Comparative study of intraocular pressure measurements by Goldmann applanation tonometer, noncontact tonometer and TonoPen
Abstract
The purpose of the study was to compare the levels of the intraocular pressure (NOT) measured in one eye at the same moment by three different methods: by Goldmann applanation tonometer (AT), non-contact tonometer (BT) and Tono-Pen (TP). It was further set the average variability of the performed measurements for particular tonometric methods.
Methods: NOT was assessed in 106 eyes of 106 subjects aged 7-77 years (average 34.3 +- 17.1 years). NOT was measured at the same moment with BT, TP and AT.
The obtained data were statistically analyzed. Results: The average NOT was 16.55 +- 2.95, 17.95 +- 4.47 and 16.13 +- 3.4mmHg when AT, BT and TP were applied.
Average variability of three measurements for AT, BT and TP was 1.51 +- 0.96, 1.78 +- 1.08 and 1.47 +- 0.9 mmHg. Average NOT levels of the measured AT and TP were almost identical with a difference of 0.42 mmHg (p = 0.236).
Average level of the intraocular pressure measured by BT was higher by 1.40 mmHg and 1.82 mmHg in comparison with AT and TP (p = 0.00002), respectively. Conclusion: NOT measurement produced almost identical average levels at AT and TP, whereas at BT the levels were much higher.
Average variability of the three subsequent NOT measurements was the highest at BT, whereas at AT and TP the average variability was lower and nearly identical.