Corneal Confocal Microscopy – A Novel, Noninvasive Method to Assess Diabetic Peripheral Neuropathy

Background and aims. This article aims to compare corneal confocal microscopy (CCM) with acknowledged tests of diabetic peripheral neuropathy (DPN), to assess corneal nerve morphology using CCM in diabetic patients, and to underline possible correlations between clinical and biological parameters, diabetes duration and DPN severity. Material and methods. A total of 90 patients with type 2 diabetes were included in the study for whom we measured anthropometric parameters and we performed laboratory measurements (tests). The patients were assessed for diabetic peripheral neuropathy using Semmes-Weinstein Monofilament Testing (SWMT), Rapid-Current Perception Threshold (R-CPT) measurements using the Neurometer®, and CCM. We stratified the patients according to DPN severity, based on four parameters extracted after image analysis. Results. A higher percentage of patients were diagnosed with DPN using CCM (88.8%), compared with SWMT and R-CPT measurement (17.8% and 40% respectively). The incidence of DPN detected with CCM was considerable in patients with normal protective sensation and with normal R-CPT values. Conclusions. Our study showed that corneal confocal microscopy is a useful noninvasive method for diabetic neuropathy assessement in early stages. It was proven to directly quantify small fiber pathology, and to stratify neuropathic severity, and therefore can be used as a new, reliable tool in the diagnosis, clinical evaluation, and follow-up of peripheral diabetic neuropathy.