Two Types of Tonometer Vary in IOP Readings

■ Japanese researchers led by Shunsuke Nakakura, MD, PhD, set out to determine whether there was agreement between the IOP values recorded by the new rebound tonometers, Icare ic100 and Icare TA01i, compared to the Goldmann applanation tonometer (GAT). The researchers studied 1 eye each of 106 subjects (57 with POAG and 49 healthy subjects). IOP was randomly measured twice with the patient in sitting position using the Icare ic100, Icare TA01i, and GAT. Tonometer measurements were evaluated using Bland-Altman analysis. The IOPs measured using Icare ic100, Icare TA01i, and GAT were 11.7±3.0, 12.2±2.9, and 16.0±3.2 mmHg, respectively. Icare ic100 showed significantly lower IOPs than GAT, but not significantly lower than Icare TA0li. Bland-Altman analysis revealed that the mean differences between Icare ic100 and Icare TA01i and those between Icare ic100 and GAT were −0.46 and −4.2 mmHg, respectively.

The researchers concluded that the new rebound tonometer Icare ic100 almost constantly showed IOPs lower than GAT. They found that the difference was affected by CCT, corneal curvature, and disease. The study was published in a recent issue of the Journal of Glaucoma.