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

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.

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), J₀, and J₄₅ 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.

No statistically significant differences between the two devices were found for the anterior AST, anterior J₄₅, and posterior J₄₅ (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.

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.