Abstract
Abstract: :
Purpose: Flicker stimulation is known to increase retinal arterial and venous diameters in animals and humans, indicating a tight coupling between neural activity and blood flow in the retina. The aim of the present study was to investigate whether the response of retinal vessel diameters is altered in patients with early stage diabetes. Methods: 26 patients with early stage insulin dependent diabetes mellitus with non or mild non-proliferative retinopathy and 26 age and sex matched healthy volunteers were included in the study. Diameters of retinal vessels were recorded continuously with the Zeiss Retinal Vessel Analyzer. During this measurement 3 episodes of flicker stimulation (16, 32 and 64 seconds) were applied at a frequency of 8 Hz. Results: In non diabetic volunteers, flicker stimulation increased retinal arterial diameters by +1.6±1.8% (16 sec, p<0.001), +2.8±2.2% (32 sec, p<0.001), +2.8±1.6% (64 sec; p<0.001). In diabetic patients retinal arterial diameters tended to increase but this effect did not reach level of significance. +0.1± 3.1% (16 sec, p=0.9), +1.1±2.7%(32 sec, p=0.07), +1.0±2.8% (64 sec, p=0.1). The flicker response in diabetic subjects was less pronounced than in healthy volunteers (p=0.003). Conclusion: Response to diffuse luminance flicker is significantly diminished in patients with early stage diabetes. Whether this diminished response can be attributed to altered retinal vascular reactivity or to decreased neural activity has yet to be clarified.
Keywords: diabetes • blood supply • ganglion cells