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T. T. Nguyen, J.-J. Wang, S. Rogers, A. Kreis, A. Grosso, J. Shaw, T. Y. Wong; Retinal Vascular Flicker Response in Patients With Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2007;48(13):170.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies show that retinal arteriolar and venular diameters dilate in response to flickering light stimulation, possibly from a physiological response of the retinal endothelium to neural and chemical activities induced by the flickering. We aim to investigate whether this vessel response to light flickering is altered in patients with diabetic retinopathy.
The study sample comprised 25 patients with type 1 or 2 diabetes seen at a tertiary diabetes clinic. Retinopathy was defined on clinical ophthalmoscopic examination. Of the 25 patients, 10 had early diabetic retinopathy. The Dynamic Retinal Vessel Analyzer (Imedos, Germany) was used to measure the diameters of both retinal vessels before, during and after the stimulation. Retinal arteriolar and venular dilation in response to flickering light was defined using the maximal increase during the stimulation proportional to the baseline diameter. One-way ANOVA was used to compare the difference between groups, and then further adjusted for age, glycemia, presence of hypertension and hypercholesterolemia using ANCOVA
Of the 25 patients, 11 were type 1 diabetes and 14 were type 2 diabetes. The mean age of the groups with and without diabetic retinopathy was 49.7 years and 52.0 years, respectively. The mean duration of diabetes in those with and without retinopathy was 13.9 years and 8.0 years, respectively. The mean arteriole dilation induced by light flickering in diabetic patients with and without retinopathy was 1.4% and 3.2%, respectively, (p=0.17), whereas corresponding mean venular dilation was 1.9% and 3.9%, respectively (p=0.004). After adjusting for age, glycemia, presence of hypertension and hypercholesterolemia, venular dilation in those with and without retinopathy was 2.2% and 3.9%, respectively, (p=0.03).
Findings from this sample of diabetic patients suggest that retinal venular dilation is diminished in response to flickering light stimulation in patients with mild retinopathy. This observation suggests that endothelial function is reduced in patients with early diabetic retinopathy, but further studies with larger sample size is needed to clarify the exact mechanisms of this diminished response.
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