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Naoki Kiyota, Yukihiro shiga, Kohei Ichinohasama, Shiori Suzuki, Minami Yoshida, Naoto Honda, Hiroshi Kunikata, Toru Nakazawa; The Impact of Intraocular Pressure Elevation on Optic Nerve Head and Choroidal Blood Flow. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5082. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To assess, with laser speckle flowgraphy (LSFG), blood flow (BF) in the choroid and optic nerve head (ONH) tissue during artificially elevated intraocular pressure (IOP).
This prospective study included 20 right eyes of 20 healthy volunteers (29.9 ± 5.3 years, male: female = 8:12). The testing protocol had four phases: baseline, +10 mmHg IOP, +20 mmHg IOP, and recovery. The +10 and +20 mmHg IOP phases were achieved by pushing against the eyelid with a newly developed tubular device attached to the LSFG apparatus. During each phase, LSFG parameters, blood pressure, pulse rate, and IOP were recorded. The change in each variable against the baseline was calculated as a percentage. We also evaluated changes in pulse waveform parameters, including mean blur rate (MBR) and flow acceleration index (FAI), during the protocol in both the choroid and ONH tissue.
Artificial +10 and +20 mmHg elevations in IOP and recovery to baseline were successfully achieved (P < 0.01, ANOVA). Blood pressure and pulse rate did not change during the protocol (P = 0.64-0.99). During IOP elevation, MBR and FAI were higher in the ONH tissue than the choroid (+10 mmHg: 91.2 vs. 84.6%, 113.8 vs 107.1%; +20 mmHg: 77.0 vs 63.7%, 122.9 vs. 105.0%, respectively; P = 0.04, two-way ANOVA)
The hemodynamic response to IOP elevation differs in the ONH tissue and choroid in healthy subjects. LSFG enables the assessment of ocular BF autoregulation in the ONH tissue.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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