Recording of the fast oscillations in the human electro-oculogram.

The fast oscillations (FO) of the electro-oculogram were recorded in 102 eyes of 51 normal subjects. We evaluated the normal range and variability of FO parameters, i.e. Rf, which is the average ratio in percentage of the average amplitude in the dark period (AD) and the average amplitude in the light period (AL), and df, which is the average difference between AD and AL in microV. The standing potential was recorded continuously during six subsequent cycles, each consisting of a one minute period in the dark and one minute period in the light. The mean +/- standard error for Rf was 112.9 +/- 1.3% and 69.6 +/- 5.3 microV for df. There was no statistically significant difference between both genders or different age groups. Rf and df were calculated using a different number of dark-light cycles. In normal subjects both the Rf and df show no difference when only 4 dark-light cycles are used in calculating these values. Therefore there seems no additional advantage in performing as many as 6 cycles. Using 4 dark-light cycles reduces the duration of the examination (8 vs. 12 min) of the fast oscillations and in particular when examining both fast and slow oscillations successively it might be useful to reduce the time of the examination.