Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers.

ABSTRACT

PURPOSE: To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers. PATIENTS AND METHODS: The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately. RESULTS: The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left. CONCLUSION: Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.