How is calibration of the applanation tonometer checked?

The correct method for checking the calibration of an applanation tonometer involves utilizing a measured weight attached to the tonometer balancing arm at specific points, such as 0, 2, and 6. This procedure ensures that the tonometer is properly calibrated to measure intraocular pressure accurately. The use of a standardized measured weight allows for a precise assessment of the tonometer's performance at various pressure levels, validating its accuracy and reliability when measuring eye pressure.

Calibration through this method is vital because the tonometer must provide consistent and accurate readings for effective diagnosis and treatment of eye conditions, such as glaucoma. By confirming that the tonometer balances correctly with known weights, eye care professionals can trust the readings obtained during patient assessments.

In contrast, visual inspection of the measurement scale does not provide a quantitative verification of the device’s accuracy. While this might help identify obvious physical damage, it cannot ensure the device is functioning correctly at specific pressure levels. Similarly, using a standard calibration fluid is not applicable to applanation tonometers, as they measure pressure based on indentation, rather than fluid characteristics. Adjusting the tension manually could introduce human error and variability, which compromises the reliability of the readings, making it an unsuitable method for calibration verification. Thus, using a measured