High frequency eye tremor: reliability of measurement.

Recent reports suggest that high frequency eye tremor or ocular microtremor (OMT) may be a useful indicator of brainstem function. The method of record analysis, and in particular the amount of record subjected to such analysis, has varied widely. We have recorded OMT from 10 normal subjects. Using these records we have performed 42 distinct replication reliability studies. We suggest seven parameters of OMT (including overall frequency of tremor) which may be of value in comparing abnormal with normal records. For each parameter we have determined the optimal duration of the record to analyse and the reliability of such analysis. Our results suggest that at least 5 s of OMT should be analysed to yield an acceptable estimate of all seven parameters.