Background/aims: To investigate retinal nerve fibre layer (RNFL) thickness measurement reproducibility using conventional time-domain optical coherence tomography (TD-OCT) and spectral-domain OCT (SD-OCT), and to evaluate two methods defining the optic nerve head (ONH) centring: Centred Each Time (CET) vs Centred Once (CO), in terms of RNFL thickness measurement variability on SD-OCT.
Methods: Twenty-seven eyes (14 healthy subjects) had three circumpapillary scans with TD-OCT and three raster scans (three-dimensional or 3D image data) around ONH with SD-OCT. SD-OCT images were analysed in two ways: (1) CET: ONH centre was defined on each image separately and (2) CO: ONH centre was defined on one image and exported to other images after scan registration. After defining the ONH centre, a 3.4 mm diameter virtual circular OCT was resampled on SD-OCT images to mimic the conventional circumpapillary RNFL thickness measurements taken with TD-OCT.
Results: CET and CO showed statistically significantly better reproducibility than TD-OCT except for 11:00 with CET. CET and CO methods showed similar reproducibility.
Conclusions: SD-OCT 3D cube data generally showed better RNFL measurement reproducibility than TD-OCT. The choice of ONH centring methods did not affect RNFL measurement reproducibility.
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Funding National Institutes of Health contracts R01-EY13178-09, R01-EY11289-23 and P30-EY08098-20 (Bethesda, Maryland), The Eye and Ear Foundation (Pittsburgh, Pennsylvania) and unrestricted grants from Research to Prevent Blindness (New York).
Competing interests JGF and JSS receive royalties for intellectual property licensed by Massachusetts Institute of Technology to Carl Zeiss Meditec. JGF is a scientific advisor and has stock options with Optovue. GW received research funding from Carl Zeiss Meditec and Optovue. HI, GW and JSS receive royalties for intellectual property, licensed by University of Pittsburgh to Bioptigen, Inc.
Ethics approval Ethics approval was provided by the institutional review board at the University of Pittsburgh.
Patient consent Obtained.