Agreement among Goldmann applanation tonometer, iCare, and Icare PRO rebound tonometers; non-contact tonometer; and Tonopen XL in healthy elderly subjects.

Abstract

To evaluate the inter-device agreement among the Goldmann applanation tonometer (GAT), iCare and Icare PRO rebound tonometers, non-contact tonometer (NCT), and Tonopen XL tonometer. Sixty healthy elderly subjects were enrolled. The intraocular pressure (IOP) in each subject's right eye was measured thrice using each of the five tonometers. Intra-device agreement was evaluated by calculating intraclass correlation coefficients (ICCs). Inter-device agreement was evaluated by ICC and Bland-Altman analyses. ICCs for intra-device agreement for each tonometer were >0.8. IOP as measured by iCare (mean±SD, 11.6±2.5mmHg) was significantly lower (p<0.05) than that measured by GAT (14.0±2.8mmHg), NCT (13.6±2.5mmHg), Tonopen XL (13.7±4.1mmHg), and Icare PRO (12.6±2.2mmHg; Bonferroni test). There was no significant difference in mean IOP among GAT, NCT, and Tonopen XL. Regarding inter-device agreement, ICC was lower between Tonopen XL and other tonometers (all ICCs<0.4). However, ICCs of GAT, iCare, Icare PRO, and NCT showed good agreement (0.576-0.700). The Bland-Altman analysis revealed that the width of the 95% limits of agreement was larger between the Tonopen XL and the other tonometers ranged from 14.94 to 16.47mmHg. Among the other tonometers, however, the widths of 95% limits of agreement ranged from 7.91 to 9.24mmHg. There was good inter-device agreement among GAT, rebound tonometers, and NCT. Tonopen XL shows the worst agreement with the other tonometers; therefore, we should pay attention to its' respective IOP. Japan Clinical Trials Register; number: UMIN000011544.