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I.M. Lanzl, W. Vilser, M. Klopfer, K.E. Kotliar; Temporal Retinal Artery Reaction in Response to Different Colors in Chromatic Flickering Light . Invest. Ophthalmol. Vis. Sci. 2003;44(13):342.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Exposing the retina to flickering light demands maximal delivery of metabolic substrates. In animal studies and in humans different dilatory retinal vessel reactions to this demand were observed. A standardization of the properties of flickering light so far has not been undertaken in different laboratories. Flickering light can be applied using different wavelengths. The temporal vessel response to green-blue and green-red flickering light was examined in our study. Methods: In 15 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, which was integrated into the observing camera light path, switching 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 12 Hz was applied for 10 and 30 seconds. Measurements continued for 2 minutes and were repeated 5 times. Results: With both tested chromatic flickering lights a prompt vessel dilation of retinal arteries in comparison to baseline could be determined in all volunteers. For the group this amounted to 2.4%±1.4% after 9.1±3.3 sec with red-green flicker and 2.0%±0.7% after 10.6±5.3 sec with blue-green flicker when flickering for 10 sec and to 3.2%±1.5% after 26.9±12.6 sec with red-green flicker and 2.6%±1.3% after 20.7±8.0 sec with blue-green flicker when flickering for 30 sec. All dilatory responses were significantly different to baseline values (p<0.01). For all experimental set-ups a reactive constriction could be observed after cessation of the flicker. Conclusions: Flickering light of 12 Hz leads to a prompt and reproducible vessel dilation of retinal arteries. The magnitude of dilation increases with 30 seconds of stimulation compared to 10 sec. We could not demonstrate a significant difference in vessel reaction between the two color flicker set-ups applied here. This could be due to the fact that the chosen flicker set up, switching between two colors and not inducing a major change in the rather high luminance level (~100 lux) stimulates all receptors in healthy persons. In persons suffering from diseases affecting the retina and /or the optic nerve a difference in vessel reaction to different color stimuli might be possible. However flickering light as applied in our experimental set-up represents a fast, reproducible, non invasive stimulus for the examination of potential dilatory properties of retinal arteries.
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