Retinal Neurodegeneration Associated With Peripheral Nerve Conduction and Autonomic Nerve Function in Diabetic Patients

Abstract

In this study, we evaluated the correlation of retinal thickness with peripheral nerve conduction and autonomic nerve function in diabetic patients. Cross-sectional study. Medical records of 160 patients (mean age, 63.61 ± 12.52 years) with diabetes without diabetic retinopathy or mild nonproliferative diabetic retinopathy (NPDR) were reviewed. The mean retinal thickness of the parafoveal area and ganglion cell/inner plexiform layer (GC-IPL) thickness in 6 macular regions were measured using optical coherence tomography. Peripheral nerve conduction studies were conducted on peroneal and posterior tibial motor nerves and the sural sensory nerve. Five cardiovascular autonomic function tests were performed. We classified patients into groups by severity of peripheral neuropathy and autonomic dysfunction and analyzed the correlations with mean retinal thickness. The mean retinal thickness of the parafovea was 315.05 ± 12.70μm and mean macular GC-IPL thickness was 79.89 ± 4.70μm. Macular GC-IPL thickness showed significant correlation with peripheral nerve conduction (no peripheral neuropathy vs definite peripheral neuropathy: 82.0 ± 4.8μm vs 75.2 ± 3.8μm, P < .001). GC-IPL thickness decreased with severity of autonomic nerve dysfunction (no/mild dysfunction vs severe dysfunction: 81.2 ± 6.6μm vs 77.6 ± 5.9μm, P= .005). There was no significant correlation between the retinal thickness of the parafovea and electrodiagnostic tests. The decrease of GC-IPL thickness was positively correlated with both peripheral nerve conduction and autonomic nerve function in diabetic patients who presented with no diabetic retinopathy or mild NPDR.