How to Measure With an Applanation Tonometer

Applanation tonometry is a test performed by eye care specialists. Using an applanation tonometer, an optometrist can measure the pressure of the fluid inside your eye. As a diagnostic tool, it can detect glaucoma. This procedure is often part of a routine eye examination.

Things You'll Need

• Applanation tonometer
• Tonometer prism
• Anesthetic eye drops
• Fluorescent eye drops
• Slit lamp

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Instructions

• 1

  Explain the procedure to the patient. Establish that your patient is able to hold his head in position for the procedure. Instill anesthetic drops then fluorescent drops into both of your patient's eyes.

• 2

  Line up the zero and 180 points on the prism with the corresponding markers on the prism holder.

• 3

  Position your patient comfortably. Her head should be securely resting in place. This will prevent any unwanted movement during the procedure. Ask your patient look straight ahead, with both eyes open.

• 4

  Set the reading adjustment dials on the side of the tonometer to zero.

• 5

  Move the tonometer toward the patient's eye. Stop when the prism tip is touching the patient's eye.

• 6

  Turn the pressure dials to slowly increase the pressure of the prism on the eye. Stop turning the dials when two half circle images are visible through your observation lenses. The two half circles should be opposing with their edges lined up and touching each other.

• 7

  Remove the prism from your patient's eye. Multiply your result by 10. Document your findings in millimeters of mercury.

• 8

  Repeat the same procedure on the other eye.