How to Use a Tonometer: A Step-by-Step Guide

The experts at Mainline Instruments have compiled this practical guide, which explains how to use a tonometer effectively for eye care professionals and equipment buyers. This tonometer step-by-step guide covers preparation, method-specific procedures, IOP measurements and essential after-use checks. Always consult the manufacturer’s instructions, complete appropriate training and follow local clinical protocols to ensure safe, accurate and consistent measurements when using tonometry equipment.

What Is a Tonometer Used For?

A tonometer is used to measure intraocular pressure (IOP), an important part of routine eye health assessment and glaucoma monitoring. Measuring IOP can help clinicians identify pressure levels that may require further investigation or ongoing management.

For a broader explanation of tonometers, their types and how they work, see our “What Is a Tonometer?” guide.

Before Using a Tonometer: Safety and Preparation

Before taking an IOP measurement, be sure to confirm that the patient is suitable for testing. Ask them about any recent eye surgeries, corneal problems, discomfort, eye infections and even if they are still wearing contact lenses.

Explain the procedure, obtain appropriate consent and ensure the patient is comfortable. 

Check the tonometer is powered and correctly configured, with a suitable probe or tip fitted. 

Confirm cleanliness and, where applicable, complete the device’s self-check or calibration procedure before use, following manufacturer instructions and local clinical protocols.

How to Use a Rebound Tonometer

A rebound tonometer uses a lightweight probe that briefly comes into contact with the cornea, allowing said device to calculate the intraocular pressure. Handheld tonometers are designed for quick, convenient measurements in a clinical or healthcare setting. Devices like an iCare tonometer, should always be positioned in the correct manner, use the recommended probe and technique and any other manufacturer instructions. 

Step 1: Insert a Single-Use Probe and Turn the Device On

Start by fitting a brand new, single-use probe for each and every patient in order to maintain good working hygiene and prevent cross-contamination. Insert it into the device correctly and switch on the tonometer.

Step 2: Position the Patient and Tonometer Correctly

Ensure the patient is comfortable and positioned securely before testing. Align the tonometer with the centre of the cornea and hold it steady during measurement. The iCare IC200 provides 200° positional freedom, making it suitable for seated, reclined or supine patients.

Step 3: Take the Measurement and Check Reading Reliability

Take the required measurement using the sequence best recommended for the specific tonometer you are using. There are some devices that require several readings to provide the optimal result. Check any reliability indicators, monitor any unusual readings and be sure to follow manufacturer guidance at all times.

Step 4: Record the Result and Dispose of the Probe

Record the IOP measurement for each eye, including the time, device or method used where relevant. Note any factors that could influence reliability. After testing, dispose of the probe appropriately and reset or prepare the tonometer ready for the next patient.

How to Use Different Types of Tonometer

Goldmann Applanation Tonometer

Prepare the patient with topical anaesthetic and fluorescein before positioning them at the slit lamp. Align the applanation prism with the centre of the cornea and use the appropriate illumination to view the fluorescein mires. Adjust until the mires meet correctly, then record the resulting IOP measurement.

Non-Contact Tonometer

Position the patient comfortably and ask them to focus on the instrument’s fixation target. Align the device with the eye before delivering a controlled air puff to estimate intraocular pressure. Several measurements may be taken to confirm consistency. Its quick, contact-free process makes non-contact tonometry particularly useful for high-throughput and screening options.

Tonometer Cleaning, Maintenance and Servicing

Routine cleaning, preventative maintenance and regular servicing are all important when learning how to use a tonometer. These processes are crucial for keeping your tonometer functioning correctly for accurate IOP measurements. Ensuring good equipment care like this will also minimise contamination risks. The experts here at Mainline can offer advice where needed, but where possible, following manufacturers recommended procedures can help.

Find the Right Tonometer for Your Practice

There is no blanket answer for what tonometer is best. This all depends on multiple factors around the precise needs of your practice, your workflow and patient requirements. Mainline is on hand to offer training and demonstrations on how to use a tonometer and to help you compare tonometry equipment, like the iCare tonometer range. Contact us today to find out more.

Frequently Asked Questions

Can tonometry be done without anaesthetic drops?

Yes, depending on the device being used. Rebound and non-contact tonometers can generally measure IOP without anaesthetic. Goldmann applanation tonometry normally requires topical anaesthetic because the measuring prism touches the cornea. Always use the method according to manufacturer instructions and clinical protocols.

Do iCare tonometers need calibration?

Calibration requirements depend on the specific iCare model. Many iCare tonometers are designed to minimise routine calibration, but users should still carry out recommended checks and arrange servicing when required. 

Refer to the manufacturer’s instructions to confirm the appropriate maintenance and calibration schedule for your device.

How many readings should you take with a tonometer?

The required number varies between tonometer types and individual models. Some instruments automatically collect several measurements to provide a reliable result, while others require the user to repeat readings.

What should you do if tonometer readings are inconsistent?

Check the patient’s positioning, fixation, device alignment and measurement technique before taking further readings. Review any reliability indicators and ensure the instrument is clean and functioning correctly. Repeat the measurement when appropriate, following manufacturer guidance.