Reproducibility of the Retinal Vascular Response to Flicker Light in Asians

Purpose: Dilation of retinal vessels in response to diffuse luminance flicker may reflect endothelial function. Although this has previously been shown to be reproducible in whites, there have been no similar data in Asians. We assess the reproducibility of repeated measurements of this response in Asians. Material and Methods: Healthy Asians (n=33) with normal vision and no history of glaucoma, age related macular degeneration, cataract, or retinal arterial/venous occlusion participated in this study. Repeated measures from the same subjects were taken 30-60 min apart using the Dynamic Vessel Analyser (DVA, IMEDOS, Jena, Germany). Modification was made to the shape of the light source for Asian participants. Correlations of the first and second measures were assessed using Pearson correlation (R-2), and agreement between the two measures was shown using Bland-Altman plots. Results: After modification to the shape of the light source, almost perfect correlation was found between the 1st and 2nd measurements of baseline arteriolar (R-2=0.95) and venular diameters (R-2=0.98) of arteriolar maximum dilation (R-2=0.85). Substantially high correlation between the 1st and 2nd measurements of venular maximum dilation was found (R-2=0.80). Conclusions: Measurements of the dilation response of retinal vessels to diffuse luminance flicker an Asian sample using the DVA show high reproducibility for repeated measures over a short period of time. Such measurements may allow non-invasive quantification of endothelial function to study its association with systemic and ocular diseases.