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A. Lecleire-Collet, J.-F. Girmens, M. Paques, R. Sofroni, J. Conrath, J.-A. Sahel, A. Gaudric, P. Massin; Reduced Response of Retinal Vessels to Flicker Light Stimulation in Diabetic Patients Without Retinopathy. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5025.
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In healthy subjects, retinal stimulation with flicker light induces retinal vessel dilatation, via a still partially understood neurovascular mechanism. The aim of the study was to determine if this vasomotive response due to retinal neural cell stimulation is impaired early in diabetes, before the occurrence of diabetic retinopathy.
Twenty-eight patients with diabetes (17 patients with type 1 diabetes, 11 patients with type 2 diabetes) without diabetic retinopathy on fundus examination, and 28 age- and sex-matched healthy volunteers were included. The diameter of retinal arteries and veins was measured using the commercially available Zeiss Retinal Vessel Analyzer (RVA). During the examination, three periods of flicker light stimulation (530-600 nm, 12.5 Hz, 20 seconds) were performed. Flicker light-induced retinal arterial and venous responses were assessed using three different calculation methods (R1, R2, R3).
The arterial response to flicker light was significantly reduced in diabetic patients compared with healthy volunteers (Student Test, p < 10-4, p < 10-5, p < 0.001, for R1, R2, R3, respectively). In healthy volunteers, flicker light stimulation increases arterial diameter of 9.39 % +/- 2.51 % (mean +/- SD), 4.14 % +/- 1.78 %, et 4.91 % +/- 2.40 %, for R1, R2, et R3, respectively, compared with 5.97 % +/- 2.89 %, 1.88 % +/- 1.42 %, et 2.92 % +/- 2.07 %, for diabetic patients. Venous response was also decreased in diabetic patients compared with healthy volunteers (Student test, p < 0.05, p < 0.01, p < 0.05, for R1, R2, R3, respectively). In healthy volunteers, flicker light stimulation increases venous diameter of 5.90 % +/- 2.35 % (mean +/- SD), 4.41 % +/- 2.21 %, et 4.57 % +/- 2.02 %, for R1, R2, et R3, respectively, compared with 4.23 % +/- 1.87 %, 2.58 % +/- 1.86 %, et 3.03 % +/- 1.79 %, for diabetic patients.
Flicker light-induced retinal arterial and venous responses are reduced in diabetic patients without diabetic retinopathy. This decrease of retinal vasomotive response may be due to a early decrease of retinal vascular reactivity and / or retinal neural activity.
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