Open AccessComparison of different keratometers with the EyeSys videokeratoscope
Author(s) -
Vámosi Péter,
Sohajda Zoltán,
Módis László,
Vámosi György,
Berta András
Publication year - 1998
Publication title -
acta ophthalmologica scandinavica
Language(s) - English
Resource type - Journals
eISSN - 1600-0420
pISSN - 1395-3907
DOI - 10.1034/j.1600-0420.1998.760207.x
Subject(s) - keratometer , reproducibility , medicine , confidence interval , limits of agreement , ophthalmology , coefficient of variation , standard deviation , optometry , statistics , nuclear medicine , mathematics , cornea
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 x 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.