Effects of age and diabetes on scleral stiffness

Coudrillier, Baptiste, Pijanka, Jacek, Jefferys, Joan, Sorensen, Thomas, Quigley, Harry A., Boote, Craig ORCID: https://orcid.org/0000-0003-0348-6547 and Nguyen, Thao D. 2015. Effects of age and diabetes on scleral stiffness. Journal of Biomechanical Engineering 137 (7) , pp. 1-10. 10.1115/1.4029986

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Abstract

The effects of diabetes on the collagen structure and material properties of the sclera are unknown but may be important to elucidate whether diabetes is a risk factor for major ocular diseases such as glaucoma. This study provides a quantitative assessment of the changes in scleral stiffness and collagen fiber alignment associated with diabetes. Posterior scleral shells from 5 diabetic donors and 7 non-diabetic donors were pressurized to 30 mmHg. Three-dimensional surface displacements were calculated during inflation testing using digital image correlation (DIC). After testing, each specimen was subjected to wide-angle x-ray scattering measurements of its collagen organization. Specimen-specific finite element models of the posterior scleras were generated from the experimentally measured geometry. An inverse finite element analysis was developed to determine the material properties of the specimens, i.e. matrix and fiber stiffness, by matching DIC-measured and finite element predicted displacement fields. Effects of age and diabetes on the degree of fiber alignment, matrix and collagen fiber stiffness, and mechanical anisotropy were estimated using mixed effects models accouting for spatial autocorrelation. Older age was associated with a lower degree of fiber alignment and larger matrix stiffness for both diabetic and non-diabetic scleras. However, the age-related increase in matrix stiffness was larger in diabetic specimens compared to non-diabetic controls and diabetic scleras had a significantly larger matrix stiffness. Older age was associated with an increase in collagen fiber stiffness for diabetic specimens only. Older age was associated with a decrease in mechanical anisotropy for non-diabetic scleras only. The interaction between age and diabetes was not significant for all outcomes. This study suggests that the age-related increase in scleral stiffness is accelerated in eyes with diabetes, which may have important implications in glaucoma.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Optometry and Vision Sciences
Publisher:	American Society of Mechanical Engineers (ASME)
ISSN:	0148-0731
Last Modified:	28 Oct 2022 08:38
URI:	https://orca.cardiff.ac.uk/id/eprint/71557

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