An A-scan ultrasound system is described which allows visualization along the ultrasonic path to assure alignment with the patient's visual axis. A special "sound collimator" produces a 2-mm beam from a 10-megacycle transducer which is aimed through a water column and eye cup mounted in such a way as not to cause contact deformation of the globe. Measurements are made from gated portions of the signal with an electronic interval counter and a photographic record is taken.