Background/aims: To investigate retinal nerve fiber 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) centering: centered each time (CET) vs. centered once (CO), in terms of RNFL thickness measurement variability on SD-OCT.
Methods: Twenty-seven eyes (14 healthy subjects) had 3 circumpapillary scans with TD-OCT and 3 raster scans (three-dimensional or 3D image data) around ONH with SD-OCT. SD-OCT images were analyzed in two ways: 1) CET: ONH center was defined on each image separately, and 2) CO: ONH center was defined on one image and exported to other images after scan registration. After defining the ONH center, a 3.4mm diameter virtual circular OCT was re-sampled 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 in this healthy cohort. The choice of ONH centering methods did not affect RNFL measurement reproducibility.