What type of tonometry requires the application of a local anesthetic?

Applanation tonometry is a method that requires the application of a local anesthetic because it involves direct contact with the cornea. The procedure assesses intraocular pressure by flattening a small area of the cornea, which necessitates minimizing discomfort for the patient. The use of a local anesthetic helps to numb the cornea, ensuring that the patient feels little to no pain during the tonometry process, thus allowing for a more accurate and comfortable examination.

In contrast, non-contact tonometry employs a puff of air to measure intraocular pressure without any direct contact with the eye, making the use of anesthetic unnecessary. Similarly, pneumatic tonometry uses a small, handheld device that measures the pressure based on the cornea's response to applied air, which does not require local anesthesia either. Rebound tonometry uses a small probe that briefly touches the eye, but unlike applanation tonometry, it typically does not necessitate anesthetic because the interaction is very brief and generally not uncomfortable for the patient.