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Applanation tonometry is a test that measures eye pressure by gently flattening a small area of the cornea. It is considered one of the most accurate ways to check for elevated pressure linked to glaucoma. The test uses a device that applies controlled force to the eye's surface. Numbing drops are used so the patient remains comfortable throughout the process.
read more about applanation tonometry ...Measuring eye pressure helps identify risks that may affect the optic nerve. Elevated pressure does not always cause symptoms, so routine testing is important for early detection. Many providers rely on applanation tonometry during regular exams or glaucoma evaluations. It helps guide treatment decisions and long-term monitoring.
A drop of anesthetic is placed on the eye, followed by a small amount of dye that helps the device read pressure. The tonometer then makes gentle contact with the cornea to measure how much force is needed to flatten it. The reading reflects the amount of pressure inside the eye. The test takes only a few seconds per eye.
The air puff test estimates pressure without touching the eye, while applanation tonometry provides a more precise measurement. The applanation method is often preferred for diagnosing and monitoring glaucoma. It uses direct contact instead of air to determine pressure. Many clinics use both tests depending on the situation.
It is recommended during routine eye exams for adults, especially those at risk for glaucoma. Patients with a family history of the condition often receive it more frequently. People with elevated pressure or optic nerve changes rely on repeated measurements for monitoring. The test is a standard part of glaucoma care.
It usually doesn't hurt because numbing drops are used first. Most people only feel light pressure or a brief touch. The test takes a few seconds per eye, so the contact is quick. If you're anxious, focusing on breathing and keeping your head steady can help.
It measures pressure by direct, controlled flattening of the cornea, which gives a precise reading. The air-puff method estimates pressure and can be less consistent, especially in borderline cases. Many clinics use air-puff for screening and applanation for confirmation. For glaucoma monitoring, accuracy matters because small changes can affect treatment decisions.
Yes, thickness and corneal properties can influence pressure measurements. A thicker cornea can make pressure seem higher than it truly is, while a thinner cornea can make it seem lower. That's why some exams include pachymetry to measure corneal thickness. Providers interpret pressure numbers with corneal data in mind.
It's commonly included in routine adult exams, especially after age 40 or for people with risk factors. Patients with glaucoma or elevated pressure often need it more frequently to track trends. The schedule depends on optic nerve findings, pressure history, and treatment changes. Consistent testing helps spot shifts before they cause noticeable symptoms.
1. Goldmann H, Schmidt T. Foundational publications describing applanation tonometry principles (mid-20th century ophthalmology literature).
2. American Academy of Ophthalmology (AAO). Basic and Clinical Science Course (BCSC): Section 10 (Glaucoma)—tonometry and interpretation.
3. American Academy of Ophthalmology (AAO). Preferred Practice Pattern: Primary Open-Angle Glaucoma (IOP measurement and monitoring guidance).
4. EyeWiki (AAO). “Goldmann Applanation Tonometry” / “Tonometry” topic pages.
5. Wills Eye Manual. Glaucoma workup section (IOP testing and follow-up).
6. Ocular Hypertension Treatment Study (OHTS). Publications discussing risk assessment and factors tied to IOP interpretation (including corneal thickness considerations).
7. International Organization for Standardization (ISO). ISO standards for tonometers (instrument requirements and calibration topics).