 The beneficial effect in laser treatment of diabetic macular edema is thought to be associated with the restoration of a new barrier of retinal pigment epithelium cells. A similar effect is postulated in the treatment of drusen, central serous retinopathy and macular edema after vein occlusion. If these latter theories are true, the destruction of the photoreceptors causing visual field defects would be only an unwanted and unnecessary side effect. Thus, SRT is able to avoid these unintentional side effects and to achieve the benefit by just treating the RPE. 