Clinical comparison of the XPERT non-contact tonometer and the conventional Goldmann applanation tonometer

Intraocular pressure (IOP) in the right eye of 113 patients was measured with one XPERT NCT air-puff non-contact tonometer (XPERT) and compared with IOP measured with one Goldmann applanation tonometer (GAT). Precision of the methods was judged by variance analysis, indicating that GAT was slightly more precise than XPERT. The slope of the linear relationship between the methods did not differ significantly from 1.0. Mean difference between the methods was 0.92 mmHg, XPERT measuring lower than GAT, p = 0.00017. The intra-individual difference between methods ranged from -8.00 to 8.67 mmHg, and standard deviation (SD) of differences was 2.52 mmHg. The 95% limits of agreement between the two methods were -5.85 to 4.01 mmHg. The SD of differences is of approximately the same size as previous XPERT vs GAT as well as previous GAT vs GAT studies.