Imaging of the Corneal Subbasal Whorl-like Nerve Plexus: More Accurate Depiction of the Extent of Corneal Nerve Damage in Patients With Diabetes

Purpose: To show that noninvasive in vivo corneal confocal microscopy (IVCM) can make more accurate imaging of the corneal subbasal nerve plexus possible. This diagnostic technique monitors the status of diabetic peripheral neuropathy. However, it is difficult to accurately confirm the corneal area captured by IVCM, which can induce measurement errors. Because the whorl-like characteristic pattern of the corneal subbasal nerve plexus is in the inferocentral cornea, we evaluated whether IVCM images of the whorl-like patterns can accurately evaluate the corneal nerve fibers in diabetic neuropathy. Methods: Forty-seven patients with diabetes (DM group) and 21 healthy control subjects underwent IVCM examination to compare the characteristics of the corneal subbasal nerve plexus around the central cornea (conventional method) and the whorl-like pattern in the inferocentral cornea (study method). We measured the total corneal nerve fiber and branch length (CNFL). Results: The total CNFL were significantly shorter in the DM group than in the control group and tended to decrease with progression of diabetic retinopathy, nephropathy, neuropathy, and decreased corneal sensation. There was a significant positive correlation between the CNFL values obtained with the conventional method and those obtained with the study method. The coefficient of variation of the CNFL values in the study method was significantly smaller than in the conventional method. Conclusions: Our findings indicated that IVCM measurements of the whorl-like patterns may accurately define the extent of corneal nerve damage in order to monitor diabetic peripheral neuropathy.