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L. Schmetterer, E. Polska, G. Garhöfer; Evidence for Dilatation of the Central Retinal Artery in Patients With Type 1 Diabetes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5007.
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Conflicting results regarding retinal blood flow in early diabetes have been published. Whether this is related to methodological aspects, patient selection and glycemic control has yet to be clarifed. In the current study, we tested the hypothesis that the diameter of the central retinal artery (CRA) is increased in diabetic subjects.CRA diameter was calculated based on a previously published method (Dorner et al. 2002 Curr Eye Res) based on combined measurements of retinal vessel diameters, retinal blood velocities in branch veins and blood velocities in the central retinal artery.
In the present study 16 patients with insulin dependent diabetes mellitus (IDDM) and no or mild non-proliferative diabetic retinopathy were included. 16 healthy age- and sex-matched subjects served as controls. Retinal blood flow was measured by combining retinal venous diameters data obtained with a Retinal Vessel Analyzer and retinal blood velocity data obtained with bi-directional laser Doppler velocimetry. To gain information on total retinal blood flow all veins entering the optic nerve were measured and the data of the individual vessels were added. Mean flow velocity in the CRA was assessed using color Doppler imaging. Based on these measurements the diameter of the CRA was calculated.
Retinal blood flow amounted to 49.9 ± 11.3 µl/min and 45.1 ± 9.0 µl/min in the diabetic and the healthy control group, respectively (p = 0.19 between groups). Mean flow velocity in the CRA tended to be higher in healthy subjects (6.9 ± 0.7 cm/s) than in diabetic patients (6.5 ± 1.1 cm/s), but this effect was not significant (p = 0.24 between groups). Calculated CRA diameter was significantly increased in diabetic patients as compared to healthy control subjects (179.7 ± 12.7 µm versus 165.5 ± 9.9 µm, p = 0.002 between groups).
The present study indicates that CRA diameters are increased in patients with IDDM and no or mild non-proliferative diabetic retinopathy. This needs to be considered when interpreting color Doppler imaging data in this disease. Thus, in patients with IDDM, reduced blood velocity in the CRA can therefore not necessarily be interpreted as reduced retinal blood flow.
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