Impression tonometry (also known as indentation tonometry) measures the depth of corneal indentation made by a small plunger carrying a known weight.
The higher the intraocular pressure, the harder it is to push against and indent the cornea.
For very high levels of IOP, extra weights can be added to make the plunger push harder.
The movement of the plunger is measured using a calibrated scale.
The Schiøtz tonometer is the most common device to use this principle.
Impression tonometry (also known as indentation tonometry) measures the depth of corneal indentation made by a small plunger carrying a known weight. The higher the intraocular pressure, the harder it is to push against and indent the cornea. For very high levels of IOP, extra weights can be added to make the plunger push harder. The movement of the plunger is measured using a calibrated scale. The Schiøtz tonometer is the most common device to use this principle.
Ocular tonometry