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Hongli Yang, Ruojin Ren, Galen Williams, Howard Lockwood, J Crawford Downs, Stuart Gardiner, Claude Burgoyne; Optic Nerve Head (ONH) Lamina Cribrosa Insertion Migration and Pialization in Moderate and Severe Non-human Primate (NHP) Experimental Glaucoma (EG). Invest. Ophthalmol. Vis. Sci. 2013;54(15):3160.
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To characterize the morphology of the lamina cribrosa insertion into the neural canal wall in moderate to severe (M/S) EG NHP eyes relative to their contralateral controls. M/S EG eye data were then compared to previously reported early EG (EEG) and bilateral normal eye data.
In 19 NHPs, laser-induced chronic IOP elevations were unilaterally induced until confocal scanning laser ophthalmoscopy demonstrated either the onset (EEG: 9 eyes) or progression of ONH surface change to qualitatively determined moderate to severe levels (M/S EG: 10 eyes). Fellow control eyes and both eyes of 6 bilateral normal NHPs, were classified as normal (N). ONHs from all 25 animals were perfusion fixed, digitally reconstructed and 3D delineated. Anterior Laminar Insertion Position (ALIP), Posterior Laminar Insertion Position (PLIP), Laminar Insertion Length (LIL) were calculated for each ONH. Treatment effects were assessed by generalized estimating equations. Inter-eye differences were pooled into 3 groups (N-N, EEG-N and M/S EG-N) and box-whisker plots generated.
ALIP was significantly posterior in the M/S EG eyes compared with N eyes and EEG eyes (both p<0.01, M/S EG: Mean±SD = -75±38 µm, EEG -32±28 µm, N -20±16 µm). PLIP was significantly posterior in the M/S EG eyes compared with N eyes (p=0.01, M/S EG -29±92 µm, N 40±23 µm) but not significantly different from EEG (-2±24 µm, p=0.34). LIL in M/S EG was not different from N eyes although it was significantly increased in EEG eyes compared to N eyes (p<0.01). Individual animal inter-eye differences (EG - N eye) for ALIP and PLIP were larger in M/S EG than EEG (Fig 2). LIL increased in all 9 EEG eyes (14-47 µm), while it was increased only in 5 M/S EG eyes (4-65 µm) and decreased in 5 M/S EG eyes (15-52 µm) (relative to their respective control eyes).
ALI and PLI both migrate outward as the NHP eye becomes progressively damaged by EG. LIL decreases in a subset of M/S EG eyes are consistent with laminar thinning through the course of EG progression as previously described in human glaucoma. Outward ALI and PLI migration is consistent with physical trauma and/or remodeling of the laminar beams that include retrolaminar septal recruitment (Roberts et al, IOVS, 2009).
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