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Depth-Dependent Changes in Collagen Organization in the Human Peripapillary Sclera

DOI: 10.1371/journal.pone.0118648 DOI Help
PMID: 25714753 PMID Help

Authors: Jacek Pijanka (Cardiff University) , Martin Spang (Cardiff University) , Thomas Sorensen (Diamond Light Source) , Jun Liu (Department of Biomedical Engineering, The Ohio State University) , Thao Nguyen (Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland,) , Harry A. Quigley (Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore) , Craig Boote (University of Cardiff) , Che Connon (University of Reading)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Plos One , VOL 10 (2)

State: Published (Approved)
Published: February 2015
Diamond Proposal Number(s): 8443

Open Access Open Access

Abstract: Purpose The collagen structure of the human peripapillary sclera plays a significant role in determining optic nerve head (ONH) biomechanics, and is therefore of interest in the study of glaucoma. The aim of the current work was to map the anisotropic collagen structure of the normal human peripapillary sclera as a function of tissue depth. Methods Wide-angle x-ray scattering was used to quantify collagen fibril orientation at 0.5mm intervals across six 150μm-thick serial sections through the peripapillary sclera of eight normal European-derived human eyes. Two structural parameters were measured: 1) the relative number of fibrils preferentially aligned at a given angle within the tissue plane, 2) the degree of collagen alignment (anisotropy). Results The inner-most one-third of the peripapillary scleral stroma (nearest to the choroid) was characterised by collagen fibrils either randomly arranged or preferentially aligned radially with respect to the ONH. In contrast, the outer two-thirds of the tissue was dominated by a circumferential arrangement of collagen encircling the ONH. In all tissue regions the degree of collagen anisotropy peaked in the mid-stroma and progressively decreased towards the tissue surfaces, with the largest depth variations occurring in the inferior-nasal quadrant, and the smallest occurring in the superior-nasal quadrant. Conclusions Significant, region-specific variations in collagen structure are present in the human peripapillary sclera as a function of depth. In normal eyes, the circumferential collagen fibril architecture is most prominent in the outer two-thirds of the stroma, possibly as a mechanical adaption to more effectively support the lamina cribrosa at the level of its insertion into the scleral canal wall.

Subject Areas: Medicine

Instruments: I02-Macromolecular Crystallography