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Theo G Seiler, Peng Shao, Marleen Engler, Eric Beck, Irene E Kochevar, Seok Hyun Yun; Corneal hydration and the relation to the biomechanical properties. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4333. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of corneal hydration on biomechanical properties of the cornea
Twenty-four rabbit corneas were divided into 4 groups of 6 eyes each. Corneas were excised and mounted into a Barron artificial anterior chamber. Then various corneal hydration steady states were achieved by applying different dextran T-500 concentrations in the anterior chamber, as well as on the corneal anterior surface. The solutions contained either 5, 10, 15 or 20% wt/wt dextran. Ultrasound pachymetry was used to measure central corneal thickness. Each eye was examined by a clinically-used Brillouin microscope to determine the Brillouin frequency shift of the anterior stroma in the central cornea within 2 mm from the pupil center. Afterwards, the central 10 mm corneal disk was excised and a 5mm-wide central strip was taken for uniaxial tensiometry. After tensiometry, the entire 10mm disk was dried using lyophilization and the dry weight was determined.
Greater corneal hydration lead to a significant thicker pachymetry. The forces measured at a strain of 9% were a factor of 2 higher (p<0.05) in corneas dehydrated with 20% dextran compared to those hydrated with 5% dextran. Taking the cross-section of the strip into consideration for the calculation of stress, this factor even increased up to 6-fold. Brillouin frequency shifts were different in all examined groups (p<0.05) and highly correlated to the results of the tensiometry as well as to corneal hydration levels. Dry weight did not differ significantly between the groups.
Corneal biomechanical properties are highly dependent on the level of corneal hydration. Therefore, it is essential to measure and control the hydration during ex vivo experiments.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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