Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography

Shaohua Pi; Tristan T. Hormel; Xiang Wei; William Cepurna; Acner Camino; Yukun Guo; David Huang; John C. Morrison; Yali Jia

doi:10.1117/1.NPh.6.4.041104

12 July 2019 Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography

Shaohua Pi, Tristan T. Hormel, Xiang Wei, William Cepurna, Acner Camino, Yukun Guo, David Huang, John C. Morrison, Yali Jia

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Neurophotonics, Vol. 6, Issue 4, 041104 (July 2019). https://doi.org/10.1117/1.NPh.6.4.041104

Abstract

Elevated intraocular pressure (IOP) is an important risk factor for glaucoma. However, the role of IOP in glaucoma progression, as well as retinal physiology in general, remains incompletely understood. We demonstrate the use of visible light optical coherence tomography to measure retinal responses to acute IOP elevation in Brown Norway rats. We monitored retinal responses in reflectivity, angiography, blood flow, oxygen saturation (sO₂), and oxygen metabolism over a range of IOP from 10 to 100 mmHg. As IOP was elevated, nerve fiber layer reflectivity was found to decrease. Vascular perfusion in the three retinal capillary plexuses remained steady until IOP exceeded 70 mmHg and arterial flow was noted to reverse periodically at high IOPs. However, a significant drop in total retinal blood flow was observed first at 40 mmHg. As IOP increased, the venous sO₂ demonstrated a gradual decrease despite steady arterial sO₂, which is consistent with increased arterial-venous oxygen extraction across the retinal capillary beds. Calculated total retinal oxygen metabolism was steady, reflecting balanced responses of blood flow and oxygen extraction, until IOP exceeded 40 mmHg, and fell to 0 at 70 and 80 mmHg. Above this, measurements were unattainable. All measurements reverted to baseline when the IOP was returned to 10 mmHg, indicating good recovery following acute pressure challenge. These results demonstrate the ability of this system to monitor retinal oxygen metabolism noninvasively and how it can help us understand retinal responses to elevated IOP.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Shaohua Pi, Tristan T. Hormel, Xiang Wei, William Cepurna, Acner Camino, Yukun Guo, David Huang, John C. Morrison, and Yali Jia "Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography," Neurophotonics 6(4), 041104 (12 July 2019). https://doi.org/10.1117/1.NPh.6.4.041104

Received: 8 March 2019; Accepted: 21 June 2019; Published: 12 July 2019

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