Repeatability and Agreement of Swept Source and Spectral Domain Optical Coherence Tomography Evaluations of Thickness Sectors in Normal Eyes

Abstract

PURPOSE OF THE STUDY: The purpose of the study was to evaluate the clinical efficacy of swept-source optical coherence tomography (SS-OCT), we compared the intradevice repeatability of thickness measurements obtained using SS-OCT to that of measurements obtained using spectral domain OCT (SD-OCT), and assessed the interdevice agreement of thickness measurements.

MATERIALS AND METHODS: This cross-sectional prospective study involved 3 consecutive measurements of peripapillary retinal nerve fiber layer (PP-RNFL) and ganglion cell-inner plexiform layer thickness in healthy subjects, using 2 different OCT systems. Intraclass correlation coefficients (ICCs) and coefficients of variability were calculated and compared for repeatability and agreement between study groups. Intradevice ICCs for each OCT system were compared, and Bland-Altman plots were used to evaluate their agreement.

RESULTS: Fifty-eight eyes from 58 healthy subjects (25 men and 33 women) were analyzed. SS-OCT images yielded larger PP-RNFL thickness values than SD-OCT images in every sector examined. In contrast, SD-OCT images yielded larger macular ganglion cell-inner plexiform layer thickness values than SS-OCT images. For SS-OCT, intradevice ICCs were ≥0.9 for all sectors. However, for SD-OCT, the 3 PP-RNFL measurement sectors had correlation coefficients <0.9. Interdevice ICCs varied more and were lower than intradevice values, because thickness measurement values differed between the OCT devices.

CONCLUSIONS: Measurements differed between systems even for the same subject. SS-OCT had an intradevice repeatability similar to that of SD-OCT. These findings support the clinical application of SS-OCT.