Purchase this article with an account.
E.D. Gilmore, D. Preiss, J. Fisher, C. Hudson; Change in Retinal Arteriolar Diameter, Blood Velocity and Blood Flow during an Isocapnic Hyperoxic Provocation . Invest. Ophthalmol. Vis. Sci. 2003;44(13):357.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To define the magnitude, and rate of change in retinal arteriolar diameter, blood velocity, and blood flow as measured by the Canon Laser Blood Flowmeter (CLBF) in a group of normal subjects during an isocapnic hyperoxic provocation. Methods: Eight normal volunteers (mean age 28 years; SD=6 years; M:F 4:4) breathed via a partial rebreathing isocapnia circuit (Hi-Ox SR, Viasys). Retinal blood flow was measured in either the supero- or infero-temporal arteriole using the CLBF. Seven measurements were acquired while the subject breathed air to establish baseline values for diameter, velocity and flow. An isocapnic hyperoxic stimulus was then instituted and maintained for 20 minutes. Subsequently, air was re-administered for a further 10 minutes whilst maintaining isocapnia at baseline levels. A minimum of 7 consecutive CLBF readings were made at each condition. Retinal blood flow measurements were acquired at least every minute over the course of the study. Results: Group mean arteriolar diameter was 98.7µm (SD=3.9µm; 84-109µm) prior to isocapnic hyperoxic provocation, decreased to 77.3µm (SD=3.0µm) during provocation (p<0.001) and recovered to 98.6µm (SD=3.5µm) on removal of the stimulus. Group mean retinal blood velocity was 33.9mm/sec (SD=7.8mm/sec; 29-40mm/sec) prior to provocation, decreased to 17.9mm/sec (SD=5.3mm/sec) during provocation (p<0.001) and recovered to 29.0mm/sec (SD=6.9mm/sec). Group mean retinal blood flow was 8.1µL/min (SD=2.1µL/min; 4.7-11.4µL/min) prior to provocation, decreased to 3.7µL/min (SD=1.2µL/min) during provocation (p=0.001) and recovered to 6.7µL/min (SD=1.8µL/min). Conclusions: Using this isocapnic hyperoxic stimulus in combination with the CLBF, it proved possible to non-invasively quantify the change in retinal arteriolar diameter, blood velocity and blood flow. This technique will form the basis for a standard test to non-invasively quantify retinal vascular reactivity.
This PDF is available to Subscribers Only