Tonometry plays a critical role in the detection and management of glaucoma. But what exactly is it? Tonometry refers to diagnostic tests that measure your intraocular pressure (IOP), also known as the pressure inside your eyes. Tonometry helps in identifying abnormal eye pressure which could lead to optic nerve damage and/or vision loss if left untreated.
To fully understand the importance of tonometry, let’s quickly breakdown intraocular pressure. IOP refers to the fluid pressure inside the eye, which is maintained by a balance between the production and drainage of aqueous humor, the clear fluid inside the eye. Eye doctors will evaluate the range of IOP to determine if it is normal or elevated. Elevated IOP is a major risk factor for glaucoma, as well as other eye diseases.
There are a few different tonometry methods, all of which are simple and painless. Let’s take a look:
Applanation tonometry is one of the most widely used and accurate methods for measuring IOP. This technique involves flattening a small area of the cornea to gauge the eye pressure. The device measures how much pressure it takes to make your eyes surface start to flatten.
Non-contact tonometry, also known as the "air puff" test, is a method that does not require contact with the eye. Devices utilizing this method push air at your cornea, and then measures split-second changes in the shape of your cornea as the air bounces off its surface.
Non-contact tonometry can be less accurate than applanation tonometry, especially in patients with certain corneal abnormalities.
Rebound tonometry is a relatively newer method that measures IOP by bouncing a small plastic probe off the cornea. The handheld device is easy to use, portable and user-friendly.
The importance of tonometry in the diagnosis and management of glaucoma cannot be overstated. Glaucoma is often asymptomatic in its early stages, and elevated IOP may be the only indicator of the disease. Regular IOP measurements help in the early detection of glaucoma, allowing for timely intervention and treatment. For those already diagnosed with glaucoma, ongoing monitoring of IOP is crucial. Tonometry allows eye care providers to assess the effectiveness of treatment, whether it involves medications, laser therapy, or surgery. Adjustments to the treatment plan can be made based on the IOP readings, ensuring better control of the disease.