PURPOSE. Alcohol produces changes in the electro-oculogram (EOG) similar to those caused by light, but indirect evidence indicates that alcohol directly affects the retinal pigment epithelium (RPE). An investigation of the alcohol-induced increase (termed the alcohol rise in this study) in patients with disease of the photoreceptors was therefore of interest. METHODS. Standard EOGs were recorded after oral administration of alcohol in a group of patients with retinitis pigmentosa (RP). RESULTS. The average response of 17 patients to alcohol was a slow decrease of potential, which contrasts with the normal alcohol rise. In patients with considerable residual peripheral field, alcohol produced a small increase of voltage, followed by a prolonged decrease. The slower decrease in the EOG voltage was evident in patients with small fields and could be seen even in those who had lost all visual function. Light caused small increments of EOG voltage (termed light rises), again related to the field size. CONCLUSIONS. It is probable that the intracellular signaling system that causes the alcohol and light rises is lost in RP. (Invest Ophthalmol Vis Sci. 2000;41:2730 -2734 T he light-induced increase (termed light rise in this study) of the EOG is produced by the liberation of an unknown substance from the retina, which has been shown to affect second-messenger systems in the apical membrane of the RPE. 1,2 Results in a companion study 3 demonstrated that small oral doses of alcohol produce an effect on the EOG that is indistinguishable from that evoked by light, except for a delay due to the time required to absorb alcohol from the gut. The interactions between alcohol and light were investigated, and the inference from the results was that alcohol (similar to other agents) is able to alter the basolateral conductance of the RPE by a pathway that probably involves second messengers, but not the retina. 5 Because many of the photoreceptors in such retinas are nonfunctional, the failure to release a light rise substance is not surprising, and the EOG light rise is known to be greatly reduced. METHODS Seventeen patients were recruited by contacting the British Retinitis Pigmentosa Society, by letter and on its Web sites, and asking for volunteers, who were then given a written explanation of the proposed test, so they could provide informed consent. All the patients were under the care of specialist eye departments. One patient was excluded because he had bilateral cataract extraction with ocular implants. We did not accept patients under 18 years of age or those with other systemic conditions. The age range was between 22 and 74 years. The work was performed in accordance with the Declaration of Helsinki. Standard EOG recordings of 30°horizontal eye movements were made as described in a previous article, 3 except in the case of patients with very reduced vision, when the patients made extreme eye movements that were measured as 90°. The (ethyl) alcohol was administered after subjects fasted for more than 12 hours (0.3 g/kg, 20% wt/vol in water, drunk in 15 seconds). Other clinical tests (fields, electroretinograms [ERGs]) were performed in a standard fashion in patients with the best preserved vision to confirm clinical diagnoses. ERGs were elicited by equipment (a LED-powered miniganzfeld stimulus) similar to that already described
