The Tacticon Tacticon- The Tactile Circumferential Discriminator: A new, simple non-invasive screening device to identify diabetic patients at risk of foot ulceration. Quantitatively measured directional sensibility had the highest sensitivity and specificity when calculated for patients who had received a diagnosis of neuropathy from the neurologist. Data suggest that the TCD is a simple and reliable new technique for population screening for neuropathy and foot ulcer risk, and there was a highly significant correlation between the results obtained compared with both filaments and VPT.