Effect of alcohol and light on the retinal pigment epithelium of normal subjects and patients with retinal dystrophies.

BACKGROUND Light absorbed by photoreceptors causes oscillations in the voltage across the retinal pigment epithelium (RPE). This is the basis of the clinical test, electro-oculography (EOG). We have previously shown that alcohol causes a sequence of voltage changes which are so precisely the same as those caused by light that they must be produced by the same RPE machinery. There is good evidence that alcohol produces its effect by a direct action on the RPE. Consequently, in diseases associated with loss of photoreceptors, alcohol should continue to produce the voltage changes of the EOG unless secondary changes have occurred in the RPE. METHODS The alcohol response in patients with retinitis pigmentosa (RP) was investigated using EOG. RESULTS In no patient with RP was there any alcohol rise. CONCLUSION In patients with RP secondary abnormalities of function of the RPE must occur.