Collagen Microstructural Factors Influencing Optic Nerve Head Biomechanics

Zhang, Liang; Albon, Julie; Jones, Hannah; Gouget, Cecile L. M.; Ethier, C. Ross; Goh, James Cho‐Hong; Girard, M

doi:10.1167/iovs.14-15734

Cited by 91 publications

(111 citation statements)

References 61 publications

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“…Lamina cribosas with radially oriented capillaries at the peripheral region had higher average oxygen concentration than those with isotropic or circumferential configurations. Note that human LCs naturally exhibit a radial arrangement of the microcapillaries at the periphery 31 and any deviations from such an arrangement (possible through focal defects 55 ) may contribute to the development of OAG.…”

Section: Discussionmentioning

confidence: 99%

“…7 To mimic such heterogeneity, all our networks were subdivided into nine regions ( LC Anisotropy. In its periphery, the LC was either considered: (1) anisotropic with a radial arrangement of the LC beams (and thus capillaries) as observed in humans and primates, 31 (2) isotropic (also observed in humans), 31 or (3) anisotropic with a circumferential arrangement (hypothetical scenario). For our LC network generator algorithm, the anisotropy input parameter (r) was defined as the ellipse major-to-minor axis ratio minus 1.…”

Section: Generation Of Artificial Lc Microcapillary Networkmentioning

confidence: 99%

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Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Chuangsuwanich

Birgersson

Thiéry

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To identify and rank the lamina cribrosa (LC) morphologic factors that influence LC microcapillary hemodynamics and oxygen concentrations using computational fluid dynamics (CFD).METHODS. We generated 12,000 'artificial' LC microcapillary networks and predicted blood flow velocities and oxygen concentrations within the microcapillaries using CFD. Across models, we varied the average pore size of the LC (5500 6 2400 lm 2 ), the microcapillary arrangement (radial, isotropic, or circumferential), the LC diameter (1.9 6 0.3 mm), the inferior-superior curvature (340 6 116 m À1 ), and the nasal-temporal curvature (À78 6 130 m À1 ). We assumed that blood flow originated from the Circle of Zinn-Haller, fed the LC uniformly at its periphery, and was drained into the central retinal vein. Arterial (50 6 6 mm Hg) and venous (17.7 6 6 mm Hg) pressures were applied as boundary conditions and were also varied within our simulations. Finally, we performed linear regression analysis to rank the influence of each factor on LC hemodynamics and oxygen concentrations. RESULTS.The factors influencing LC hemodynamics and oxygen concentrations the most were: LC diameter, arterial pressure, and venous pressure, and to a lesser extent: the microcapillary arrangement (anisotropy) and nasal-temporal curvature. Lamina cribrosa pore size and superior-inferior curvature had almost no impact. Specifically, we found that LCs with a smaller diameter, a radial arrangement of the microcapillaries, an elevated arterial pressure and a decreased venous pressure had higher oxygen concentrations across their networks.CONCLUSION. This study described LC hemodynamics using a computational modeling approach. Our study may provide clinically relevant information for the understanding of ischemia-induced neuronal cell death in optic neuropathies.

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Section: Discussionmentioning

confidence: 99%

Section: Generation Of Artificial Lc Microcapillary Networkmentioning

confidence: 99%

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Chuangsuwanich

Birgersson

Thiéry

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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“…1) to account for the circumferential alignment of collagen fibers within the scleral flange and around the scleral canal. 22 Collagen fibers in other scleral regions were organized randomly. The collagen fibers in the LC were more isotropic than in the sclera, but organized along the radial direction (from the central vessel trunk to the scleral canal).…”

Section: Materials Stiffness Of the Reconstructed Eye Tissuesmentioning

confidence: 99%

Predictions of Optic Nerve Traction Forces and Peripapillary Tissue Stresses Following Horizontal Eye Movements

Wang

Fisher

Miléa

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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“…Within this paradigm, IOP-related stresses and strains are thought to affect axoplasmic transport (at the level of the LC), LC hemodynamics, oxygen and nutrient distributions, and cellular activity within the ONH. 3 The compliance of the ONH to acute IOP elevation has been studied using experimental [4][5][6][7][8][9][10][11][12][13][14] and computational models, [15][16][17][18][19] and the findings have varied. Studies using either ex vivo or histologic specimens showed that the LC bowed posteriorly in response to acute IOP elevation.…”

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confidence: 99%

Shape Changes of the Anterior Lamina Cribrosa in Normal, Ocular Hypertensive, and Glaucomatous Eyes Following Acute Intraocular Pressure Elevation

Tun

Thakku

Png

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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Citation: Tun TA, Thakku SG, Png O, et al. Shape changes of the anterior lamina cribrosa in normal, ocular hypertensive, and glaucomatous eyes following acute intraocular pressure elevation. Invest Ophthalmol Vis Sci. 2016;57:4869-4877. DOI:10.1167/ iovs.16-19753 PURPOSE. The purpose of this study was to estimate and compare changes in anterior lamina cribrosa (LC) morphology in normal, ocular hypertensive (OHT), and glaucomatous eyes following acute elevations in intraocular pressure (IOP). METHODS. The optic nerve heads (ONHs) of 97 subjects (17 OHT, 19 primary open-angle glaucoma [POAG], 31 primary angle-closure glaucoma [PACG], and 30 normal subjects) were imaged using optical coherence tomography (OCT). Intraocular pressure was raised twice by applying forces to the anterior sclera, using an ophthalmodynamometer. After each IOP elevation, IOP was held constant and measured; each ONH was rescanned with OCT. In each OCT volume, the anterior LC was enhanced, delineated, and its global shape index (GSI) calculated and compared across groups.RESULTS. The baseline IOP was 17.5 6 3.5 mm Hg and was increased to 38 6 5.9 mm Hg and then to 46.5 6 5.9 mm Hg. At the first IOP increment, mean GSI was significantly smaller than that at baseline in normal subjects and glaucoma subjects (P < 0.05) but not in OHT subjects (P ¼ 0.12). For the second IOP increment, the mean GSI was significantly smaller than that at baseline in normal subjects and in OHT eyes (P < 0.05). After adjusting for age, sex, and baseline IOP, the LC of POAG eyes was found to be significantly more posteriorly curved than that of normal subjects (P ¼ 0.04).CONCLUSIONS. Acute IOP elevations altered anterior LC shape in a complex nonlinear fashion. The LC of POAG eyes was more cupped following acute IOP elevations compared to that of normal subjects.

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Collagen Microstructural Factors Influencing Optic Nerve Head Biomechanics

Cited by 91 publications

References 61 publications

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Predictions of Optic Nerve Traction Forces and Peripapillary Tissue Stresses Following Horizontal Eye Movements

Shape Changes of the Anterior Lamina Cribrosa in Normal, Ocular Hypertensive, and Glaucomatous Eyes Following Acute Intraocular Pressure Elevation

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