Agreement Between Three Optical Coherence Tomography Devices to Assess the Insertion Distance and Thickness of Horizontal Rectus Muscles

Purpose: To assess the agreement between two different spectral domain (SD-OCT) and one swept source (SS-OCT) optical coherence tomography device to measure the insertion distance and the thickness of the horizontal rectus muscles. Methods: Seventy eyes from 35 healthy patients were studied. Three OCT instruments-Spectralis (Heidelberg Engineering Inc., Heidelberg, Germany), Cirrus 5000 (Carl Zeiss Meditec, Dublin, CA), and Triton (Topcon, Inc., Tokyo, Japan)-were used to measure the limbus insertion distance and the thickness of the lateral rectus and medial rectus muscles. The intraclass correlation coefficient (ICC) was calculated to determine the reproducibility and the agreement between the three methods. Results: Measurement of the limbus insertion distance was possible in 100% of cases with the three OCT devices. The thickness could be measured in 75% or more patients with Spectralis, 74% or more with Cirrus, and 78% or more with Triton. The agreement of the insertion distance measurements between the three devices ranged from an ICC of 0.629 or greater to 0.887; for the muscle thickness, the ICC ranged from 0.495 or greater to 0.854. The best agreement existed between the Spectralis and Topcon devices for insertion distance (ICC = 0.715 to 0.887) and for muscle thickness (ICC = 0.641 to 0.854). The reproducibility of each device was good and was higher for insertion distance (ICC = 0.880) than for muscle thickness (ICC = 0.736). The highest reproducibility values were obtained with Triton. Conclusions: The three OCT devices permitted accurate and reproducible measurements of the limbus insertion distance and the thickness of the horizontal rectus muscles, showing moderate to good agreement between the SS-OCT and the two SD-OCT instruments.