Comparison of Retinal Nerve Fiber Layer Thickness Measured by Spectral-Domain and Time-Domain Optical Coherence Tomography

ABSTRACT

PURPOSE: To compare retinal nerve fiber layer (RNFL) thickness measured by time domain (Stratus) and spectral domain (3D) optical coherence tomography (OCT). METHODS: Sixty-nine normal subjects and 92 glaucoma patients were included in the present study. Peripapillary RNFL thickness was measured with Stratus fast RNFL scan and 3D optic disc cube scan on the same day. The relationship between RNFL thickness measurements of the two OCTs were evaluated using a Pearson's correlation analysis. A Bland-Altman plot was used for the comparison of Stratus-OCT and 3D-OCT. RESULTS: In all subjects, average, superior, and inferior quadrant RNFL thicknesses measured by Stratus-OCT were thicker than those measured by 3D-OCT. In contrast, temporal and nasal quadrant RNFL thicknesses measured by 3D-OCT were thicker than those measured by Stratus-OCT. Although there were absolute value differences in RNFL thicknesses, high correlation was observed between Stratus-OCT and 3D-OCT (average: r = 0.897, temporal quadrant: r = 0.728, superior quadrant: r = 0.811, nasal quadrant: r = 0.678, and inferior quadrant: r = 0.905). Bland-Altman plots showed that Stratus-OCT values were greater than 3D-OCT values with relatively high RNFL thickness and the opposite with low RNFL thickness. CONCLUSIONS: For thicker RNFL, Stratus-OCT measurements tend to be greater than 3D-OCT, while for thinner RNFL, 3D-OCT measurements tend to be greater than Stratus-OCT. This difference must be taken into account if comparing measurements made with a Stratus-OCT to the measurements of a 3D-OCT.