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Galen Williams, Ruojin Ren, Hongli Yang, J Crawford Downs, Stuart Gardiner, Claude Burgoyne; Optic nerve head (ONH) connective tissue (CT) deformation within Non-Human Primate (NHP) eyes with moderate to severe (M/S) Experimental Glaucoma (EG). Invest. Ophthalmol. Vis. Sci. 2013;54(15):2270.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize ONH CT deformation within 3D histomorphometric reconstructions of 12 M/S EG NHP eyes relative to 9 previously reported early EG (EEG) eyes.1
Trephinated ONH and peripapillary sclera from both eyes of 12 adult NHPs, (9 - 21 years old) were perfusion fixed at IOP 10 mmHg with one normal, and one M/S EG eye (qualitatively determined by the magnitude of longitudinal change in confocal scanning laser tomography). All eyes were then serial sectioned, 3D reconstructed, 3D delineated and parameterized using our existing techniques1. Significant between eye differences for each parameter, for each M/S EG eye (compared to its contralateral control), exceeded previously reported maximum physiologic inter-eye differences (PIDmax)2 and were compared to the range of EEG eye change.1 For all parameters, inter-eye differences (Treated eye value subtracted from its contralateral control eye value) were compared between EEG and M/S EG eyes using t-tests.
Post-Bruch’s membrane opening (BMO) total prelaminar volume in M/S EG eyes increased from 40 to 578% vs 36 to 188% in the EEG eyes. Laminar posterior deformation ranged from -37 to -437 µm in the M/S EG eyes vs -29 to -184 µm in the EEG eyes. Lamina thickness increased 30 to 113 µm in 3 M/S EG eyes, was unchanged in 6 M/S EG eyes and was thinned 23 to 31 µm in 3 M/S EG eyes compared to increases ranging from 20 to 61 µm in 8 of 9 EEG eyes. Posterior scleral canal opening (PSCO) offset expansion (range, 25 - 33 µm) in M/S EG eyes was less than that in the EEG eyes (range, 30 - 85 µm) with 1 M/S EG eye demonstrating PSCO contraction (64 µm). Between-eye differences of Post-BMO total prelaminar volume are predicted by peak IOP and cumulative IOP difference (p=0.002, p=0.017 respectively).
Global posterior deformation and thickening of the lamina cribrosa increase through NHP M/S EG. However, as previously described in humans and monkeys, the lamina is thinned in the most severely deformed eyes. Taken together, our EEG and M/S EG eye data suggest the lamina thickens in most NHP eyes early in the neuropathy then thins as the neuropathy progresses. The hypothesis that the lamina cribrosa thins first in some eyes is under study using longitudinal SDOCT imaging. References 1. Yang, et al. IOVS. 2011;52:345-363. 2. Yang, et al. IOVS. 2009;50:224-234.
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