Inter-Device Agreement of Retinal Nerve Fiber Layer Thickness Measurements using Spectral Domain Cirrus HD OCT

1. Gong Je Seong
2. Samin Hong
3. Chan Yun Kim

Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Republic of Korea

Purpose: To assess the inter-device agreement of peripapillary retinal nerve fiber layer (RNFL) thickness measurements by two spectral domain Cirrus HD optical coherence tomography (OCT) devices in healthy Korean subjects.

Methods: Eleven eyes of eleven healthy volunteers were enrolled to this study. Each eye was scanned with the Optic Disc Cube 200 x 200 Scan of two Cirrus HD OCT devices for peripapillary RNFL thickness calculation. The inter-device agreements of two Cirrus HD OCTs for average, quadrant, and clock-hour RNFL thickness values were determined with Wilcoxon signed rank test, Friedman test, Cronbach's alpha (α), intraclass correlation coefficient (ICC), coefficient of variation (COV), and Bland-Altman plot.

Results: Mean age of all participations was 25.82 ± 3.28 years and all they had 0.00 LogMAR of best-corrected visual acuity. The signal strengths of scans from two Cirrus HD OCT were not significantly different (p=0.317). The inter-device agreement of average RNFL thickness was excellent (α=0.940, ICC=0.945, COV=2.45 ± 1.52 %). However, that of nasal quadrant RNFL thickness was not very good (α=0.715, ICC=0.716, COV=5.72±4.64 %). Also, on the Bland-Atman plot, the extent of agreement of two Cirrus HD OCTs for RNFL thickness was variable according to scanned sectors.

Conclusions: The inter-device agreement of two spectral domain Cirrus HD OCT devices for peripapillary RNFL thickness measurements was generally excellent but variable according to scanned area. Thus, the physicians should keep this fact in mind before judging a change of RNFL thicknesses if they were measured by different OCT devices.