How to Calibrate a Goldmann Tonometer

Eye-care professionals use the Goldmann tonometer to measure fluid pressure inside the eyes of their patients. Elevated pressure in the eye is a warning sign of glaucoma. An ophthalmologist must calibrate the tonometer in order for it to function properly and obtain accurate measurements. In a matter of minutes, an ophthalmologist can calibrate the Goldmann tonometer, making it possible to recalibrate the instrument for every patient.

Things You'll Need

• Goldmann tonometer
• Prism case

Show More

Instructions

• 1

  Place the tonometer on a flat surface such as a table.

• 2

  Check dial position 2. Turn the tonometer over. You will notice several markings on the back. To check calibration, make sure the marking on the dial aligns with positions 2 and 6 when the appropriate check weights are applied. Remove the 2-gram weight from the prism case. Place the weight in the calibration arm of the tonometer.

• 3

  Turn the dial to 2. You will notice the arm move up and down. At dial position 0, the calibration arm should be in free movement. If the dial is turned backward or forward, the arm will move up and down.

• 4

  Turn the dial, and experiment with the arm. You will know the calibration is correct when the arm is horizontal at positions 1.9, 2 and 2.1.

• 5

  Turn the tonometer over. The mark from the dial should be aligned with the 2 mark on the back of the device.

• 6

  Check position 6. Place the 6-gram weight in the holder of the calibration arm. Turn the dial to position 6, and then move the dial slightly forward and backward to the equivalent of 5.9 and 6.1. The calibration arm should remain horizontal. Turn the tonometer over, and look at the position markers on the back. The dial marker should align with position 6.