Influence of artificial tears on corneal parameter measurement using three different devices: Keratometry and Scheimpflug technology, a randomized trial.

Abstract

Purpose: To evaluate the effect of artificial tear (AT) application on the repeatability of corneal parameters with three different devices.

Methods: In this prospective, randomized clinical trial, 145 patients were measured with one of three devices in the Department of Ophthalmology, Goethe University, Frankfurt, Germany. Two baseline measurements and four measurements following AT application after 30 s, 2, 5 and 10 min were performed.

Results: Forty-eight eyes were measured with the IOLMaster 700 (Carl Zeiss Meditec AG, Oberkochen, Germany) and Galilei G6 (Ziemer, Port, Switzerland), and 49 with the Pentacam AXL (Oculus, Wetzlar, Germany) (145 total). Repeatability of the mean corneal power (K_m) between baseline measurements was high (0.049 ± 0.008 D for IOLMaster, 0.061 ± 0.011 for the Pentacam AXL and 0.065 ± 0.009 for Galilei G6) but significantly variable after 30 s and 2 min for IOLMaster 700 (0.177 ± 0.021 D, p < 0.001 and 0.079 ± 0.009, p = 0.004) and Galilei G6 (0.163 ± 0.020 D, p < 0.001 and 0.119 ± 0.014 D, p = 0.003). K_m differed significantly from baseline at 30 s, 2 and 5 min with Pentacam AXL (0.215 ± 0.041 D, p < 0.001; 0.157 ± 0.025 D, p < 0.001 and 0.094 ± 0.012 D, p = 0.007). Variability was highest at 30 s and decreased over time.

Conclusion: The use of AT leads to high variability of keratometric measurements for each device. This should be considered after use, and at least 5 min should elapse before measurements.