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C. F. Burgoyne, H. Thompson, M. Roberts, I. A. Sigal, J. Downs, H. Yang; Deformation of the Early Glaucomatous Monkey Optic Nerve Head Connective Tissue Following Acute IOP Elevation Within 3-D Histomorphometric Reconstructions. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2137.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize acute and chronic IOP-induced optic nerve head (ONH) connective tissue deformation in nine monkeys at the onset of unilateral early experimental glaucoma (EEG) using 3-D histomorphometry.
Trephinated ONH and peripapillary sclera from both eyes of nine monkeys perfusion fixed with one normal eye at IOP 10 mm Hg and the other EEG eye at 10 (n=3), 30 (n=3) or 45 mm Hg (n=3) (for 15 minutes or more prior to perfusion) were serial sectioned, 3-D reconstructed, 3-D delineated and quantified using our standard 3D histomorphometric parameters. Overall, and for each monkey, inter-eye (EEG eye minus Normal eye) differences for each parameter were calculated and compared by ANOVA. EPIDmax deformations for each parameter were defined to be those statistically significant differences that exceeded the maximum physiologic inter-eye difference (PID) within six bilaterally normal monkeys of a previous report. To assess for hypercompliance within the EEG 30 and 45 eyes , inter-eye differences within these animals were compared to the magnitude of fixed deformation within the EEG 10/10 animals and the inter-eye differences within a separate group of bilaterally normal 10/30 and 10/45 animals from a separate previous report.
Overall ONH connective tissue hypercompliance within the 6 EEG 30/45 eyes was not significant, however the presence of hypercompliant deformation was suggested within a subset of EEG 30/45 eyes. EEG eye EPIDmax deformations considered without regard for fixation IOP included regionally variable posterior laminar deformation, neural canal expansion, lamina cribrosa thickening and posterior (outward) bowing of the peripapillary sclera. Maximum posterior laminar deformation and scleral canal expansion tended to co-localize to a single quadrant (roughly inferior nasal or superior temporal) in the eyes with the least deformation and tended to include both quadrants in the eyes achieving the greatest deformation.
The clinical phenomenon of "cupping" in monkey EEG includes individual-eye specific, connective tissue damage and deformation. The relationship of this deformation to the underlying lamina cribrosa connective tissue architecture and its influences on the blood supply and cell biology of the adjacent astrocytes, glia and retinal ganglion cell axons are under study.
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