Diagnostic value of optic disc retinal nerve fiber layer thickness for diabetic peripheral neuropathy

Objective To investigate the value of optic disc retinal nerve fiber layer (RNFL) thickness in the diagnosis of diabetic peripheral neuropathy (DPN). Methods Ninety patients with type 2 diabetes, including 60 patients without DPN (NDPN group) and 30 patients with DPN (DPN group), and 30 healthy participants (normal group) were enrolled. Optical coherence tomography (OCT) was used to measure the four quadrants and the overall average RNFL thickness of the optic disc. The receiver operator characteristic curve was drawn and the area under the curve (AUC) was calculated to evaluate the diagnostic value of RNFL thickness in the optic disc area for DPN. Results The RNFL thickness of the DPN group was thinner than those of the normal and NDPN groups in the overall average ((101.07 +/- 12.40) mu m vs. (111.07 +/- 6.99) mu m and (109.25 +/- 6.90) mu m), superior quadrant ((123.00 +/- 19.04) mu m vs. (138.93 +/- 14.16) mu m and (134.47 +/- 14.34) mu m), and inferior quadrant ((129.37 +/- 17.50) mu m vs. (143.60 +/- 12.22) mu m and (144.48 +/- 14.10) mu m), and the differences were statistically significant. The diagnostic efficiencies of the overall average, superior quadrant, and inferior quadrant RNFL thicknesses, and a combined index of superior and inferior quadrant RNFL thicknesses were similar, and the AUCs were 0.739 (95% confidence interval (CI) 0.635-0.826), 0.683 (95% CI 0.576-0.778), 0.755 (95% CI 0.652-0.840), and 0.773 (95% CI 0.672-0.854), respectively. The diagnostic sensitivity of RNFL thickness in the superior quadrant reached 93.33%. Conclusions The thickness of the RNFL in the optic disc can be used as a diagnostic method for DPN.