A tonometer is the equipment used to measure the pressure inside the eyes, also known as intraocular pressure (IOP). Tonometry is rarely performed at an average comprehensive eye exam unless the patient is at high risk of glaucoma or has already been diagnosed.

Fortunately, tonometry can detect changes in eye pressure before they cause any symptoms, enabling prompt action to be taken before the patient’s vision is affected.

About glaucoma

Glaucoma is a common eye condition that occurs when the optic nerve, which connects the eye to the brain, becomes damaged. It is usually caused by fluid building up in the front part of the eye, which causes the pressure inside the eyes to build. As this pressure increases, the optic nerve becomes increasingly damaged, preventing messages from being transmitted between the eyes and brain effectively. As a result, the patient’s vision becomes compromised. Without treatment, vision loss will continue to increase. Unfortunately, any vision lost as a result of glaucoma cannot be restored.
 

Most of the time, glaucoma develops very slowly, which means that many people don’t realize that they are affected until some damage to their vision has already occurred. However, occasionally glaucoma can develop quickly, and symptoms do occur. These can include:

• Red eyes
• Intense headaches
• Tenderness around the eyes
• Eye pain
•  Seeing rings/halos around lights
• Blurred vision
• Nausea and vomiting

If you notice any of these symptoms, make an appointment with your eye doctor right away so that you can be assessed. You are likely to have a tonometry test as part of this assessment.
 

What to expect from tonometry testing

There are various methods of tonometry testing, but many eye doctors use either Goldmann tonometry, which is the conventional technique to measure eye pressure, or electronic tonometry.

Goldmann tonometry testing uses the Goldmann applanation tonometer attached to a slit lamp microscope. This requires anesthetic eye drops to be used, which numb the eyes. Then, a small probe is pressed gently against the eye, indenting the cornea. The pressure that the cornea pushes back onto the tonometer is what is measured to give your IOP reading.

Electronic tonometry is where a handheld, mobile device is gently and quickly applied to the cornea to check the pressure, providing an accurate reading. Some eye doctors also offer non-contact tonometry, where a puff of air is used to flatten the cornea, although this is reported to be less accurate than the Goldmann technique.

If you want to learn more about tonometry testing, please call our office to speak with our dedicated eyecare professionals.