TY - JOUR
T1 - Characterizing the collagen network structure and pressure-induced strains of the human lamina cribrosa
AU - Ling, Yik Tung Tracy
AU - Shi, Ran
AU - Midgett, Dan E.
AU - Jefferys, Joan L.
AU - Quigley, Harry A.
AU - Nguyen, Thao D.
N1 - Funding Information:
The authors thank the eye donors and their families who graciously provided ocular tissue to our project through Eversight. Supported by National Institutes of Health Grants EY01765 and EY02120, National Science Foundation CMMI Award 1727104, Brightfocus Foundation G2015132, Public Health Service Research Grants EY021500 and EY001765, Microscopy and Imaging Core Module, Wilmer Core Grant for Vision Research and the Croucher Foundation (YTTL). Disclosure: Y.T.T. Ling, None; R. Shi, None; D.E. Midgett, None; J.L. Jefferys, None; H.A. Quigley, None; T.D. Nguyen, None
Publisher Copyright:
© 2019 The Authors.
PY - 2019/6
Y1 - 2019/6
N2 - PURPOSE. The purpose of this study was to measure the 2D collagen network structure of the human lamina cribrosa (LC), analyze for the correlations with age, region, and LC size, as well as the correlations with pressure-induced strains. METHODS. The posterior scleral cups of 10 enucleated human eyes with no known ocular disease were subjected to ex vivo inflation testing from 5 to 45 mm Hg. The optic nerve head was imaged by using second harmonic generation imaging (SHG) to identify the LC collagen structure at both pressures. Displacements and strains were calculated by using digital volume correlation of the SHG volumes. Nine structural features were measured by using a custom Matlab image analysis program, including the pore area fraction, node density, and beam connectivity, tortuosity, and anisotropy. RESULTS. All strain measures increased significantly with higher pore area fraction, and all but the radial-circumferential shear strain (Erh) decreased with higher node density. The maximum principal strain (Emax) and maximum shear strain (Cmax) also increased with larger beam aspect ratio and tortuosity, respectively, and decreased with higher connectivity. The peripheral regions had lower node density and connectivity, and higher pore area fraction, tortuosity, and strains (except for Erh) than the central regions. The peripheral nasal region had the lowest Emax, Cmax, radial strain, and pore area fraction. CONCLUSIONS. Features of LC beam network microstructure that are indicative of greater collagen density and connectivity are associated with lower pressure-induced LC strain, potentially contributing to resistance to glaucomatous damage.
AB - PURPOSE. The purpose of this study was to measure the 2D collagen network structure of the human lamina cribrosa (LC), analyze for the correlations with age, region, and LC size, as well as the correlations with pressure-induced strains. METHODS. The posterior scleral cups of 10 enucleated human eyes with no known ocular disease were subjected to ex vivo inflation testing from 5 to 45 mm Hg. The optic nerve head was imaged by using second harmonic generation imaging (SHG) to identify the LC collagen structure at both pressures. Displacements and strains were calculated by using digital volume correlation of the SHG volumes. Nine structural features were measured by using a custom Matlab image analysis program, including the pore area fraction, node density, and beam connectivity, tortuosity, and anisotropy. RESULTS. All strain measures increased significantly with higher pore area fraction, and all but the radial-circumferential shear strain (Erh) decreased with higher node density. The maximum principal strain (Emax) and maximum shear strain (Cmax) also increased with larger beam aspect ratio and tortuosity, respectively, and decreased with higher connectivity. The peripheral regions had lower node density and connectivity, and higher pore area fraction, tortuosity, and strains (except for Erh) than the central regions. The peripheral nasal region had the lowest Emax, Cmax, radial strain, and pore area fraction. CONCLUSIONS. Features of LC beam network microstructure that are indicative of greater collagen density and connectivity are associated with lower pressure-induced LC strain, potentially contributing to resistance to glaucomatous damage.
KW - Beam network
KW - Digital volume correlation
KW - Inflation test
KW - Optic nerve head
KW - Pore area fraction
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U2 - 10.1167/iovs.18-25863
DO - 10.1167/iovs.18-25863
M3 - Article
C2 - 31157833
AN - SCOPUS:85067096691
SN - 0146-0404
VL - 60
SP - 2406
EP - 2422
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 7
ER -