Goldmann Applanation Tonometer Calibration Error Frequency

This study investigated how quickly Goldmann applanation tonometers used in clinical practice develop calibration errors and the frequency of checks required to detect these errors. Checks of the calibration error of all Haag-Streit Goldmann applanation tonometers at Month Zero, Month One, and Month Four were performed according to the Haag-Streit method using a standard calibration weight bar by two independent observers. Calibration errors were classed as +/- 0.5 to 2.5 mmHg, +/- 3 to 4 mmHg or greater than +/- 4 mmHg.