gms | German Medical Science

102. Jahrestagung der DOG

Deutsche Ophthalmologische Gesellschaft e. V.

23. bis 26.09.2004, Berlin

How does retinal arterial vessel diameter dilation change with temporal frequency of chromatic flicker application?

Meeting Abstract

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  • corresponding author I. M. Lanzl - Department of Ophthalmology, Technical University Munich
  • K. E. Kotliar - Department of Ophthalmology, Technical University Munich
  • W. Vilser - Biomedical Engineering, Technical University Ilmenau

Evidenzbasierte Medizin - Anspruch und Wirklichkeit. 102. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft. Berlin, 23.-26.09.2004. Düsseldorf, Köln: German Medical Science; 2004. Doc04dogDO.12.09

The electronic version of this article is the complete one and can be found online at:

Published: September 22, 2004

© 2004 Lanzl et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




The exposition of the retina to flickering light is followed by retinal vessel dilation. A standardization of the properties of flickering light so far has not been undertaken in different laboratories. The vessel response to green-blue and green-red flickering light with different exposure frequency was examined in our study.


In 10 young, healthy volunteers the Retinal Vessel Analyzer (RVA) was applied to asses retinal arterial diameters. A baseline measurement was performed for one minute. Then a flicker light alternating between the colors red (600 - 720 nm) - green (530 - 570 nm) and blue (430 - 520 nm) - green (530 - 570 nm) with a flicker frequency of 2, 6, 12, 16 or 20 Hz was applied for 30 sec. All experiments were repeated 3 times. The experiment using 12 Hz stimulation was repeated after 1 week with the same volunteers.


With both tested chromatic flickering lights a prompt vessel dilation of retinal arteries in comparison to baseline could be determined in all volunteers (p<0.001). On average with red-green flicker this amounted to 2.0%±1.1% after 2 Hz stimulation; to 2.9%±1.1% at 6 Hz; to 3.5%±1.4% at 12 Hz; to 3.1%±1.2% at 16 Hz and to 1.8%±0.9% at 20 Hz. With blue-green flicker we found a dilation of 1.7%±1.1% after 2Hz stimulation, of 2.5%±1.1% at 6 Hz; of 3.4%±1.1% at 12 Hz; of 2.7%±1.2% at 16 Hz and of 1.8%±0.8% at 20 Hz. The repeat experiment using 30 sec stimulation after one week showed no statistical difference to the first series (p>0.2).


Flickering light of 30 sec leads to a prompt and reproducible vessel dilation of retinal arteries. An increase in magnitude of dilation could be noted with increased stimulus frequency from 2 Hz to 12 Hz. The maximal amplitude of dilation decreases if the stimulus frequency increases further from 12 Hz to 20 Hz. We therefore think, that flicker application of 12 Hz flicker stimulus constitutes a feasible basis for examinations of retinal vessel behavior, with good dilation magnitude and low patient inconvenience.