Non-contact tonometer

A non-contact tonometer is described for measuring the intra-ocular pressure (IOP) of the eye. An ultrasonic power transducer directs an ultrasonic beam onto the eye and the force generated by the radiation pressure causes indentation or applanation which is detected by ultrasonic or optical means. An optical system provides an image of the eye with appropriate alignment beams injected through a beam splitter for positioning the device with respect to the eye. An additional ultrasonic beam may be used to measure the range to the eye. Another optical means is utilized to measure applanation or indentation; alternatively, an additional ultrasonic transducer and beam could be used. Operation of the device may be through continuous wave or pulsed excitation of the ultrasound. Feed-back control of the ultrasound power level is possible using an additional ultrasonic transducer for measuring the power levels to augment measurement accuracy.