Rebound tonometer compared with goldmann tonometer in normal and pathologic corneas

To compare the intraocular pressure (IOP) measurements obtained with the rebound tonometer (RT) and the Goldmann handheld tonometer (GT) in normal and altered corneas.

A total of 208 normal corneas and 50 corneas with pathologies were included in this prospective study. All measurements were randomly obtained by 1 observer. The medians and interquartile range (IR) for both tonometers were compared. The median differences were assessed in IOP groups. Agreement between the tonometers was calculated using the Bland-Altman method.

The median IOP in all eyes was 17 mm Hg (IR, 13-22 mm Hg) with the RT and 16 mm Hg (IR, 13-21 mm Hg) with the GT (P < 0.001). The correlation was excellent between tonometers (r2 = 0.86; P < 0.001). The minimal differences between the two were obtained from 10 to 20 mm Hg (GT). The Bland-Altman scatterplot obtained good agreement between the instruments. In normal corneas, the median difference was < or =2 mm Hg in 77.4% of cases. In the altered corneas, the median difference was < or =2 mm Hg in 73% of cases (P = 0.21 compared with the normal group). In 10% and 2% of cases, the IOP could not be measured using the GT and RT, respectively.

The results were similar for both tonometers. In the altered corneas, the IOP could be difficult to obtain with the GT because of distorted half-circles. The 1-mm-diameter disposable RT tip facilitated obtaining measurements without anesthetic drops, which avoids infections. The RT could be useful in routine clinical settings when measuring IOP in corneas with pathologies.