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

Purpose: To evaluate the influence of keratometric measurements on the conc ordance of intraocular pressure (IOP) readings with three applanation tonom eters. Patients and Methods: The IOPs of 404 eyes of 202 patients from a general e ye clinic were measured by Goldmann, Tone-Pen XL, and noncontact Nidek NT 2 000 tonometers. Differences in the TOP measurements between Goldmann and th e other two tonometers (Delta IOPG-TP and Delta IOPG-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 Delta IOP and keratometry measures was also performe d. Right and left eyes were analyzed separately. Results: The IOP readings taken with the Goldmann tonometer were significan tly higher than those taken with either of the other two tonometers within the overall study population. The Delta IOP within the three keratometric s ubgroups was not statistically significant except for Delta IOPG-TP in the right eyes. Regression analysis showed that keratometry and Delta IOPG-TP a nd Delta IOPG-NCT had a significant but very weak coefficient of correlatio n in the right eye, but not in the left. Conclusion: Corneal curvature within the normal range does not have a clini cally significant influence on the concordance of IOP readings obtained wit h Goldmann and Tone-Pen or noncontact tonometers.