Which tonometry technique displaces a minimal amount of fluid?

The technique that displaces a minimal amount of fluid is the applanation tonometry method. Applanation tonometry measures the intraocular pressure by flattening a small area of the cornea. This technique, often represented by the Goldmann applanation tonometer, involves applying a blue light source to visualize the cornea as it is flattened by a known force. The amount of force required to achieve this flattening is directly related to the intraocular pressure.

In contrast, indentation tonometry involves pushing a probe against the eye, which can cause more significant displacement of the fluid inside the eye. The other methods, such as elevation tonometry, are not standard techniques recognized for measuring intraocular pressure in this context. Therefore, applanation's mechanism of gently displacing corneal fluid while exerting a controlled amount of pressure makes it the preferred method for accurate intraocular pressure assessments.