Evaluation of the effect of elevated intraocular pressure and reduced ocular perfusion pressure on retinal capillary bed filling and total retinal blood flow in rats by OMAG/OCT

Zhongwei Zhi, William Cepurna, Elaine Johnson, Hari Jayaram, John Morrison, Ruikang K. Wang

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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 100. mm. Hg in 10. mm. Hg intervals and returned back to 10. mm. Hg. Results: In animals with mean arterial pressure (MAP) of 102. ±. 4. mm. Hg (n = 10), when IOP was increased from 0 to 100. mm. Hg, the capillary density remained at or above 80% of baseline for the IOP up to 60. mm. Hg [or ocular perfusion pressure (OPP) at 40. mm. Hg]. This was then decreased, achieving 60% of baseline at IOP 70. mm. Hg and OPP of 30. mm. Hg. Total RBF was unaffected by moderate increases in IOP up to 30. mm. Hg, beyond which total RBF decreased linearly, reaching 50% of baseline at IOP 60. mm. Hg and OPP 40. mm. Hg. Both capillary density and total RBF were totally extinguished at 100. mm. Hg, but fully recovered when IOP returned to baseline. By comparison, a separate group of animals with lower MAP (mean = 75. ±. 6. mm. Hg, n = 7) demonstrated comparable decreases in both capillary filling and total RBF at IOPs that were 20. mm. Hg lower than in the initial group. Both were totally extinguished at 80. mm. Hg, 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 40. mm. Hg, despite a linear reduction in total RBF.

Original languageEnglish (US)
Pages (from-to)86-95
Number of pages10
JournalMicrovascular Research
StatePublished - Sep 1 2015



  • Intra-ocular pressure
  • Medical and biological imaging
  • Optical coherence tomography
  • Optical microangiography
  • Retinal blood flow

ASJC Scopus subject areas

  • Biochemistry
  • Cardiology and Cardiovascular Medicine
  • Cell Biology

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