Tonometry measures intraocular pressure IOP, a key risk factor for glaucoma. Several techniques exist, each with advantages and limitations.
Types of tonometry
Common methods include:
- Goldmann applanation tonometry, the gold standard in clinics
- Non-contact “air puff” tonometry often used in screening
- Handheld devices such as iCare rebound tonometers for children or bedside use
- Indentation methods like Schiotz tonometry in limited settings
Interpreting results
IOP values must be considered in context.
- Normal range is roughly 10-21 mmHg, but damage can occur outside this range
- Corneal thickness and biomechanics influence readings
- Serial measurements help detect fluctuation or progression
- Tonometry is always combined with optic nerve and field assessment for glaucoma diagnosis
