Circadian rhythms and variability of the clinical electro-oculogram.

Clinical electro-oculograms (EOGs) were recorded from six normal subjects over 24 hr time periods for a total number of 70 EOG'S. Results indicate an inverse relationship exists between the light/dark (L/D) ratio and the dark-trough potential. No relationship was found between the light-peak potential and the L/D ratio. Both the dark-trough potential and the L/D ratio showed a circadian periodicity over working daylight hours and rather aberrant behavior in late evening and early morning hours. Circadian contributions to the L/D ratio are estimated to be between 20% and 50% of the total variability in the normal individuals studied. We suggest the optimal time for single measurements of EOG pathology should be around midday.