Comparison of Portable Tonometers and Goldmann Applanation Tonometer for Intraocular Pressure Measurement

ABSTRACT

PURPOSE: To compare the intraocular pressure (IOP) measured by portable rebound tonometer and TonoPen applanation tonometer with pressure measured by Goldmann applanation tonometer (GAT) and analyze the factors affecting IOP disagreement between tonometers. METHODS: In a prospective study of 463 eyes, IOP was measured with Icare Pro(R) rebound tonometer, TonoPen AVIA(R) applanation tonometer, and GAT. Bland-Altman plot, intraclass correlation coefficient, Pearson's correlation analysis, and multiple regression analysis were performed to evaluate the agreement of IOP measured by each tonometer and the factors affecting the measurements. RESULTS: The IOP values measured by Icare Pro(R) and TonoPen AVIA(R) were consistently higher than those measured by GAT, but showed no significant differences with those measured by GAT (p = 0.307 and 0.114, respectively). In Bland-Altman plot, the IOP values measured by Icare Pro(R) and TonoPen AVIA(R) exhibited excellent agreement with those measured by GAT. Both Icare Pro(R)/GAT and TonoPen AVIA(R)/GAT differences increased with younger age (p = 0.041 and 0.049, respectively) and higher central corneal thickness (p = 0.019 and 0.035, respectively). CONCLUSIONS: IOPs measured by portable Icare Pro(R) rebound tonometer and TonoPen AVIA(R) applanation tonometer were significantly correlated with IOP measured by GAT. Therefore, such instruments can be useful when measuring IOP with GAT is difficult. However, central corneal thickness and age should be considered when measuring IOP with portable tonometers.