Diabetes Visual Electrophysiological Changes In Clinical Studies

Diabetic Retinopathy can be described as microangiopathy caused by the injury of microvessel. When retina is exposed to hyperglycemia for a long period, endothelium has dysfunction. For many years, efforts of the diabetic retinopathy diagnosis, treatment, and research have been put on blood vessel lesion. However, little attention has been paid to the change of visual function in diabetes. In the experiments, pattern electroretinogram (PERG) and flash electroretinogram (FERG) were used to record normal and streptozotocin-induced abnormal PERG-q wave latency and FERG-b wave latency of Diabetic Rats within 8 weeks, respectively. This allows an early examination of the change in the retina function. The Pattern visual evoked potential (PVEP) and Pattern electroretinogram (PERG) was examined in 10 normal individuals (20 eyes ) and 22 patients ( 37 eyes ) with diabetes mellitus ( DM ), including 8 eyes with DM but no diabetic retinopathy (NDR), 21 eyes with background DR ( BDR) and 8 eyes with proliferative DR ( PDR) . The purpose of this study was to examine diabetic retinopathy, in an effort to deepen the understanding and to provide the experimental evidence for improved treatment.The results show that in comparison with normal rats, on the 3^rd day of the existence of Diabetic Rat model, the diabetic rats starts to havelonger (extended) latency of PERG-q markedly, and since the 1st week, it also has longer latency of PERG-b. In addition, the change occurs earlier in PERG-q than in the FERG-b. The results show that there were significant differences between the normal control group and the DM group in PVEP. The latency of P₁₀₀ was significantly delayed and its amplitude was significantly reduced in the DM group ( P<0.001); There were significant differences between the normal control group and the DM group, the PDR group and the other group in PERG The latency of FERG q-wave was significantly delayed and its amplitude was significantly reduced in the DM group ( P<0.001) .Based on the experimental results given above, we draw the conclusions that diabetes have nerve dysfunctions early before the visual identification of fundus oculi of retinopathy. PERG and PVEP can be used as effective tools to detect the damage of retina in the early stage of DR. It seems that retina of rats in its early developing stage is able to detect the abnormal visual function via electroretinography before the visual identification of retinopathy. The GCL is the first retinal tissue damaged by diabetes, and then the retina function prior to GCL is subsequently impaired.