What the Air Puff Test Measures
The “air puff test,” or Non-Contact Tonometry (NCT), is a common procedure used in eye care. This test primarily measures intraocular pressure (IOP), which is the fluid pressure inside the eye. Maintaining a healthy range of IOP is important for the eye’s overall well-being.
IOP measurement is a routine part of a comprehensive eye examination, serving as a screening tool for certain eye conditions. Elevated intraocular pressure is a significant risk factor for glaucoma, a group of diseases that can damage the optic nerve. Early detection of increased IOP allows for timely intervention, preserving vision.
Performing the Test
During the air puff test, you will sit comfortably in front of a specialized instrument. Your chin will rest on a support, and your forehead will be placed against a headrest to stabilize your head. The eye care professional will align the machine with your eye.
You will be instructed to look straight ahead at a target light inside the machine. A gentle puff of air will then be released onto your open eye. This puff is quick and lasts only a fraction of a second. While some people might feel a slight surprise or blink reflex, the test is generally painless and involves no direct contact with the eye, apart from the air.
Interpreting Eye Pressure Readings
The air puff test provides a numerical reading that represents your intraocular pressure, measured in millimeters of mercury (mmHg). This reading reflects the resistance of your cornea to the puff of air. A healthy, “normal” range for IOP typically falls between 10 and 21 mmHg, though this can vary slightly among individuals.
A high reading from the air puff test is not a definitive diagnosis of an eye condition. Instead, it indicates that your eye pressure is elevated above the typical range. This elevation signals to your eye care professional that further diagnostic tests may be needed to determine the underlying cause and assess any potential risks to your vision.
What Happens After the Test
Following the air puff test, any momentary sensation of pressure or blinking subsides immediately. Your eye care professional will review the IOP readings with you. If your intraocular pressure falls within the typical range, no immediate follow-up is usually required, and your comprehensive eye exam will continue.
However, if the test indicates elevated eye pressure, your eye care professional will likely recommend additional evaluations. These may include a different type of tonometry, such as applanation tonometry, which provides a more precise measurement. Further assessments like visual field tests, optical coherence tomography (OCT) scans to examine the optic nerve, or a gonioscopy to inspect the eye’s drainage angle may also be suggested to thoroughly investigate the cause of the elevated pressure.