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J. Grimm, J. Reynaud, H. Yang, J. C. Downs, C. F. Burgoyne; Lamina Cribrosa Beam Thickness and Pore Size in the Nonhuman Primate Optic Nerve Head. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1776.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the overall distributions, and inter- and intra-subject differences in lamina cribrosa beam thickness (BT) and pore size (PS) within the optic nerve heads (ONHs) of four bilaterally normal non-human primates.
Following perfusion fixation at IOPs of 10 mmHg, the ONHs were 3D reconstructed at 1.5 µm voxel resolution [Yang et al. IOVS 50(1):224-234, 2009] and the lamina cribrosa was segmented into connective tissue and non-connective tissue voxels [Roberts et al. IOVS 50(2):681-690, 2009]. For each ONH, local thickness was computed for both the connective tissue (BT) and non-connective tissue (PS) voxels using a published algorithm [Hildebrand et al. J Microscopy, 185:67-75 1996]. Local thickness for a tissue voxel is defined as the radius of largest sphere containing the voxel that is contained completely in that tissue.
Laminar BT ranged from ~2 µm to ~27 µm, with more beams concentrated in the smaller radii. Laminar PS ranged from ~2 µm to ~60 µm, with more pores concentrated in the smaller radii. Mean BT was 7.9 ± 3.68 µm and PS was 25.2 ± 15.2 µm. Median BT and PS were 7.35 and 23.43, respectively. Average intra- and inter-subject differences in BT were 0.3 µm and 0.8 µm, respectively. Average intra- and inter-subject differences in PS were 0.9 µm and 1.5 µm, respectively.
Lamina cribrosa BT and PS distributions are remarkably similar within these 8 eyes, although intra-subject differences were much smaller than inter-subject differences. Laminar pores were approximately three times larger than the laminar beams, which matches the laminar connective tissue volume fraction calculations previously reported for these eyes [Roberts et al, IOVS 2009]. Laminar BT and PS can now be mapped, visualized, and regionalized for further analysis.
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