 Several macular diseases are thought to be caused only by a reduced function of the RPE cells. Therefore a method for the selective destruction of the RPE cells without causing adverse effects to choroid and neuroretina, especially to the photoreceptors, seems to be an appropriate treatment SRT. The selective effect on RPE cells, which absorb about 50 of the incident light due to their high melanosome content has been demonstrated using 5 μs argon laser pulses at 514nm with a repetition rate of 500 Hz. By irradiating the fundus with a train of μs laser pulses it was possible to achieve high peak temperatures around the melanosomes. This led to a destruction of the RPE, but only a low sublethal temperature increase in adjacent tissue structures. This selective destruction of the RPE cells sparing the photoreceptors without causing laser scotoma has been proven by histologic examinations at different times after treatment. The first clinical trial using a Nd:YLF laser system with a pulse duration of 1,7μs 100 pulses, 100 and 500 Hz also proved the concept of selective RPE destruction and demonstrated the clinical potential of this technique. However, one of the problems concerning selective RPE laser destruction is the inability to visualize the laser lesions. Therefore it is necessary to perform fluorescein angiography after treatment to confirm the laser success and to make sure that sufficient energy was used. Since dosimetry of such laser lesions is not known, test lesions with various energy and numbers of pulses in non-significant areas of the macula - usually at the lower vessel arcade - have to be applied to elucidate the energy levels required for treatment. If the RPE is damaged, or the tight junctions of the RPE barrier are broken, fluorescein from angiography can pool from the choriocapillaris into the subretinal space. Thus fluorescein angiography has been used to detect a break of the RPE barrier. However, fluorescein angiography is an invasive method and has as already described a potential risk for allergic reactions because of the intravenous injection of the fluorescein dye. 