Peripapillary nerve fiber layer thickness measurement reproducibility using optical coherence tomography

OBJECTIVE: To assess reproducibility of quadrantic and clock hour sectors of retinal nerve fiber layer thickness in normal eyes using optical coherence tomography. MATERIALS AND METHODS: Normal eyes of healthy volunteers meeting eligibility criteria were imaged by two inexperienced operators. Six 360° circular scans with a diameter of 3.4 mm centered on the optic disc were obtained during each scanning session, and a baseline image was formed using 3 high-quality images defined by the software. Images were obtained on three different days within a 4-week period. Variance and coefficient of variation (CV) were calculated for quadrantic and retinal nerve fiber layer clock hour sectors obtained from the baseline image. RESULTS: Five normal eyes were scanned. Intraoperator reproducibility was high. The mean (±SD) CV for total retinal nerve fiber layer thickness was 5.3±3.82% and 4.33±3.7% for operators 1 and 2, respectively. Interoperator reproducibility was good with statistically similar variance for all quadrantic and clock hour retinal nerve fiber layer parameters (P=.42 to .99). The nasal retinal nerve fiber layer was the most variable sector for both operators (mean CV: 10.42% and 7.83% for operators 1 and 2, respectively). Differences in mean total, nasal, temporal, and superior retinal nerve fiber layer thickness were not statistically significant between operators for all eyes; however, for inferior retinal nerve fiber layer thickness, there was a significant (P=.0007) difference between operators in one eye. CONCLUSION: Peripapillary retinal nerve fiber layer thickness assessments using optical coherence tomography have good intraoperator and interoperator reproducibility. Inexperienced operators can generate useful measurement data with acceptable levels of variance.