A microprocessor-based instrument for nystagmus analysis

This paper describes a microprocessor-based instrument for on-line recording and analysis of ocular nystagmus. A novel acceleration sensitive saccade detector is used to differentiate between slow and fast phases of nystagmus. Once saccades are located, they are removed and an estimate of cumulative slow phase position is obtained. Also available as outputs are slow phase velocity, saccadic frequency, and maxima and times of occurrence for each of these parameters. The advantages of such an insmunent include low cost coupled with a high level of sophistication. These factors would allow the instrument to be used in a physician's office by relatively naive personnel Software is written in STOIC, a new general purpose interactive language for microprocessors. An Intel 8080 microprocessor, 16K of memory, A/D and D/A converters, interrupting clock, and CRT terminal are used in the present configuration. The system provides semi-automatic calibration of eye movement monitoring and detection of excessive drift and noise artifacts. Flowcharts for the processing algorithm and examples of output are presented.