Comparison of different keratometers with the EyeSys videokeratoscope

Abstract

ABSTRACT. We compared the accuracy and the reproducibility of the measurements using a Haag-Streit, a Shin-Nippon, and a Carl Zeiss keratometer and an EyeSys videokeratoscope. Two investigators performed 20 measurements on 3 calibrated steel balls and 5 measurements on 22 normal corneas with all instruments. Calculating the accuracy of the measurements the limits of the 95% confidence intervals of the bias were determined. The accuracy was better than ∫0.1D for the keratometers, whereas it was better than ∫0.25D for the EyeSys videokeratoscope. The coefficient of reproducibility (1.96¿standard deviation) on test balls and corneas was smaller than 0.25D in the case of the Shin-Nippon and Carl Zeiss keratometers and the EyeSys videokeratoscope whereas it was between 0.25-0.5D in the case of the Haag-Streit keratometer. The Carl Zeiss keratometer was the best with respect to the accuracy and reproducibility of the measurements. Paired t-test was used to find possible significant differences between the results of the two investigators, but only clinically insignificant differences were found.

Topography-based assessment of anterior corneal curvature and asphericity as a function of age, sex, and refractive status

“…The results in previous validation studies of the EyeSys videokeratoscope [13][14][15][16] are inconsistent. In addition, all these studies used the EyeSys Vista model (EyeSys Vision, Inc.) and it is not clear whether the reconstruction algorithm of that device was the same as that that of the iTrace wavefront analyzer with integrated EyeSys videokeratoscope device used in the present study.…”

Evaluation of Normal Corneas Using the Scanning-Slit Topography/Pachymetry System

“…3,18,[29][30][31] Anterior surface values in this report, such as minimum, maximum, and astigmatic keratometry, and axial power diopters were similar to previous reports performed by either conventional keratometry and topography or by Orbscan topography. 17,20,24,32 The central corneal thickness was 593.7 ± 54.19 µm, and the thinnest pachymetry value was 578 ± 50.53 µm with a significant thickening towards the 3-mm midperipheral region. Previous papers reported on similar Orbscan pachymetry data.…”

Accuracy and Precision of EyeSys and Orbscan Systems on Calibrated Spherical Test Surfaces

“…As a deviation greater than Ϯ 0.05 mm is needed to consider clinical significance, it can be stated that the accuracy of both instruments theoretically suits the practical requirements using test surfaces and not real corneas. 13,24 The reproducibility (COR) of the measurements carried out with EyeSys was clinically acceptable in all balls tested. The COR of the Orbscan was found to be between 0.01 and 0.13 mm, corresponding with the steepest and flattest balls, respectively.…”