Comparison of keratometric values of healthy eyes measured by javal keratometer, nidek autokeratometer, and corneal analysis system (EyeSys)

In this study we compare three different keratometric methods normally used in contact lens fitting to assesses the effect of contact lenses on corneal curvature. Measurements were obtained from 100 normal eyes using a Javal ophthalmometer, an Nidek autokeratometer, and Corneal Analysis System (EyeSys) to compare the keratometric readings obtained by these three instruments. Using regression analysis and bias (the mean of the difference compared with zero), we found good agreement among the instruments. However, the 95% confidence limits showed a lack of agreement between them. Although the differences between instruments were clinically acceptable, relevant differences were found using the 95% confidence limits. We should not assume that the results of the different keratometric systems can be interchanged in contact lens fitting and follow-up examinations.