K 155The interaction of alcohol with the human RPE compared to light
F. Singbartl, C. Hörmann, G. B. Arden ,T. A. Berninger
Introduction: Analysis of the effect of low-dose alcohol on human retinal Pigmentepithelium and investigation of the RPE voltage changes evoked by light and alcohol. For measuring the bioelectrical potential of the RPE the electrooculogramm (EOG) is used, which detects the changes in voltage at the basal membrane of the RPE. Light produces a corneo-fundal voltage change, which is used for diagnosis of several eye-diseases. Alcohol has been reported to have a similar effect, but was not investigated further so far.
Methods: 25 randomised test persons aged 18-60 years (divided in two groups; first:18-30 years, average 23.4 years, median 23; second: 31-60 years, average 46.3 years, median 42) were examined. All subjects had a normal ophthalmological status.
Results: After the oral administration of 80 ml of diluted alcohol (con-centration: 20%) an increase of about 150% is shown in the potential of the basal RPE. Although the peak in the EOG is very similar to the answer on light stimulation it is delayed by about 3 minutes, which likely depends on the alcohol absorption. The rise of the bioelectrical potential of the RPE reaches its peak after 9 minutes and than decreases steadily until it reaches a trough (65% normal) 20 minutes after the maximum. It needs about 3-4 oszillations more to come back to normal. This again is very similar compared to the conventional EOG.
Dicussion: The change in the RPE potential after stimulating it with alcohol is so similar compared to the effect of light stimulation, that they must have the same influence on the RPE. In fact alcohol and light must act via separate pathways onto a common terminal stretch inside the RPE cell. Consequently, in diseases associated with loss of photoreceptors, alcohol should continue to produce the voltage changes of the EOG unless either alcohol acts on photoreceptors or secondary changes have occurred in the RPE. Thus we have seen patients with retinal disease where the conventional light EOG was extinguished while the Alcohol-EOG was still presented. In patients with RP the EOG is reduced with both stimuli.
We thank Chibret, Germany, for the support of the study.
University Eye Hospital, Munich, Mathildentstr. 8 80336 Munich, Germany