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Massimo Antonio Fazio, Vincent Libertiaux, Hongli Yang, Howard Lockwood, Juan Reynaud, Claude F Burgoyne, J Crawford C Downs; Addition of Laminar Beams Into the Lamina Cribrosa Structure in Experimental Glaucoma. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6154.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the regional differences in the density, orientation, degree of anisotropy, thickness, and number of beams through the thickness of the lamina cribrosa in nonhuman primate (NHP) eyes with EG compared to their normal contralateral controls.
Four bilateral normal and 9 NHPs with induced unilateral glaucoma were sacrificed at the onset of early EG (10-30% axon loss).2,3 ONHs underwent 3D reconstruction1,3 The images are then aligned and stacked into a digital 3D ONH reconstructions. The lamina cribrosa (LC) microarchitecture was delineated, segmented and sampled on a discrete grid to compute the LC connective tissue volume (CTV), LC connective tissue volume fraction (CTVF), the degree of anisotropy, the predominant laminar beam orientation, and the number of beams through the thickness of the LC within each sampling volume, which were regionalized into peripheral and central LC regions of equal area. Linear mixed effect statistical models were used to analyze the effects of treatment on the outcome variables.
The number of laminar beams through the thickness of the LC was significantly higher in the EG eyes compared to the normal controls (16%, p<0.001), and this effect was larger in the peripheral laminar region (Figure). CTV was also significantly increased by 17% in the EG eyes (p=0.005), as was LC thickness (28%, p<0.001). Anisotropy was significantly lower in the EG eyes (-9%, p<0.05). CTVF was not significantly different by treatment.
Results suggest that the number of beams through the thickness of the LC increases in early EG. These data, along with changes in LC anisotropy, CTVF, and thickness indicate widespread LC connective tissue remodeling and restructuring early in glaucoma, which likely changes its biomechanical response to IOP.<br /> <br /> 1Yang H, et al. IOVS 2009;50:224-234<br /> 2He L, et al. IOVS 2014;55:574-586<br /> 3Yang H, et al. IOVS 2011;52:345-363
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