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Kevin Ivers, Nripun Sredar, Nimesh Patel, Lakshmi Rajagopalan, Hope Queener, Ronald Harwerth, Jason Porter; In vivo changes to lamina cribrosa pore and optic nerve head geometry in non-human primates with early experimental glaucoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1711.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the time-course of in vivo changes in lamina cribrosa pores, optic nerve head (ONH) geometry, and retinal nerve fiber layer thickness (RNFLT) in a monkey model of glaucoma.
Spectral domain optical coherence tomography (SDOCT) [Spectralis HRA+OCT]radial scans (20° field, 48 B-scans with Enhanced Depth Imaging) and 12° circular scans (to quantify RNFLT) of the ONH were acquired before and every 2 weeks after inducing unilateral experimental glaucoma (EG) in 5 rhesus monkeys. The anterior lamina cribrosa surface (ALCS) and Bruch’s membrane opening were manually marked in SDOCT B-scans to determine ALCS depth (ALCSD). High-resolution adaptive optics scanning laser ophthalmoscope (AOSLO) images of the ALCS were acquired. Mean ALCS pore area and elongation were calculated from AOSLO images following 2D to 3D transformation using a thin plate spline surface fit to marked ALCS points.
In EG eyes: (1) mean IOPs were 11.6 ± 2.4 mmHg at baseline, 34.8 ± 10.1 mmHg at Follow-Up 1 (FU1; first change in pore geometry, ALCSD, or RNFLT from baseline), and 39.6 ± 10.1 mmHg at Follow-Up 2 (FU2; most recent time-point), (2) mean ALCSD increased by 133.7 ± 55.3 μm at FU1 and 222.6 ± 34.5 μm at FU2, while RNFLT reduced only by an average of 0.4 ± 7.1 µm at FU1 and 20.8 ± 15.3 µm at FU2, (3) on average, mean pore area changed by +13.8% from baseline to FU1 and by +0.4% from FU1 to FU2, (4) mean pore elongation changed by -4.6% from baseline to FU1 and by +9.6% from FU1 to FU2. In most EG eyes, pores were larger at FU1 and slightly larger by FU2, whereas pores were more circular by FU1 and more elongated (or elliptical) by FU2. However, there was a reduction in mean area for pores located closer to the ONH center in 3 of 5 EG eyes at FU2. In early EG, increases in ALCSD and mean pore parameters occurred prior to a change in RNFLT in 3 monkeys, an increase in ALCSD occurred before a change in RNFLT and mean pore parameters in 1 monkey, and simultaneous changes in ALCSD, mean pore parameters, and RNFLT occurred in 1 monkey.
A posterior deformation of the ALCS preceded, or was concurrent with, measured axon loss in all early EG eyes. Significant alterations in laminar beams and pores accompanied these early ALCSD changes in most EG eyes.
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