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

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.

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.

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.

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.