Purpose To assess the agreement between the Pentacam HR and the Sirius Scheimpflug analyzer in the anterior chamber, topographic, and corneal aberration parameters and to assess the repeatability of the measurements of each device in patients with keratoconus (KC). Patients and methods This prospective cross-sectional study included patients with a confirmed diagnosis of KC. Four reliable scans were obtained by the Sirius Scheimpflug analyzer and the Pentacam HR by a single operator in the same session. The anterior chamber, keratometric, pachymetric, and corneal aberration parameters were analyzed. Repeatability was assessed by calculating the within-subject standard deviation, test-retest repeatability, and within-subject coefficient of variation. Agreement was assessed using the intraclass correlation coefficient. Bland-Altman plots were used to determine the 95% limits of agreement between the two devices. Results A total of 68 eyes of 68 patients were included in this study. Both devices showed high repeatability (coefficient of variation <1%) for all studied keratometric and pachymetric parameters. Both devices demonstrated poor repeatability for all aberrometric parameters, with coefficients of variation exceeding 1%. The limits of agreement were also wide. Specifically, posterior flat keratometry showed the largest range (−28.82–26.96), followed by posterior steep keratometry (−36.27–29.53), thinnest corneal location (−20.47–34.39), and central corneal thickness (−26.34–22.94). Conclusion The Pentacam HR and Sirius Scheimpflug devices showed good repeatability in anterior segment parameters except for aberrometric measurements. Measurements between the two devices exhibited poor agreement. Consequently, we recommend using the same device for monitoring KC patients.
Ashour et al. (Thu,) studied this question.