Corneal confocal microscopy is increasingly used to assess peripheral neuropathy, but its ability to distinguish painful from painless neuropathy remains uncertain. A cross-sectional analysis from the Maastricht Study evaluated the association of wide-field corneal confocal microscopy (WF-CCM) parameters with electromyography (EMG) abnormalities and neuropathic pain in 3425 participants with and without (pre)diabetes. The analysis was published in the Diabetologia. 
The mean participant age was 59.2 years; 51.6% were women, 15% had prediabetes, and 19% had type 2 diabetes, with a median diabetes duration of 3.0 years. Three automated WF-CCM parameters were analyzed: corneal nerve branch density (CNBD), corneal nerve fiber density (CNFD), and corneal nerve fiber length (CNFL). An axonal degeneration composite score was derived from compound muscle action potential amplitudes of the peroneal and tibial nerves and the sensory nerve action potential amplitude of the sural nerve. EMG amplitudes were categorized as normal or as minor (≤10th percentile), moderate (≤5th percentile), or severe (≤2.5th percentile) abnormalities. Neuropathic pain was defined by a modified DN4 score ≥3.
Regression analyses demonstrated statistically significant associations between EMG-defined axonal degeneration and WF-CCM measures (CNFL β=−0.51 [95% CI −0.78, −0.24]; CNFD β=−1.56 [95% CI −3.04, −0.08]; CNBD β=−3.08 [95% CI −5.51, −0.64]; all p<0.05). However, no significant associations were observed between neuropathic pain and WF-CCM parameters (all p>0.1).
As a cross-sectional study, these findings demonstrate association rather than causation. The results suggest that WF-CCM reflects structural nerve abnormalities but may have limited utility in distinguishing neuropathic pain.