Prevalence of calibration errors in goldmann applanation tonometers

Area of Science:

• Ophthalmology
• Medical Device Calibration
• Glaucoma Diagnosis

Background:

• Goldmann applanation tonometry is a standard method for measuring intraocular pressure.
• Accurate calibration of tonometers is crucial for reliable glaucoma diagnosis and management.
• Previous studies have indicated potential issues with tonometer calibration, necessitating further investigation.

Purpose of the Study:

• To assess the prevalence of calibration errors in Goldmann applanation tonometers.
• To quantify the extent of calibration deviations from manufacturer specifications.
• To identify the proportion of tonometers falling outside acceptable calibration limits.

Main Methods:

• A cross-sectional study was conducted at Farabi Eye Hospital.
• All in-use Haag-Streit Goldmann applanation tonometers were evaluated.
• Calibration was checked by independent observers using the manufacturer's protocol, with a third observer for discrepancies.

Main Results:

• Out of 43 evaluated Goldmann tonometers, significant calibration errors were found.
• 93% of tonometers deviated by more than ±0.5 mmHg from the recommended calibration.
• 28% of devices exceeded the acceptable ±2.5 mmHg calibration error margin.

Conclusions:

• A substantial majority of Goldmann tonometers at the hospital exhibited calibration errors beyond the manufacturer's recommended range.
• A notable percentage of tonometers were outside the clinically acceptable calibration limits.
• Further research is recommended to explore the clinical implications of these calibration inaccuracies.