Reproducibility and repeatability of ganglion cell-inner plexiform layer thickness measurements in healthy subjects.

Purpose: To assess the reproducibility and repeatability of macular ganglion cell-inner plexiform layer (GC-IPL) thickness measurements in healthy subjects. Procedures: In this observational study, 60 healthy eyes were subjected to macular GC-IPL thickness measurements by means of Cirrus TM high-definition optical coherence tomography (Cirrus version 6.0; Carl Zeiss Meditec, Dublin, Calif., USA) by two examiners in two sessions. Average, minimum and 6 sectoral GCIPL thicknesses were measured. Inter- and intraobserver reproducibility was tested and analyzed by means of the concordance correlation coefficient (CCC). The repeatability of measurements was assessed by the coefficient of repeatability (CR). Results: Mean age (±SD) was 29.63 (±5.1) years. The CRs for average GC-IPL thickness were 2.1 and 2.2 μm for the first and the second operator, respectively. Inter- and intraobserver CCCs ranged from 0.91 (95% CI: 0.89–0.93) to 0.98 (95% CI: 0.96–0.99) and from 0.92 (95% CI: 0.88–0.94) to 0.98 (95% CI: 0.97–0.99), respectively. Conclusions: GC-IPL thickness measurements in young healthy subjects showed excellent reproducibility and repeatability, especially for average and sectoral GC-IPL thickness measurements.