An Unusual Case of Recurrent Hypokalemia Followed Electroretinographically

The effect of different ions on the electroretinogram (ERG) was studied by Beuchelt in 1921, but his method was rather slow to give satisfactory informations as to the selective effect on the retinal potentials. Later Therman (1938) found that application of 0.5% potassium chloride in isotonic glucose to the opened eye of the frog quickly removed the positive responses, leaving an isolated negative ERG. To quote from Granit (1947) the very first effect of potassium was that of removing the small oscillations superimposed on the ERG; the next effect was to increase the a — wave and diminish the b — wave.