June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Retinal Arteriolar Dilation to Flicker Light is Reduced with Repeated Stimulation
Author Affiliations & Notes
  • Jonathan Noonan
    Centre for Eye Research Australia, East Melbourne, VIC, Australia
  • Ryan Man
    Centre for Eye Research Australia, East Melbourne, VIC, Australia
  • Thanh Nguyen
    Centre for Eye Research Australia, East Melbourne, VIC, Australia
  • Jie Jin Wang
    Centre for Eye Research Australia, East Melbourne, VIC, Australia
    Centre for Vision Research, Sydney, NSW, Australia
  • Ecosse Lamoureux
    Centre for Eye Research Australia, East Melbourne, VIC, Australia
    Singapore Eye Research Institute, Singapore, Singapore
  • Footnotes
    Commercial Relationships Jonathan Noonan, None; Ryan Man, None; Thanh Nguyen, None; Jie Jin Wang, None; Ecosse Lamoureux, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 5830. doi:https://doi.org/
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      Jonathan Noonan, Ryan Man, Thanh Nguyen, Jie Jin Wang, Ecosse Lamoureux; Retinal Arteriolar Dilation to Flicker Light is Reduced with Repeated Stimulation. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5830. doi: https://doi.org/.

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

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Abstract

Purpose: Flicker light-induced retinal vasodilation, a marker of dynamic retinal function that is impaired in patients with diabetes or diabetic retinopathy, is reproducible when repeated at one hour but the effect of short-term repeated stimulation is unknown. We investigated the impact of restimulation after five and thirty minutes on the reproducibility of retinal arteriolar and venular dilations.

Methods: The flicker light response was measured in non-smokers without any chronic medical conditions using the Dynamic Vessel Analyzer (DVA, IMEDOS, Germany). A temporal arteriole and venule segment was selected while the fundus was examined under red-free light. Baseline diameters were recorded for 50 seconds, followed by 20 seconds of flickering light and an 80 second recovery period. The 100-second flicker cycle was repeated twice per test. The flicker light response test was repeated after 5 and 30 minutes rest. Maximum vessel dilation was calculated as the average maximum percentage increase in vessel diameter during flicker stimulation compared to that before stimulation. Within-subject differences were assessed using repeated measure analysis of variance.

Results: 19 participants were recruited (74% female; mean ± SD age 33 ± 5.9 years). Mean ± SD maximum arteriole dilations during stimulation were at baseline: 3.27 ± 2.10%; after five minutes: 2.68 ± 1.89%; and after a further thirty minutes: 3.28 ± 2.09%. Maximum arteriolar dilation was significantly reduced when repeated after five minutes (p = 0.048) but not after thirty minutes (p = 0.958) compared to the baseline test. Corresponding mean ± SD maximum venule dilations were 4.56 ± 1.48%, 4.16 ± 1.61% and 4.61 ± 1.66%, respectively, without statistically significant differences (p > 0.05 for all). Arteriole and venule diameters before flicker stimulation were not significantly different between baseline and repeated tests.

Conclusions: Repeated flicker light stimulation within five minutes, but not thirty minutes, appears to reduce retinal arteriolar vasodilations in healthy humans. This temporal effect, probably due to a bleaching of photoreceptors or exhaustion of dilatory molecules, suggests that sufficient recovery time is needed to ensure reliable measurements in repeated measure designs.

Keywords: 550 imaging/image analysis: clinical • 688 retina • 499 diabetic retinopathy  
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