Detailed Tonometry (Intraocular Pressure Measurement)

Tonometry measures the intraocular pressure (IOP) inside the eye, which is a key factor in diagnosing and managing glaucoma, a disease that can cause irreversible vision loss if untreated. Regular IOP monitoring also helps evaluate the effects of medications, surgery, or other eye diseases affecting pressure regulation.

• No special dietary restrictions are needed.
• Remove contact lenses before the test.
• Tell your ophthalmologist if you have eye infections, recent eye surgery, or corneal conditions, as these may influence technique selection.
• If eye drops are prescribed before the exam (such as anesthetic or fluorescein dye), the technician will apply them in the clinic.

There are several types of tonometry:

• Applanation tonometry (Goldmann standard): A blue light and fluorescein dye are used with a slit lamp to measure corneal flattening under anesthesia drops.
• Non-contact (“air puff”) tonometry: A quick puff of air measures corneal response - no drops needed.
• Electronic or rebound tonometry: A handheld device touches the cornea lightly to measure resistance.

The test is brief, usually less than 5 minutes per eye, and generally painless.

• Temporary stinging or watery eyes from anesthetic drops.
• Rare risk of eye infection or corneal abrasion with contact methods.
• Air-puff methods may cause momentary discomfort but no lasting effects.

Normal IOP is typically 10–21 mmHg, but interpretation depends on corneal thickness and the patient’s risk profile. Elevated pressure may prompt additional tests such as optic nerve imaging, visual field testing, or pachymetry. Results guide treatment decisions, including medications, laser therapy, or surgery.