Reliability of confocal corneal microscopy for measurement of dendritic cell density in suspected small fiber neuropathy

Introduction/Aims Dendritic cells (DCs) and their contacts with corneal nerves are described in animal models of nerve damage. Dendritic cell density (DCD) is a potential marker of immune activity in suspected small‐fiber neuropathy (SFN). Here, we aim to evaluate the intra‐ and inter‐rater reliability of DCD measurements in suspected SFN. Methods This retrospective study collected DCD from confocal microscopy images from the corneal sub‐basal epithelium of the eye from 48 patients (mean age 49.6 ± 12.1 y, 61% female). Two examiners, each blinded to the other's examinations and measurements, assessed DCD to evaluate inter‐rater reliability. For intra‐rater reliability, the first examiner performed a second measurement after 14 days. DCs were classified into two cell morphological subtypes: mature and immature. Results Test–retest reliability for total DCD showed excellent agreement, with an intraclass correlation coefficient of 0.96 and inter‐rater reliability intraclass correlation coefficient of 0.77. The immature cell subtype showed excellent intra‐rater reliability but lower inter‐rater reliability. Discussion We found that DCD measurements in the corneal sub‐basal epithelium are sufficiently reliable for consideration in clinical studies of patients with suspected SFN.