Intradevice and Interdevice Agreement Between a Rebound Tonometer, Icare PRO, and the Tonopen XL and Kowa Hand-held Applanation Tonometer When Used in the Sitting and Supine Position.

PURPOSE: The aim of the study was to investigate the agreement between a new portable tonometer, Icare PRO, and the Tonopen XL and Kowa hand-held applanation tonometers (HAT). METHODS: The right eyes of 127 healthy subjects were enrolled. Intraocular pressure (IOP) was measured in both sitting and supine positions using the Icare PRO, Tonopen XL, and Kowa HAT tonometers. The repeatability of the IOP measurements was evaluated by calculating intraclass correlation coefficients. Between-method agreements of tonometer measurements were evaluated using Bland-Altman analysis. RESULTS: Intradevice agreement: The intraclass correlation coefficients (sitting, supine) of Icare PRO, Tonopen XL, and Kowa HAT were (0.863, 0.656), (0.845, 0.819), and (0.957, 0.956), respectively.Interdevice agreement: The Bland-Altman analysis revealed that, in the sitting position, the mean differences between Icare PRO and Tonopen XL, and between Icare PRO and Kowa HAT were -0.43 and 0.43 mm Hg, respectively (95% limits of agreement: -6.24 to 5.34 mm Hg, -4.04 to 4.90 mm Hg). In the supine position, the corresponding mean differences were -0.88 and 0.14 mm Hg (95% limits of agreement: -5.66 to 3.91 mm Hg, -4.06 to 4.33 mm Hg). IOP differences between Icare PRO and the other tonometers were unaffected by central corneal thickness. CONCLUSIONS: The repeatability of Icare PRO was slightly lower in the supine position than in the sitting position. Although Icare PRO underestimated IOP values in eyes with higher IOP when compared with Tonopen XL and Kowa HAT in both positions, we observed good interdevice agreement between Icare PRO and both Tonopen XL and Kowa HAT.

Intraocular pressure of supine patients using four portable tonometers.

PURPOSE: To evaluate the congruity of intraocular pressure (IOP) measurements from supine patients, which were obtained using four portable tonometers. METHODS: Intraocular pressure measurements were obtained from the right eye of 72 supine patients. We used the iCare (Tiolat Oy, Helsinki, Finland) rebound tonometer, the Diaton (BICOM Inc., Long Beach, NY) transpalpebral tonometer, the Tonopen XL (Reichert inc., Depew, NY), and a Kowa hand-held applanation tonometer (HAT; Kowa Company, Ltd., Nagoya, Japan). Relationships between mean IOPs were evaluated using Pearson correlation coefficients, and the mean differences between tonometers, using one-way analysis of variance followed by Tukey-Kramer post-hoc analysis. Levels of agreement were evaluated using Bland-Altman analysis. RESULTS: The mean IOPs (mean ± SD) were 18.2 ± 3.5 mm Hg for iCare, 14.8 ± 3.4 mm Hg for Diaton, 16.7 ± 3.7 mm Hg for Tonopen XL, and 16.8 ± 2.8 mm Hg for Kowa HAT. Pearson correlation coefficients between iCare, Tonopen XL, and Kowa HAT ranged from 0.382 to 0.577, whereas those between Diaton and other tonometers ranged from 0.041 to 0.286. Post-hoc analysis indicated significant differences between all pairs except Tonopen XL and Kowa HAT. The mean difference between measurements from iCare and Diaton was 3.39 ± 3.39 mm Hg; iCare and Tonopen XL, 1.47 ± 3.52 mm Hg; iCare and Kowa HAT, 1.49 ± 2.90 mm Hg; Diaton and Tonopen XL, -1.93 ± 4.90 mm Hg; Diaton and Kowa HAT, -1.90 ± 4.15 mm Hg; and Tonopen XL and Kowa HAT, 0.02 ± 3.61 mm Hg. Computation of the width of the 95% limits of agreement resulted in a wide bias range when comparing Diaton with all tonometers. Relatively good agreements were observed between iCare, Tonopen XL, and HAT. CONCLUSIONS: Intraocular pressure measurements obtained in a supine position by four portable tonometers were not interchangeable. Although iCare and Tonopen XL significantly overestimated IOP values in eyes with a higher IOP when compared with Kowa HAT, the agreements between iCare, Tonopen XL, and Kowa HAT were at clinically acceptable levels.