June 2020
Volume 61, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2020
Early changes in basal cerebral blood flow and GABAergic activity in the visual cortex of glaucoma patients
Author Affiliations & Notes
  • Anna M Chen
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
    Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, United States
  • Ji Won Bang
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
  • Carlos Parra
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
  • Gadi Wollstein
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
  • Joel S Schuman
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
    Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, New York, United States
  • Kevin C Chan
    Department of Ophthalmology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
    Department of Radiology, New York University School of Medicine, NYU Langone Health, New York, New York, United States
  • Footnotes
    Commercial Relationships   Anna Chen, None; Ji Won Bang, None; Carlos Parra, None; Gadi Wollstein, None; Joel Schuman, Zeiss, Inc (P); Kevin Chan, None
  • Footnotes
    Support  This work was supported in part by the National Institutes of Health R01-EY028125 (Bethesda, Maryland); BrightFocus Foundation G2013077. G2016030 and G20190103 (Clarksburg, Maryland); Research to Prevent Blindness/Stavros Niarchos Foundation International Research Collaborators Award (New York, New York); and an Unrestricted Grant from Research to Prevent Blindness to NYU Langone Health Department of Ophthalmology.
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 905. doi:
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      Anna M Chen, Ji Won Bang, Carlos Parra, Gadi Wollstein, Joel S Schuman, Kevin C Chan; Early changes in basal cerebral blood flow and GABAergic activity in the visual cortex of glaucoma patients. Invest. Ophthalmol. Vis. Sci. 2020;61(7):905.

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

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Abstract

Purpose : Recent studies have indicated reduced blood flow in not only the eye but also the brain in patients with late glaucoma (LG). In contrast, patients with early glaucoma (EG) appear to show increased ocular blood flow, but little is known about their corresponding brain changes and their specific pathology. This study utilized non-invasive functional and molecular imaging biomarkers to determine cerebral blood flow (CBF) and neurochemical changes in the visual cortex of EG and LG patients.

Methods : Four EG (age=67.00±5.26 years; 2F), 6 LG (age=65.33±2.75 years; 1F), and 5 healthy controls (age=63.00±3.11 years; 1F) underwent pseudo-continuous arterial spin labeling (pCASL) functional MRI and MEGA-PRESS magnetic resonance spectroscopy (MRS) at rest using a 3-Tesla MRI scanner. Basal CBF was measured from pCASL in the visual and motor cortices (Figure 1a). For MRS, the level of gamma-aminobutyric acid (GABA) in the visual cortex was quantified through the LCModel software (Figure 2a), and normalized over the N-acetyl aspartate and N-acetyl aspartyl glutamic acid complex (NAA+NAAG) to account for systematic fluctuations following LCModel guidelines.

Results : Basal CBF in the white matter (WM) of the visual cortex was significantly higher for EG compared to LG (p=0.021) and controls (p=0.045), whereas basal CBF in the gray matter (GM) of the visual cortex was significantly higher for EG compared to LG (p=0.042) (Figure 1b). No apparent CBF difference was found within the motor cortex across groups (p>0.05). For MRS, normalized GABA levels appeared lower in EG than in controls (p=0.021), while LG had a trending decease compared to controls (p=0.092) (Figure 2b). Within the glaucoma groups, we also found a negative association between basal CBF and normalized GABA levels in both WM (p=0.038) and GM (p=0.039) (Figures 2c-d).

Conclusions : The elevated basal CBF and lower baseline GABA levels in the visual cortex of EG suggest that vascular autoregulation dysfunction and/or neurochemical adaptation may be occurring in the brain’s visual system apart from the eye during the initial phases of glaucoma pathogenesis. Within glaucoma groups, the inverse correlations demonstrated between basal CBF and baseline GABA levels may also offer a quantitative framework for interrogating inhibitory GABAergic activity and hemodynamic reactivity relationships in the glaucomatous brain during disease progression.

This is a 2020 ARVO Annual Meeting abstract.

 

 

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