Comparison between the CASIA SS-1000 and Pentacam in measuring corneal curvatures and corneal thickness maps.

PURPOSE: To compare the intra-device repeatability and inter-device reproducibility between two anterior segment imaging instruments, the CASIA SS-1000 (Tomey Corp., Nagoya, Japan) and Pentacam (OCULUS, Arlington, WA) in measuring anterior segment parameters. METHODS: Single-center, prospective clinical trial. Participants ≥20 years of age were included. One eye was randomly selected, each imaged by three CASIA SS-1000 devices and three Pentacam devices by three different examiners. Each photographer operated a pair of devices, one CASIA SS-1000 and one Pentacam. The image order for each participant was determined by a random permutation table. Three images were taken from each device. A total of 18 images were taken for each eye. Ratios of the standard deviations, referenced as (CASIA/Pentacam), were calculated to compare the repeatability and reproducibility of the two imaging instruments. RESULTS: In all, 66 participants with a mean age of 46.4 years (±21.7) were enrolled in the study. All repeatability ratios and intra-device variability were less than 1 (anterior corneal curvature: flat = 0.86, steep = 0.85; posterior corneal curvature: flat = 0.43, steep = 0.61; and map: thinnest = 0.22; central = 0.24, 2 mm = 0.26, 4 mm = 0.27, and 6 mm = 0.30). All reproducibility ratios, which measure the inter-device variability, were less than 1 (anterior corneal curvature: flat = 0.58, steep = 0.73; posterior corneal curvature: flat = 0.25, steep = 0.31; and pachymetry map: thinnest = 0.20; central = 0.20; 2 mm = 0.20; 4 mm = 0.19; and 6 mm = 0.22). A ratio of less than 1 indicates that the CASIA SS-1000 has more consistent measurements. CONCLUSIONS: The CASIA SS-1000 was found to have better repeatability and reproducibility compared to the Pentacam for both corneal curvature and pachymetry maps. This greater consistency may require further study to determine whether the decreased variability can be translated into improved clinical results.

Repeatability and agreement of two anterior segment OCT in myopic patients before implantable collamer lenses implantation.

AIM: To evaluate the intra-operator repeatability of time domain and swept-source Fourier domain anterior segment optical coherence tomography (AS-OCT), namely, Visante AS-OCT and Casia SS-1000 OCT, in measuring the preoperative parameters of implantable collamer lens (ICL) in myopic eyes, as well as the agreement between the two devices. METHODS: A total of 97 eyes from 49 myopes were investigated in this prospective case series study. The anterior chamber depth (ACD), angle-to-angle distance (ATA), pupil diameter (PD) and crystalline lens rise (CLR) in all subjects were measured for three times during one session by the same operator. The repeatability was evaluated using the within-subject standard deviation (Sw), repeatability limits and intraclass correlation coefficients (ICC). The agreement between the two systems was evaluated using the Bland-Altman plots and 95% limits of agreement (LoA). RESULTS: The repeatability limits of Visante AS-OCT in measuring ACD, ATA, PD and CLR were 0.099, 0.141, 0.304, and 0.079 mm, respectively. The repeatability limits of Casia SS-1000 OCT in measuring ACD, ATA, PD, and CLR were 0.105, 0.127, 0.357, and 0.082 mm, respectively. Excellent repeatability could be attained in both devices, with the ICC>0.8 for all the measured variables. The interdevice agreement was excellent (P>0.05) for ACD and ATA, but poor (P<0.05) for PD and CLR. CONCLUSION: Good repeatability can be attained by time domain and swept-source Fourier-domain OCT for all the measured variables. Moreover, interdevice agreement analysis suggests that interchangeable measurements between two devices can be achieved for ACD and ATA, but not for PD and CLR; but the differences in measurements were not clinically significant.

Comparison of corneal thickness measured by CASIA SS-1000 OCT and Sirius anterior eye assay system / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare CASIA SS-1000 and Sirius OCT sweep anterior segment analyzer instrument for measuring normal corneal vertex thickness (CCT) and the thinnest corneal thickness (TCT) results the difference,correlation and consistency,and provide a theoretical basis for clinical application.METHODS:This was a prospective study.A total of 34 normal subjects were collected.The subjects were measured by the same skilled operator.The SS-1000 OCT was first used,and then the corneal thickness was measured repeatedly by Sirius anterior segment analyzer.Paired t test and Bland-Altman were used to evaluate the consistency of corneal apex and corneal thinnest point between SS-1000 OCT and Sirius anterior segment analyzer.RESULTS:The mean corneal apex measured by SS-1000 OCT and Sirius corneal topography were 517.62± 25.29μm and 518.47±27.23μm CCT,respectively.The thinnest points of SS-1000 OCT and Sirius anterior segment analyzer CCT were 513.53±25.06μ m and 515.32± 26.69μm,respectively.Paired t test showed that the difference on corneal thickness of vertex was not statistically significant (P＞0.05),but the thinnest corneal thickness was statistically significant (P＜ 0.05).Pearson analysis of the two devices,the correlation is 0.969,0.965.The results of 95％ consistency limiting analysis on the corneal vertex thickness by Bland-Altman was (-14.22μm,12.52μm),that of the thinnest corneal thickness was (-15.61μm,12.03μm),4％ (3/68) was out of the 95％ consistency limiting,but the thinnest corneal thickness was of a little larger differences.CONCLUSION:SS-1000 OCT measurement of CCT and Sirius anterior segment analyzer is highly consistent,in clinical work can be considered alternative,but the thinnest point of the cornea can not be replaced each other.