A variety of studies demonstrate that ocular blood flow is altered in diabetes and retinal perfusion abnormalities have been proposed to contribute to the pathogenesis of diabetic retinopathy. Various animal and human studies have demonstrated that retinal and optic nerve blood flow increase in response to diffuse luminance flicker. Based on studies with ERG, this effect has been attributed to augmented activity in the retinal ganglion cells and associated axons indicating a coupling mechanism between neuronal activity and retinal blood flow. Whereas a variety of studies describe the effects of flickering light on retinal and optic nerve head blood flow, the knowledge about this coupling in the diabetic retina is sparse. In view of the fact that neural activity and blood flow are strongly coupled in the human retina, one could hypothesize that neurodegenerative changes in the retina could contribute to the vascular dysregulation and in turn lead to changes of ocular perfusion. The investigators set out to investigate whether the coupling of neural activity and blood flow is impaired in patients with early stage diabetic retinopathy compared to those in healthy volunteers.
Study Type
OBSERVATIONAL
Enrollment
100
non-invasive haemodynamic measurements of retinal vessel diameters and laser Doppler velocimetry
Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Vienna, Austria
Intraocular pressure
Time frame: 90 minutes
Retinal arterial and venous diameter
Time frame: 90 minutes
Retinal blood velocity
Time frame: 90 minutes
Pattern ERG
Time frame: measured once on the study day
Mean arterial pressure
Time frame: 90 minutes
Blood glucose
Time frame: measured once on the study day
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