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Abstract #48052 Published in IGR 13-4
The Effect of Acute Intraocular Pressure Elevation on the Monkey Optic Nerve Head As Detected by Spectral Domain Optical Coherence Tomography
Strouthidis NG; Fortune B; Yang H; Sigal IA; Burgoyne CFInvestigative Ophthalmology and Visual Science 2011; 52: 9431-9437
PURPOSE: To determine whether acutely elevated IOP alters optic nerve head (ONH) structural parameters characterized in vivo using spectral domain optical coherence tomography (SDOCT). METHODS: Five rhesus macaques were tested under isoflurane anaesthesia. SDOCT images of the ONH of both eyes were acquired 30 minutes after IOP was stabilized to 10 mmHg and after 60 minutes to 45 mmHg. The internal limiting membrane, Bruch's Membrane/retinal pigment epithelium, neural canal opening (NCO) and anterior lamina cribrosa surface (ALCS) were delineated using custom software. Differences in SDOCT structural parameters between the two IOP levels were assessed using generalized estimating equations. In 6 eyes of three animals, images were acquired after 10 minutes and 30 minutes of IOP stabilization to 10 mmHg (control experiment). RESULTS: Acute IOP elevation resulted in a reduction in prelaminar tissue thickness (mean = -47 μm, SD = 25 μm, p = 0.002), rim volume (-0.05 mm3, 0.02 mm3, p = 0.002), rim width (-30 μm, 7 μm, p = 0.002) and in an increase in NCO depth (38 μm, 15 μm, p = 0.002). An increase in ALCS depth was significant relative to peripheral Bruch's membrane (48 μm, 24 μm, p =0.002) but not relative to the NCO. No significant parameter changes were detected in the control eyes. CONCLUSIONS: Surface compliance changes in the normal monkey ONH mostly reflect prelaminar and peripapillary deformation. SDOCT compliance testing will further our understanding of the effects of IOP on the ONH and help improve and validate numerical models of ONH biomechanics.
Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health, Portland, OR, USA.
Classification:
6.9.2.2 Posterior (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.2 Optical coherence tomography)
2.14 Optic disc (Part of: 2 Anatomical structures in glaucoma)
5.2 Primates (Part of: 5 Experimental glaucoma; animal models)
