Purpose: The Icare® Home tonometer is a new rebound tonometer, developed for intraocular pressure (IOP) self-monitoring. The main objective of our study was to evaluate the reliability and reproducibility of measurements taken with the Icare® Home tonometer in glaucoma patients compared to the Goldmann applanation tonometer. A secondary objective was to investigate factors that could influence the reproducibility of these measurements.
Materials and methods: Fifty-two glaucoma patients were included in this prospective, non-randomized, monocentric study. IOP measurements were performed on the right eye and then on the left eye in the following order (3 measurements of IOP for each method): air tonometer (T-Air), Icare® Home tonometer by the patient (RT-P), Icare® Home tonometer by an ophthalmologist (RT-O), Goldmann applanation tonometer (GAT).
Results: Forty-four patients (85%) managed to take their IOP on both eyes with the Icare® Home tonometer. Mean IOPs were 14.35±3.93mmHg (T-Air), 13.43±4.65mmHg (RT-P), 14.13±4.29mmHg (RT-O), 14.74±3.84mmHg (GAT). The intraclass correlation indices (ICC) on the 3 repeated IOP measurements were 0.924, 0.872, 0.947 and 0.957, respectively. Bland-Altman analysis found a mean difference (bias) between GAT and RT-P, between GAT and RT-O, and between RT-O and RT-P, respectively, of 1.31, 0.61 and 0.70mmHg, with a 95% confidence interval of -3.34 to 5.96, -3.91 to 5.14 and -3.44 to 4.84mmHg, respectively. The reproducibility of the measurements taken with the Icare® Home tonometer did not vary according to corneal thickness or age of the patients.
Conclusion: The Icare® Home tonometer provides reliable and reproducible IOP values in glaucoma patients, although it appears to slightly underestimate the IOP measurements compared to the Goldmann applanation tonometer.