Principles of contact lens tonometry.

We constructed a contact lens with an integrated pressure-sensing device. It is housed in a container with three force-sensing elements, each 120° apart, enabling measurement of the appositional force, i.e., the force with which the instrument is held against the eye. In part 1 of the study, the lens' precision was tested against a manometric transducer in five eye bank eyes. The second part examined pressure as a factor dependent on the appositional force, and the third part of the study investigated the correct procedure for measuring baseline eye pressure, p0.