Abstract
Purpose: :
Conventional time-domain optical coherence tomography (OCT) has been shown to provide reproducible retinal nerve fiber layer (RNFL) measurements. Recently, high-speed, high-resolution Fourier-domain 3d-OCT has been introduced to improve OCT quality. It can provide 6x6 mm high-density scans to provide RNFL thickness measurements. The purpose of this study was to test the reproducibility of 3d-OCT RNFL thickness measurements in healthy volunteers.
Methods: :
18 eyes were included into the study. High-density 6x6 mm 3d-scans were registered by 2 independent examiners. RNFL thickness was calculated for 8 areas corresponding to the ETDRS areas and for two ring areas. The ETDRS grid was centered on the optic disc. Intraclass correlation coefficients (ICC), coefficients of variation (COV), and intra-observer variability were calculated. Inter-observer reproducibility was tested by using Bland-Altman analysis.
Results: :
Intrasession reproducibility was good with a mean ICC for examiner 1 and 2 of 0.86 and 0.89, respectively. The mean COV for examiner 1 and 2 was 5.9% and 5%, respectively (range 2.4% to 9.6%). Highest reproducibility was found for the two ring areas and the superior- and inferior quadrants. Mean differences in RNFL thickness measurements for ring 1 and 2 between examiner 1 and 2 were 5.04 µm (range 0.5 to 10.8 µm) and 3.2 µm (range 0.05 to 7.1 µm), respectively.
Keywords: imaging/image analysis: clinical • optic nerve • nerve fiber layer