Agreement of total corneal power measured by CASIA 2, Pentacam AXL, and IOLMaster 700 in normal and keratoconic patients

Abstract

Purpose: To evaluate agreement of total corneal power (TCP), ocular biometry and IOL power calculation measured by CASIA 2, Pentacam AXL, and IOLMaster 700 in normal and keratoconic patients Setting: King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, Thailand Design: Prospective observational study Methods: One-hundred normal eyes and 34 keratoconic eyes were enrolled. Biometric values were measured by each device for three times by two operators to evaluate repeatability and reproducibility of TCP and other parameters. The agreement of TCP and other parameters including total corneal astigmatism, anterior keratometry, anterior corneal astigmatism, posterior keratometry, posterior corneal astigmatism, anterior chamber depth, white-to-white (WTW) corneal diameter, central corneal thickness, and intraocular power were evaluated. Intraclass correlation coefficient and Bland Altman plot was used to analyze. Results: The repeatability and reproducibility of TCP and other biometry were high in all devices except WTW (ICC > 0.9). The agreement of TCP was excellent among three devices in both groups (ICC > 0.9). However, the agreement of TCP between CASIA 2 and IOLMaster 700 was slightly lower in normal eyes (ICC = 0.867) and keratoconic eyes (ICC = 0.852) with mean differences more than 1.0 diopter, might be considered clinically significant. Wider 95% limit of agreement were found in keratoconus group. Most of the other parameters and IOL power showed good to excellent agreement except WTW showing poor to moderate agreement in both groups. Conclusions: The agreement of TCP by CASIA 2, Pentacam AXL, and IOLMaster 700 was excellent in normal and keratoconic eyes. However, TCP cannot be used interchangeably.