Comparison of the iCare rebound tonometer and the Perkins applanation tonometer in children under general anesthesia

Abstract

The goal of the study was to compare Perkins applanation tonometry and iCare rebound tonometry, evaluating their correlation and agreement in a diverse pediatric population under general anaesthesia (GA). Children undergoing an eye examination under GA between November 2019 and March 2020 were included. Intraocular pressure (IOP) was measured successively using the Perkins applanation tonometer and the iCare IC200 rebound tonometer. Ultrasonic central pachymetry and axial length were measured. One hundred and thirty-eight eyes of 72 children were included. The mean age was 2.87years. IOP measurements obtained with the two tonometers were statistically and significantly highly correlated (r=0.8, P<0.001), although the iCare overestimated IOP by an average of 3.37mmHg (SD±4.48). The agreement between the two methods was moderate; the 95% agreement limits ranged from -5.41 to +12.15mmHg (r=0.5, P<0.001). The IOP difference between the two tonometers was weakly but significantly correlated with mean IOP (r=0.52; P=0.006). No correlation was found with axial length and pachymetry. In this study, the IOP values obtained using the Perkins applanation tonometer and the iCare IC200 rebound tonometer were well correlated. The iCare tended to overestimate the IOP, especially for high IOP values. However, no underestimation of IOP was found with this device, hence its potential for glaucoma screening in children.