Zhongwei Zhi1, William Cepurna2, Elaine Johnson2, Hari Jayaram2, John Morrison2, Ruikang K Wang3. 1. Department of Bioengineering, University of Washington, Seattle, WA 98195, USA. 2. Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA. 3. Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Department of Ophthalmology, University of Washington, Seattle, WA 98195, USA. Electronic address: wangrk@uw.edu.
Abstract
PURPOSE: To determine if retinal capillary filling is preserved in the face of acutely elevated intraocular pressure (IOP) in anesthetized rats, despite a reduction in total retinal blood flow (RBF), using optical microangiography/optical coherence tomography (OMAG/OCT). METHODS: OMAG provided the capability of depth-resolved imaging of the retinal microvasculature down to the capillary level. Doppler OCT was applied to measure the total RBF using an enface integration approach. The microvascular pattern, capillary density, and total RBF were monitored in vivo as the IOP was increased from 10 to 100mmHg in 10mmHg intervals and returned back to 10mmHg. RESULTS: In animals with mean arterial pressure (MAP) of 102±4mmHg (n=10), when IOP was increased from 0 to 100mmHg, the capillary density remained at or above 80% of baseline for the IOP up to 60mmHg [or ocular perfusion pressure (OPP) at 40mmHg]. This was then decreased, achieving 60% of baseline at IOP 70mmHg and OPP of 30mmHg. Total RBF was unaffected by moderate increases in IOP up to 30mmHg, beyond which total RBF decreased linearly, reaching 50% of baseline at IOP 60mmHg and OPP 40mmHg. Both capillary density and total RBF were totally extinguished at 100mmHg, but fully recovered when IOP returned to baseline. By comparison, a separate group of animals with lower MAP (mean=75±6mmHg, n=7) demonstrated comparable decreases in both capillary filling and total RBF at IOPs that were 20mmHg lower than in the initial group. Both were totally extinguished at 80mmHg, but fully recovered when IOP returned to baseline. Relationships of both parameters to OPP were unchanged. CONCLUSION: Retinal capillary filling and total RBF responses to IOP elevation can be monitored non-invasively by OMAG/OCT and both are influenced by OPP. Retinal capillary filling was relatively preserved down to a perfusion pressure of 40mmHg, despite a linear reduction in total RBF.
PURPOSE: To determine if retinal capillary filling is preserved in the face of acutely elevated intraocular pressure (IOP) in anesthetized rats, despite a reduction in total retinal blood flow (RBF), using optical microangiography/optical coherence tomography (OMAG/OCT). METHODS:OMAG provided the capability of depth-resolved imaging of the retinal microvasculature down to the capillary level. Doppler OCT was applied to measure the total RBF using an enface integration approach. The microvascular pattern, capillary density, and total RBF were monitored in vivo as the IOP was increased from 10 to 100mmHg in 10mmHg intervals and returned back to 10mmHg. RESULTS: In animals with mean arterial pressure (MAP) of 102±4mmHg (n=10), when IOP was increased from 0 to 100mmHg, the capillary density remained at or above 80% of baseline for the IOP up to 60mmHg [or ocular perfusion pressure (OPP) at 40mmHg]. This was then decreased, achieving 60% of baseline at IOP 70mmHg and OPP of 30mmHg. Total RBF was unaffected by moderate increases in IOP up to 30mmHg, beyond which total RBF decreased linearly, reaching 50% of baseline at IOP 60mmHg and OPP 40mmHg. Both capillary density and total RBF were totally extinguished at 100mmHg, but fully recovered when IOP returned to baseline. By comparison, a separate group of animals with lower MAP (mean=75±6mmHg, n=7) demonstrated comparable decreases in both capillary filling and total RBF at IOPs that were 20mmHg lower than in the initial group. Both were totally extinguished at 80mmHg, but fully recovered when IOP returned to baseline. Relationships of both parameters to OPP were unchanged. CONCLUSION: Retinal capillary filling and total RBF responses to IOP elevation can be monitored non-invasively by OMAG/OCT and both are influenced by OPP. Retinal capillary filling was relatively preserved down to a perfusion pressure of 40mmHg, despite a linear reduction in total RBF.
Authors: Michael D Roberts; Ian A Sigal; Yi Liang; Claude F Burgoyne; J Crawford Downs Journal: Invest Ophthalmol Vis Sci Date: 2010-06-10 Impact factor: 4.799
Authors: Yu Xiang George Kong; Nicole van Bergen; Bang V Bui; Vicki Chrysostomou; Algis J Vingrys; Ian A Trounce; Jonathan G Crowston Journal: Neurobiol Aging Date: 2012-01-02 Impact factor: 4.673
Authors: Chandrakumar Balaratnasingam; William H Morgan; Louise Bass; Linda Ye; Charlotte McKnight; Stephen J Cringle; Dao-Yi Yu Journal: Brain Res Date: 2008-09-24 Impact factor: 3.252
Authors: Chandrakumar Balaratnasingam; William H Morgan; Louise Bass; Graeme Matich; Stephen J Cringle; Dao-Yi Yu Journal: Invest Ophthalmol Vis Sci Date: 2007-08 Impact factor: 4.799
Authors: Yali Jia; Eric Wei; Xiaogang Wang; Xinbo Zhang; John C Morrison; Mansi Parikh; Lori H Lombardi; Devin M Gattey; Rebecca L Armour; Beth Edmunds; Martin F Kraus; James G Fujimoto; David Huang Journal: Ophthalmology Date: 2014-03-12 Impact factor: 12.079
Authors: Jingjiang Xu; Yuandong Li; Shaozhen Song; William Cepurna; John Morrison; Ruikang K Wang Journal: Microvasc Res Date: 2018-09-26 Impact factor: 3.514
Authors: Stanislava Fialová; Marco Augustin; Corinna Fischak; Leopold Schmetterer; Stephan Handschuh; Martin Glösmann; Michael Pircher; Christoph K Hitzenberger; Bernhard Baumann Journal: Biomed Opt Express Date: 2016-12-16 Impact factor: 3.732
Authors: Marco Augustin; Stanislava Fialová; Corinna Fischak; Leopold Schmetterer; Christoph K Hitzenberger; Bernhard Baumann Journal: Sci Rep Date: 2017-08-18 Impact factor: 4.379
Authors: John C Morrison; William O Cepurna; Shandiz Tehrani; Tiffany E Choe; Hari Jayaram; Diana C Lozano; Brad Fortune; Elaine C Johnson Journal: Invest Ophthalmol Vis Sci Date: 2016-12-01 Impact factor: 4.799