Repeatability of Ocular Measurements with a Dual-Scheimpflug Analyzer in Healthy Eyes

Abstract

Purpose. To assess the repeatability of the Galilei dual Scheimpflug analyzer (GDSA) in anterior segment examination. Methods. Fifty-two eyes from 52 healthy volunteers were prospectively and consecutively recruited. Anatomic, axial, refractive, and instantaneous parameters were measured with GDSA to provide a complete characterization of the anterior segment. Repeatability was assessed calculating intraclass correlation coefficient (ICC), and coefficient of variation (COV). Results. Correlation among repeated measurements showed almost perfect reliability (ICC > 0.81) for all parameters except thinnest central corneal thickness (CCT) (0.78), corneal thickness average out (0.79), and posterior axial curvature average out (0.60). Repeatability was excellent (COV < 10%) for all parameters except anterior chamber volume and, superior iridocorneal angle and eccentricities. In these last three parameters, repeatability limits were excessively high compared to the mean. Conclusions. GDSA in healthy young persons had an almost perfect correlation in measuring anatomic, axial, instantaneous, and refractive parameters with greater variability for peripheral terms. Repeatability of anatomical parameters like pachymetry, anterior chamber, or iridocorneal angle and eccentricity were limited. In healthy young persons, the other evaluated parameters had very good repeatability and their limits of agreement showed excellent clinical results for this device.

Comparison of Anterior Segment Measurements Obtained by Three Different Devices in Healthy Eyes

“…Our ICC measurements reached nearly perfect reliability, which was in accordance with previous studies on the Galilei [25, 26, 28–31] and the IOL Master [19, 32–34]. Sheppard and Davies [5] reported a mean intrasession repeatability of WAM 5500 of 0.09 D for the spherical component, 0.14 D for the cylindrical component, and 0.07 D and 0.06 D for the J0 and J45; we did not find any other reports regarding the repeatability of the WAM 5500 method.…”

“…Accurate and predictable biometric measurements are required to guarantee the success of various surgeries [ 19 , 20 ]. Previous studies have measured the anterior segment in normal subjects and in subjects with ocular disease using the IOL Master, Galilei, and WAM 5500 [ 3 , 5 , 8 , 21 – 28 ].…”

Does Dry Eye Affect Repeatability of Corneal Topography Measurements?

“… 1 Recent studies have proved that Sirius and similar corneal topography systems are repeatable for healthy subjects. 1 , 2 , 3 , 4 , 5 …”