A rebound tonometer is improved by providing a tilt signal from a tilt sensor of the rebound tonometer to a signal processor of the rebound tonometer, and configuring the signal processor to apply a tilt correction factor to a basic IOP measurement value calculated by the signal processor to provide a final IOP measurement value, wherein the tilt correction factor depends on a tilt direction and a degree of tilt indicated by the tilt signal. The final reported IOP measurement value takes into account gravitational effects on the probe due to tilt. As a result, measurements made at relatively small tilt angles are now usable, thereby improving efficiency. A corresponding rebound tonometry measurement method, and a method of calibrating a rebound tonometer for tilt correction, are also disclosed.