Search

Aims/Introduction Diabetic polyneuropathy (DPN) develops in the early stage of diabetes. However, no common diagnostic protocol has yet been established. Here, to verify that the flicker electroretinogram using a hand‐held device can detect the early dysfunction of the peripheral nervous system in patients with diabetes, we investigated the correlation between the progression of DPN and neuroretinal dysfunction. Materials and Methods In total, 184 participants with type 1 or 2 diabetes underwent a flicker electroretinogram (ERG) using a hand‐held device RETeval™ and nerve conduction study. Participants were also evaluated for intima‐media thickness, ankle‐brachial index, toe brachial index and brachial‐ankle pulse wave velocity. Parameters of the nerve conduction study were used to diagnose the severity according to Baba’s classification. A multiple regression analysis was used to examine the associations of ERG parameters with the severity of DPN categorized by Baba’s classification. Diagnostic properties of the device in DPN were evaluated using a receiver operating characteristic curve. Results A multiple regression model to predict the severity of DPN was generated using ERG. In the model, moderate‐to‐severe DPN was effectively diagnosed (area under the receiver operating characteristic curve 0.692, sensitivity 56.5%, specificity 78.3%, positive predictive value 70.6%, negative predictive value 66.1%, positive likelihood ratio 2.60, negative likelihood ratio 0.56). In the patients without diabetic retinopathy, the implicit time and amplitude in ERG significantly correlated with the parameters of the nerve conduction study, brachial‐ankle pulse wave velocity and intima‐media thickness. Conclusions Electroretinogram parameters obtained by the hand‐held device successfully predict the severity of DPN. The device might be useful to evaluate DPN., The progression of diabetic retinopathy and the dysfunction of neuroretina evaluated using the mydriasis‐free flicker electroretinogram showed a significant correlation. In patients without apparent diabetic retinopathy, the electroretinogram data correlated with parameters indicating vascular dysfunction, and with parameters indicating diabetic polyneuropathy, such as data of a nerve conduction study. Therefore, the electroretinogram data might reflect the neural and vascular impairments of the retina in patients with diabetes. The electroretinogram data were able to be used to predict the severity of diabetic polyneuropathy.

Aims/Introduction Diabetic polyneuropathy (DPN) and diabetic retinopathy (DR) are traditionally regarded as microvascular complications. However, these complications may share similar neurodegenerative pathologies. Here we evaluate the correlations in the severity of DPN and changes in the thickness of neuroretinal layers to elucidate whether these complications exist at similar stages of progression. Materials and Methods A total of 43 patients with type 2 diabetes underwent a nerve conduction study (NCS), a macular optical coherence tomography, and a carotid artery ultrasound scan. Diabetic polyneuropathy was classified according to Baba’s classification using NCS. The retina was automatically segmented into four layers; ganglion cell complex (GCC), inner nuclear layer/outer plexiform layer (INL/OPL), outer nuclear layer/photoreceptor inner and outer segments, and retinal pigment epithelium (RPE). The thickness of each retinal layer was separately analyzed for the fovea and the parafovea. Results Fourteen patients were classified as having moderate to severe diabetic polyneuropathy. The thicknesses of the foveal and parafoveal INL/OPL increased in patients with diabetic polyneuropathy compared with patients without. The thickness of the parafoveal retinal pigment epithelium decreased in patients with diabetic polyneuropathy. The thinning of parafoveal ganglion cell complex and foveal and parafoveal retinal pigment epithelium were positively correlated with deterioration of nerve functions in the nerve conduction study, but the thickening of INL/OPL was positively correlated with the nerve function deterioration. The thinning of parafoveal ganglion cell complex and foveal retinal pigment epithelium were positively correlated with the thickening of the carotid intima‐media. Conclusions Depending on the progression of diabetic polyneuropathy, the ganglion cell complex and retinal pigment epithelium became thinner and the INL/OPL became thicker. These retinal changes might be noteworthy for pathological investigations and for the assessment of diabetic polyneuropathy and diabetic retinopathy., (1) The thickness of the foveal and parafoveal inner nuclear layer/outer plexiform layer increased in patients with clinical diabetic polyneuropathy compared with patients without clinical diabetic polyneuropathy. (2) A decrease in the thickness of the parafoveal ganglion cell complex correlated with deterioration of nerve functions in the nerve conduction study. (3) A decrease in the thickness of the parafoveal ganglion cell complex was positively correlated with an increase in the parameters of atherosclerosis and cardiovascular risk factors.