Electroretinographic studies were carried out in ten patients suffering from unilateral occlusion of the central retinal artery by using twin light flashes (interval of 500 msec), the intensity of which varied within a range of 5 log units. The pathologic conditions in the affected eyes caused a characteristic flattening of the intensity-response curves predominantly in the scotopic part of the curve. The shape changes of the intensity-response curves due to the relative refractory period following the first retinal responses are of a different nature. The procedure enables the quantitative analysis of the wide range of retinal intensity functions.