Repeatability of the Pentacam HR and IOLMaster 700 in Patients With Keratoconus and Intracorneal Ring Segments

Purpose: To determine the repeatability of the Pentacam HR (Oculus Optikgeräte GmbH) and IOLMaster 700 (Carl Zeiss Meditec AG) in patients with keratoconus and intracorneal ring segments (ICRS) implantation. Methods: The setting of this cross-sectional and observational study was the Fundación de Oftalmología Médica de la Comunitat Valenciana, Valencia, Spain. Eyes were scanned three consecutive times on each device. Repeatability was assessed using within-subject standard deviation (Sw), within-subject coefficient of variation (CVw), repeatability index (R), and intraclass correlation coefficient (ICC). Agreement between devices was evaluated with Bland-Altman plots and 95% limits of agreement (LoA). The sample was divided into two (lower and higher keratometry groups) to evaluate differences according to the severity of keratoconus. Results: The study comprised 131 eyes of 100 patients. The repeatability of all parameters for both devices was excellent (ICC > 0.9 and low Sw), Bland-Altman analysis revealed wide 95% LoA, indicating clinically relevant differences between devices. A slight decrease in repeatability was observed in the higher keratometry group for flat keratometry in the IOLMaster 700 (ICC = 0.894) and ACD in the Pentacam HR (ICC = 0.895). Keratometry Sw and R values in both devices were slightly higher in the higher keratometry group. Conclusions: The Pentacam HR and IOLMaster 700 showed high repeatability in patients with ICRS. However, the wide 95% LoA indicate poor agreement between devices and hence they cannot be used interchangeably in clinical practice. A slight decrease in repeatability could be expected in eyes with higher keratometry.