VIDEO CONTROLLED M-MODE BIOMETRY

To increase the accuracy of intraocular lens power calculation, an int erface between an ultrasonic A-scanning device and a personal computer ,vas created, allowing for an on-line interpretation of the ultrasonog ram in an M-mode fashion. On the same computer display, a video record ing of the movements of the transducer probe relative to the eye was i nserted to obtain simultaneous information on the external alignment o f the transducer probe. The precision of the experimental set-up in th e measurement of intraocular distances was compared with conventional A-scanning procedures run in automatic mode. The video controlled M-mo de biometry was found easy to operate and to result in reproducible ax ial length determination: The median value of the standard deviation w as found to be below 0.04 mm as compared to a value of about 0.10 mm w ith conventional equipment. We concluded that video controlled M-mode biometry has great potential in the endeavour to increase the accuracy of intraocular lens calculation.