Investigative Ophthalmology & Visual Science Cover Image for Volume 65, Issue 7
June 2024
Volume 65, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2024
Assessment of neurovascular coupling (NVC) in nonhuman primate (NHP) experimental glaucoma (EG) using laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA) with flicker stimulation
Author Affiliations & Notes
  • Grant Cull
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Juan Reynaud
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Trinity Holthausen
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Dawn Jennings
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Michaela Dunn
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Stuart Keith Gardiner
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Kazuhiro Kurokawa
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Brad Fortune
    Discoveries in Sight Laboratories, Legacy Devers Eye Institute at Legacy Good Samaritan Medical Center, Portland, Oregon, United States
  • Footnotes
    Commercial Relationships   Grant Cull None; Juan Reynaud None; Trinity Holthausen None; Dawn Jennings None; Michaela Dunn None; Stuart Gardiner Heidelberg Engineering GmbH, Code F (Financial Support); Kazuhiro Kurokawa None; Brad Fortune Heidelberg Engineering GmbH (equipment support), Code F (Financial Support)
  • Footnotes
    Support  NIH R01-EY030590 (BF); Legacy Good Samaritan Foundation.
Investigative Ophthalmology & Visual Science June 2024, Vol.65, 1222. doi:
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      Grant Cull, Juan Reynaud, Trinity Holthausen, Dawn Jennings, Michaela Dunn, Stuart Keith Gardiner, Kazuhiro Kurokawa, Brad Fortune; Assessment of neurovascular coupling (NVC) in nonhuman primate (NHP) experimental glaucoma (EG) using laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA) with flicker stimulation. Invest. Ophthalmol. Vis. Sci. 2024;65(7):1222.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : It is well known that flickering light stimuli can elevate retinal and optic nerve head (ONH) blood flow to meet shifting metabolic demands, thus providing a way to noninvasively probe NVC in the living eye. We developed an approach to test the hypothesis that NVC is altered in an NHP model of EG.

Methods : N=8 adult rhesus monkeys (7F/1M, ages 6-19y) with unilateral EG (6-43% retinal nerve fiber layer thickness loss from pre-EG baseline) were imaged bilaterally under sedation by LSFG (Softcare Co., Ltd.) and OCTA (Spectralis, Heidelberg Engineering GmbH) before, during and after flicker stimulation (8 Hz, broad spectrum “white” light, 3.3 log cd/m2). LSFG scans centered on the ONH were recorded in 10-sec bins continuously for 5 min, starting at baseline (BL) 3.5 min before the onset of a 3-min period of flicker, through 1.5 min after flicker ended (recovery). OCTA scans centered on the ONH (768x768x496 voxels over 15°x15°) were recorded once each at BL, 1.5 min into a 3-min period of flicker, and 1 min after flicker ended (recovery). The LSFG parameter of blood flow (mean blur rate, MBR) was measured for ONH tissue (MBRT) and for major vessels within the ONH (MBRV) in each 10-sec bin (Fig1). The caliber of major retinal arteries and veins was measured in manually segmented OCTA en face images (Fig2). Repeated measures ANOVA was used to compare effects of flicker over time and between EG and fellow control (FC) eyes.

Results : Blood flow in the major vessels was lower in EG than FC at BL, but not in ONH tissue (Fig1). Flicker elicited a robust increase in flow (P<0.0001), which was greater in major vessels of EG eyes (P=0.01). During recovery, flow in EG eyes also decreased more than in FC eyes, both in major vessels (P=0.001) and ONH tissue (P=0.003). Flicker increased the caliber of major retinal arteries and veins as measured by OCTA (both P≤0.0001, Fig2) by nearly 10% in both EG and FC eyes, then recovered close to BL in both groups.

Conclusions : Flicker stimulation elicited a strong NVC response measurable by LSFG for flow and by OCTA for caliber. Changes in flow, but not caliber, during flicker and recovery were larger in EG than in FC eyes. Combining LSFG and OCTA to leverage their complementary strengths is a powerful approach for investigating how NVC is altered in glaucoma.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

 

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