There are few pieces of diagnostic equipment in eye care that have stood the test of time as admirably as the Goldmann Applanation Tonometer (GAT). Through the decades, a variety of IOP measurement modalities have been developed but GAT remains widely regarded as the most accurate and repeatable. It is still the mainstay of IOP measurement within hospital glaucoma clinics.

The aim of this article is to offer an overview of when we should use this technique, how to carry it out, and provide guidance on how to minimise inaccuracies.