Comparison of a New Scheimpflug Camera and Swept-Source Optical Coherence Tomographer for Measurements of Anterior Segment Parameters

Abstract

Introduction This study evaluated the differences and agreement between a new Scheimpflug camera (Scansys) and a swept-source anterior segment optical coherence tomographer (CASIA 2) for measurements of the anterior segment of the eye in normal subjects. Methods This prospective study included 84 eyes from 84 normal adult subjects who underwent three consecutive measurements with the Scansys and the CASIA 2 in random order. The mean keratometry (Km), astigmatism magnitude (AST), J 0 , and J 45 vectors for both anterior and posterior corneal surfaces, central corneal thickness (CCT), thinnest corneal thickness (TCT), and anterior chamber depth (ACD) were obtained by both devices. The difference between these two devices was assessed using paired t test and violin plots. Bland–Altman plots and 95% limits of agreement (LoAs) were used to evaluate agreement. Results No statistically significant differences between the two devices were found for the anterior AST, anterior J 45 , and posterior J 45 ( P > 0.05). The remaining parameters were statistically significant ( P ≤ 0.05), but the differences not clinically significant. The violin plots showed that the distribution and probability density of the measured parameters were similar for both devices. Bland–Altman plots revealed high agreement for the measured parameters between the Scansys and CASIA 2, with narrow 95% LoAs. Conclusions In terms of assessing parameters for the anterior segment, our study indicated that Scansys and CASIA 2 generally showed significant agreement. The two devices used in this study’s assessment of all the parameters can be used interchangeably in refractive analysis.

Comparison of axial length and anterior segment parameters of patients with myopia measured using 2 fourier-domain optical coherent biometry devices

“…Liao et al [ 16 ] and Cheng et al [ 17 ] compared IOLMaster 700 with OA-2000 (also based on SS-OCT), pointing out that they had maximum absolute 95% LoA of 24.67 μm and 24.40 μm, respectively, similar to those in our study. A highly accurate corneal thickness measurement can be obtained using the Fourier-Domain OCT technology, as it can better distinguish the anterior and posterior corneal interfaces [ 18 ]. For CCT measurements, a mean deviation of 1.748 μm, as calculated using the Olsen or Kane formula, would result in a refractive power change of less than 0.005 D for artificial IOLs, [ 19 ] rendering it clinically insignificant.…”