Comparison of Precision, Agreement, and Accuracy of Two Swept-Source Optical Coherence Tomography Biometers

Background/Objectives: This study's aim was to compare the precision, agreement, and accuracy in axial length (AL) measurements of Argos^® (Alcon Healthcare, US) and Eyestar 900^® (Haag-Streit, Switzerland) swept-source optical coherence tomography (SS-OCT) biometers. Methods: We performed a prospective evaluation of two diagnostic devices. Three consecutive measurements of AL with the Argos^® and the Eyestar^® 900 SS-OCT biometers were conducted in random order in eyes undergoing cataract surgery in Barcelona, Spain. The main endpoint was the median difference in AL between devices. Secondary endpoints included agreement on Bland-Altman plots and 95% limits of agreement (LoAs), repeatability as measured within-subject standard deviation (S_W), percent of failed AL measurements, percent of eyes within ±0.50 D and ±1.00 D one month after surgery, and median and mean prediction error. Results: We included 107 eyes of 107 patients (60.8% females, mean age of 73.1 years). The median difference in AL (Argos^®-Eyestar 900^®) was -0.01 mm (interquartile range [IQR], 0.06), p = 0.01. The 95% LoAs were -0.11 to +0.08 mm, with a trend towards less extreme measurements with Argos^® for very short and long eyes. The median (IQR) Sw was 0.0058 (0.0058) and 0.0000 (0.0058) for Argos^® and Eyestar 900^®, respectively. There were no failed AL measurements with either device (0%, 95% CI = 0% to 3.4%). Overall, 96.1% of eyes were within ±0.50 D and 100% were within ±1.00 D. Conclusions: Argos^® and Eyestar 900^® provided statistically different but clinically negligible differences in AL. However, they are not interchangeable in very long or short eyes, due to the different principles used to determine AL.