July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Exploring the Haemodynamic Response Function in the occipital lobe in glaucoma
Author Affiliations & Notes
  • Melissa Emily Wright
    School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
    Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
  • Krishna D Singh
    Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
  • Simon K Rushton
    School of Psychology, Cardiff University, Cardiff, United Kingdom
  • Slawomir Kusmia
    Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
    School of Psychology, Cardiff University, Cardiff, United Kingdom
  • Richard G Wise
    Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
    School of Psychology, Cardiff University, Cardiff, United Kingdom
  • D Samuel Schwarzkopf
    School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
  • Tony Redmond
    School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
  • Footnotes
    Commercial Relationships   Melissa Wright, None; Krishna D Singh, None; Simon K Rushton, None; Slawomir Kusmia, None; Richard G Wise, None; D Samuel Schwarzkopf, None; Tony Redmond, None
  • Footnotes
    Support  Fight for Sight (UK) PhD studentship
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 6110. doi:https://doi.org/
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Melissa Emily Wright, Krishna D Singh, Simon K Rushton, Slawomir Kusmia, Richard G Wise, D Samuel Schwarzkopf, Tony Redmond; Exploring the Haemodynamic Response Function in the occipital lobe in glaucoma. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6110. doi: https://doi.org/.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : A full understanding of the neural correlates of visual field loss in glaucoma requires investigation of functional change in both the retina and visual cortex (e.g. with functional Magnetic Resonance Imaging; fMRI). Given that fMRI measures blood oxygenation level as a surrogate for cortical activity, any difference in haemodynamic response between individuals with and without glaucoma needs to be understood before formally comparing inferred functional activity, especially considering vascular risk factors for glaucoma. In this exploratory study, the Haemodynamic Response Function (HRF) at the occipital lobe was compared between glaucoma patients and age-similar controls with ultra-high field 7T fMRI.

Methods : Seven patients with glaucoma (median [range] age: 70.8 [59.5, 86.3] yrs; median [range] MD: -2.2 [-8.4, -0.5] dB) and 7 healthy age-similar controls (median [range] age: 63.0 [53.1, 72.3] yrs; median [range] MD: +0.2 [-1.4, +1.4] dB) underwent HRF mapping with 7T fMRI. A 1.2mm3 functional scan (repetition time, TR: 2s) was located over the occipital lobe, using the cerebellum as an anatomical landmark. To estimate the HRF response, subjects viewed an 11° radial checkerboard monocularly for 2s, then mean grey luminance for 20s. This was repeated 10 times. A structural scan (1mm3, TR: 2.2s) was also acquired. Repetitions were averaged and a HRF was fitted to the data. Peak amplitude (PA), time-to-peak (TTP), and full-width at half-maximum (FWHM) were extracted and compared between groups.

Results : The figure shows raw blood oxygenation level dependent (BOLD) responses and fitted HRFs (individual and group average), with estimates of PA, TTP and FWHM for glaucoma patients and controls. Despite inter-individual differences in HRF in each group, there is no evidence of a difference in any attributes of the function between patients and controls (Bayes Factor [BF01, 2-sided t-test]: 1.82 [PA], 2.15 [TTP], and 1.60 [FWHM]).

Conclusions : The HRF is unlikely to be a confounder when comparing cortical activity between glaucoma patients with fMRI. This ultra-high field resolution enables greater weighting towards smaller blood vessels found in grey matter than nearby major vasculature, and so can be considered accurate for measuring the HRF in the target tissue.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

A: Individual BOLD responses; B: Fitted HRFs for each subject (thick lines: group average); C: peak amplitude; D: time-to-peak; E: full-width at half-maximum

A: Individual BOLD responses; B: Fitted HRFs for each subject (thick lines: group average); C: peak amplitude; D: time-to-peak; E: full-width at half-maximum

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×