Agreement between the Icare HOME tonometer and the Goldmann Applanation Tonometry in the assessment of the Peak Intraocular Pressure in the Water-Drinking Test

Purpose: To investigate the agreement between the Icare HOME tonometer and the Goldmann Applanation Tonometry (GAT) in assessing the Peak Intraocular Pressure during the Water-Drinking Test (WDT).

Design: Prospective cross-sectional study.

Subjects: 79 eyes of 41 open-angle glaucoma patients were included in the study.

Methods: All of the included patients underwent a training session provided by ophthalmologist specialists to use the Icare® Home tonometer. Then the IOP was first measured with Goldmann applanation tonometry (AT900; Haag-Streit; Köniz, Suiça) by a trained physician, immediately followed by Icare® Home tonometry (TA022, iCare Oy, Vanda, Finland) measurement by the patient. Four measurements were taken with each device with 15 min difference as established by the WDT.

Main outcome measures: The agreement and degree of correlation of the peak IOP by both tonometers were assessed.

Results: The agreement between iCare and Goldmann Applanation Tonometer was high during the WDT: the intraclass correlation coefficient (r) between the two methods from basal to 45 min: 0.94 (p < 0.001), at basal: 0.91 (p < 0.001), at 15 min: 0.94 (p < 0.001), at 30 min: 0.94 (p < 0.001), at 45 min: 0.95 (p < 0.001) and for peak IOP: 0.94 (p < 0.001). There was no significant difference between peak IOP with GAT and iCare 18.3 ± 4.6 (10-33) and 18.5 ± 5.0 (0-33) (p = 0.533), nor between the delta of fluctuation between basal and peak IOP with GAT and iCare 3.96 ± 3.22 and 4.54 ± 3.92 (p = 0.054).

Conclusion: Our study demonstrated a high agreement between iCare HOME and Goldmann Applanation Tonometer during the WDT in a clinical environment with supervision.