Corneal Confocal Microscopy to Diagnose Peripheral Neuropathy: A Systematic Review and Meta-Analysis.

Background and objectivesPeripheral neuropathy (PN) may be diagnosed late or may remain undiagnosed. Studies have shown that measurement of corneal nerve fiber length (CNFL) using corneal confocal microscopy (CCM) may have diagnostic utility in diabetic and other peripheral neuropathies.MethodsThe main databases [CENTRAL, Embase (Ovid), and PubMed] were searched for peer-reviewed literature. Gray literature searching was undertaken using the ProQuest Dissertations & Theses database. The updated Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were used by two authors independently for screening and data extraction. The primary outcome of CNFL was represented by the standardized mean difference and 95% confidence interval, and differences between healthy controls (HC), patients with sub-clinical (PN-), and clinical (PN+) peripheral neuropathy were assessed. Sensitivity analysis was performed to assess the risk of bias.ResultsWe identified n = 52 eligible studies (n = 2995 participants) reporting CNFL across 34 different conditions associated with PN. CNFL was significantly lower in PN+ patients compared to HC (standardized mean difference -1.12, 95% confidence interval -1.32 to -0.33, p ConclusionsThis systematic review and meta-analysis shows that CNFL has utility in the diagnosis of peripheral neuropathies.