Confocal microscopy of corneal sub-basal nerve plexus: a quantitative and qualitative analysis in healthy and pathologic eyes.

PURPOSE: To validate corneal sub-basal nerve plexus examination by in vivo corneal confocal microscopy. METHODS: Five parameters of corneal sub-basal nerve plexus in 250 human eyes (nerve fi ber length, number of fi bers, number of beadings, branching pattern, fi ber tortuosity) acquired using in vivo corneal confocal microscopy (Confoscan 4.0; NIDEK Co Ltd) were analyzed. The fi rst operator repeated the parameter analysis twice, performing the 2 evaluations 4 weeks apart. The second operator analyzed the cases once. RESULTS: Intraoperator reproducibility of nerve fi ber length, number of fi bers, and number of beadings (intraclass correlation coeffi cient [ICC] = 0.96, 0.96, and 0.93, respectively) and interoperator reproducibility (ICC = 0.94, 0.95, and 0.87, respectively) were very good. Intraoperator reproducibility for branching pattern was good (ICC = 0.74), whereas interoperator reproducibility was very good (ICC = 0.81). Reproducibility of fi ber tortuosity was good both at intra- and interoperator levels (ICC = 0.69 and 0.60, respectively). CONCLUSIONS: Corneal confocal microscopy with the NIDEK Confoscan 4.0 represents an in vivo, noninvasive, and reproducible diagnostic technique for the analysis of sub-basal corneal nerve plexus. Methods used to analyze quantitative and qualitative variables were highly reproducible. [J Refract Surg. 2009;25:S125-S130.]