Intra-examiner repeatability and agreement of corneal pachymetry map measurement by time-domain and Fourier-domain optical coherence tomography.

BACKGROUND

To assess the intra-examiner repeatability and agreement of corneal pachymetry maps measured by time-domain (Visante OCT) and Fourier-domain optical coherence tomography (RTVue OCT).

METHODS

This observational cross-sectional study enrolled 72 eyes from 72 volunteers. Only one eye of each patient was chosen randomly to receive repeated scanning with both devices by the same examiner, in order to test the intra-observer repeatability. The first scan by each device from all enrolled eyes was used to analyze the difference and agreement between the two devices. The agreement between the two devices was analyzed by the Bland-Altman method. Intra-observer repeatability of each OCT device was analyzed by intra-class correlation (ICC).

RESULTS

The mean corneal thickness of the central 2 mm zone was 524.3 ± 35.7 µm and 525.4 ± 35.3 µm by the Visante OCT and the RTVue OCT respectively (p = 0.089). The intra-observer repeatability of the RTVue OCT (ICC = 0.994) was superior to that of the Visante OCT (ICC = 0.989) in the central 2 mm zone. However, the intra-observer repeatability of the RTVue OCT in the pericentral 2 to 5 mm zone was not superior to that of the Visante OCT. Both OCT devices had similar repeatability in the pericentral 2 to 5 mm zone [ICC of the Visante OCT = 0.991; 95% confidence interval (CI) 0.986-0.995), ICC of the RTVue OCT = 0.991; 95% CI 0.985-0.994)).

CONCLUSIONS

The difference in CCT measurement by the Visante OCT and the RTVue OCT is probably too small to influence clinical decision making for refractive surgery and glaucoma management. The RTVue OCT demonstrated better intra-observer repeatability in the central 2 mm zone, which probably was related to its rapid image acquisition capability.