These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Retinal venous oxygen saturation increases by flicker light stimulation.
    Author: Hammer M, Vilser W, Riemer T, Liemt F, Jentsch S, Dawczynski J, Schweitzer D.
    Journal: Invest Ophthalmol Vis Sci; 2011 Jan 05; 52(1):274-7. PubMed ID: 20671271.
    Abstract:
    PURPOSE: Luminance flicker stimulation of the photoreceptors is known to increase retinal blood flow. Elevated blood velocity was determined using laser Doppler velocimetry, and increased vascular diameters during flicker were observed by measurements with a retinal vessel analyzer. Oxygen supply may be the target of the regulation of retinal blood flow. Thus, the oxygen saturation (SO(2)) in retinal arterioles and venules was investigated along with their diameters. METHODS: Dual-wavelength (548 nm and 610 nm) fundus images were taken in 19 healthy volunteers (mean age, 26 ± 2.5 years) before (baseline) and during luminance flicker stimulation (12.5 Hz; modulation depth, 1:25). Retinal vessel SO(2) (dual-wavelength optical oximetry) and diameters (central retinal arterial and venous equivalents [CRAE and CRVE]) were determined. RESULTS: CRAEs and CRVEs of 193 ± 20 μm and 228 ± 20 μm at baseline increased statistically significant to a maximum of 202 ± 19 μm (P < 0.0005) and 242 ± 17 μm (P < 0.0005), respectively, under flicker stimulation. Although the arterial SO(2) remained unchanged at 98%-99%, an increase of the venous saturation from 60% ± 5.7% to 64% ± 5.9% (P < 0.0005) was found. CONCLUSIONS: In agreement with earlier investigations, the vessel dilation found here indicates an elevation of retinal blood flow by luminance flicker stimulation. This increase of the flow should meet the enhanced metabolic need of the neural retina under a physiological stimulus. The augmentation of venous oxygenation may indicate a higher capillary oxygen concentration, necessary to provide a sufficient diffusion rate of oxygen from the capillaries to the inner retinal tissue.
    [Abstract] [Full Text] [Related] [New Search]