The present invention provides an applanation tonometer comprising a light source and a measurement head for applying an applanation pressure to a cornea. Control means for controlling the pressure applied by the measurement head to the cornea are provided and include a cam. The tonometer further comprises a sensor for detecting the rotational position of the cam. The sensor is configured to produce an electrical output and a microcontroller is provided which is configured to convert the electrical output of the sensor into a digital output which corresponds to the pressure applied by the measurement head to the cornea. The sensor is a rotary potentiometer attached to the cam or a digital compass configured to detect the rotational position of the cam.
