Comparison of Corneal Higher-Order Aberrations Measured with Two Instruments Using Scheimpflug Camera System

PURPOSE: To compare the corneal higher-order aberrations (HOAs) of normal young subjects using Galilei(TM) G4 (Zeimer, Port, Switzerland) and Pentacam(R) (Oculus Inc., Wetzlar, Germany). METHODS: Corneal HOAs were measured using Galilei(TM) G4 and Pentacam(R) in 41 healthy individuals (41 eyes). Intraclass correlation coefficients (ICCs) were obtained to evaluate the repeatability of the 2 devices. Differences in HOAs between the 2 instruments were analyzed with a paired t-test and correlations evaluated. RESULTS: All ICCs measured using Galilei(TM) G4 and Pentacam(R) showed more than moderate repeatability (>0.81) except trefoil, tetrafoil, 4th and 5th HOAs. When comparing the measurements obtained with Galilei(TM) G4 and Pentacam(R), total HOAs, spherical aberration (SA), secondary astigmatism and 5th total HOAs were statistically significantly different between the 2 device (all p < or = 0.001). In addition, Galilei(TM) G4 and Pentacam(R) showed discrepancy among all corneal HOAs items. Although the total corneal HOAs and the SA were significantly correlated, other HOA measurements generally exhibited a low correlation. CONCLUSIONS: Corneal HOAs obtained by the 2 instruments cannot be used interchangeably due to their differences and discrepancy although corneal HOAs measured using Galilei(TM) G4 and Pentacam(R) showed relatively high repeatability.

Comparison of Central Corneal Thickness and Anterior Chamber Depth Measured Using Three Different Devices

PURPOSE: To compare measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) obtained using Galilei(TM), Pentacam(R) (Oculus, Wetzlar, Germany) and Lenstar(R) (Haag-Streit, Koeniz, Switzerland) and analyze the measurement agreements. METHODS: CCT and ACD were measured using Galilei(TM), Pentacam(R) and Lenstar(R) in 47 eyes of 25 healthy subjects. The measurements were compared among the 3 devices. RESULTS: The average CCT measurements using Galilei(TM), Pentacam(R) and Lenstar(R) were 552.6 +/- 29.41 microm, 543.9 +/- 30.50 microm and 537.5 +/- 30.26 microm, respectively. The measurements significantly correlated with each other (r > 0.9, p 0.9, p < 0.001), but were statistically significantly different (p = 0.034). The CCT 95% limits of agreement (LoA) between Galilei(TM) and Pentacam(R), Pentacam(R) and Lenstar(R) and Lenstar(R) and Galilei(TM) were 31.95 microm, 44.76 microm and 46.57 microm, respectively and 95% ACD LoA were 0.46 mm, 0.32 mm and 0.28 mm, respectively. CONCLUSIONS: CCT and ACD measured using the 3 devices were highly correlated with each other but the measurements were statistically different. Therefore, the measurements were not interchangeable and these differences should be considered in clinical use.