April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
Vascular Reactivity Reserve and Resting Tonus in Retinal Arterioles of Healthy Subjects
J. K. Adleman; S. Dorner; J. A. Fisher; T. Wong; G. E. Trope; C. Hudson
Author Affiliations & Notes
  • J. K. Adleman
    Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
    Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, Toronto, Ontario, Canada
  • S. Dorner
    Department of Anaesthesiology, University Health Network, Toronto, Ontario, Canada
  • J. A. Fisher
    Department of Anaesthesiology, University Health Network, Toronto, Ontario, Canada
  • T. Wong
    Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, Toronto, Ontario, Canada
  • G. E. Trope
    Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, Toronto, Ontario, Canada
  • C. Hudson
    Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, Toronto, Ontario, Canada
    School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
  • Footnotes
    Commercial Relationships  J.K. Adleman, None; S. Dorner, Thornhill Research Inc., E; J.A. Fisher, RespiractTM TRI, Toronto, Canada, P; T. Wong, None; G.E. Trope, None; C. Hudson, RespiractTM TRI, Toronto, Canada, P.
  • Footnotes
    Support  Vision Science Research Program, Canadian Institutes of Health Research, University of Toronto
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 402. doi:
  • Views
  • Share
  • Tools
    • Alerts
      User Alerts
      You are adding an alert for:
      Vascular Reactivity Reserve and Resting Tonus in Retinal Arterioles of Healthy Subjects
      You will receive an email whenever this article is corrected, updated, or cited in the literature. You can manage this and all other alerts in My Account
      The alert will be sent to:
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation
      Citation

      J. K. Adleman, S. Dorner, J. A. Fisher, T. Wong, G. E. Trope, C. Hudson; Vascular Reactivity Reserve and Resting Tonus in Retinal Arterioles of Healthy Subjects. Invest. Ophthalmol. Vis. Sci. 2009;50(13):402.

      Download citation file:

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

      ×
    • Get Permissions
  • Supplements
Abstract

Purpose: : To determine the magnitude of retinal arteriolar vascular reactivity reserve in relation to the resting tonus of healthy subjects.

Methods: : The retinal arteriolar vascular reactivity was assessed in either eye of five healthy subjects (mean 28, range: 23-32 years). All subjects had a visual acuity of 20/20 or better, no history of ocular disease or refractive surgery and were non-smokers. Vascular reactivity was defined as change from baseline in arteriolar diameter, blood velocity, max:min velocity ratio, and blood flow as assessed by the Canon Laser Blood Flowmeter. Baseline conditions were measured at an end-tidal PCO2 (PETCO2) of 38mmHg and end-tidal PO2 (PETO2) of 100mmHg to determine resting tonus.Two graded vasodilatory stimuli were applied in the form of hypoxic hypercapnia (PETO2 = 83 / PETCO2 = 46 mmHg; and PETO2 = 65 / PETCO2 = 46 mmHg) and a single maximal constrictor stimulus was applied in the form of hyperoxic hypocapnia (PETO2 = 300mmHg / PETCO2 = 30mmHg) in randomized order. A 15 minute interval was employed following hyperoxic hypercapnia to avoid any persistent effects of inhaled oxygen. End-tidal gases were actuated by providing predetermined gas flows of specific PCO2 and PO2 to a sequential gas delivery breathing circuit via an automated gas blender (RespiractTM TRI, Toronto, Canada). Following a 3 minute stabilization period at the beginning of each phase, 3 hemodynamic measurements were acquired in the superior temporal arteriole at approximately 1 disc diameter from the optic nerve head.

Results: : Flow was unchanged during the first and second phase of the dilatory stimuli (+10.0%, SD = 7.9, p=0.558, and +7.7%, SD = 8.5, p=0.693, respectively). Flow was reduced by -32.9% (SD = 0.6, p=0.007) during the constrictor stimulus. There was a non-significant trend for the max:min velocity ratio to increase during the constrictor stimulus and to decrease during the dilatory stimuli.

Conclusions: : Relative to the resting tonus position, the retinal arterioles demonstrated a greater capacity for vasoconstriction than vasodilation in response to the gas stimuli used in this study.

Keywords: retina • hypoxia • laser 
© 2009, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2025 Association for Research in Vision and Ophthalmology.
×
×

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.

×
This site uses cookies. By continuing to use our website, you are agreeing to our privacy policy.Accept