Precision and accuracy of the ICare tonometer - Peripheral and central IOP measurements by rebound tonometry

The purpose of this study was to evaluate the ICare tonometers precision and accuracy and the extent to which intraocular pressure (IOP) measurements are influenced by measuring position.

This was carried out by comparing the central and peripheral ICare-IOP readings and comparing ICare- with the Goldmann applanation tonometer (GAT)-IOP readings. IOP was measured using the ICare rebound tonometer on the right eye of 40 subjects, straight at the centre of the cornea (CS), straight 2 mm from the nasal and temporal limbus (NS and TS), and in 10 degrees nasally and temporally angled positions measured from the same location as CS (NA and TA). The IOP was also assessed with the GAT.

Central IOP (CS) was significantly (p < 0.001) greater than peripheral measurements (NS, TS, NA and TA) by approximately 3-4 mmHg. Centre IOP (CS) significantly overestimated by mean 2 mmHg and the peripheral measurements significantly underestimates approximately 1.4-2 mmHg compared with GAT readings.

The ICare tonometer may be useful in a routine clinical setting for IOP screening, but the ICare measurement is not a substitute for the GAT measurement, when a precise and accurate IOP is desired.