthalmic disorders, such as idiopathic intracranial hypertension (IIH), ONS biomechanical properties remain poorly understood, particularly in humans. Recently, inverse finite element modeling (iFEM) of human ONS has estimated that males have stiffer ONSs than females. Although several prior studies have described ONS biomechanical properties, the effect of gender was not assessed in those studies.
In preparation for testing human tissue, the ONS from one male and one female rhesus macaque (rONS) was dissected from the ON and placed in 1X PBS. A cylindrical sample of rONS (1 mm diameter), obtained using a biopsy punch, was placed on a MicroTester platform (CellScale, Ontario, Canada) in a temperature-controlled fluid bath (PBS at 37°C). Samples were pre-loaded with a compressive tare load of 500 uN, allowed to equilibrate, and then subjected to a 3-step stress relaxation protocol (5-15% compressive strain). Data from each step were analyzed independently using poroelastic theory to determine rONS through-plane compressive modulus and in-plane tensile modulus.
Female rONS compressive modulus was 4.7 kPa at 5% strain and increased to 8.8 kPa at 15% strain; tensile modulus was 35.1 kPa at 5% strain and increased to 116.9 kPa at 15% strain. Male rONS compressive modulus was 11.5 kPa at 5% strain and increased to 13.6 kPa at 15% strain; tensile modulus was 78.9 kPa at 5% strain and increased to 237.6 kPa at 15% strain.
Female rONS showed lower compressive and tensile moduli compared to male rONS, consistent with recently published iFEM data in humans. Although based on small sample numbers, this data suggests that human ONS biomechanical properties may also exhibit a gender difference. Further understanding of this difference may provide insights into the pathophysiology of IIH and may lead to the development of novel IIH treatments.
This is a 2021 ARVO Annual Meeting abstract.
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